Programming Language Eulisp
Version
Programming Language EuLisp version
Contents Page
Foreword
Intro duction
Language Structure
Scop e
Conformance De nitions
Error De nitions
Compliance
Conventions
Layout and Typ ography
Meta Language
Naming
De nitions
Syntax
Whitespace and Comments
Ob jects
Mo dules
Directives
Exp ort Directive
Imp ort Directive
Exp ose Directive
Syntax Directive
De nitions and Expressions
Mo dule Pro cessing
Mo dule De nition
Ob jects
System De ned Classes
Single Inheritance
De ning Classes
De ning Generic Functions and Metho ds
Sp ecializin g Metho ds
Metho d Lo okup and Generic Dispatch
Creating and Initializi ng Ob jects
Accessing Slots
Concurrency
Threads
Lo cks
Conditions
Condition Classes
Condition Handling ii
Programming Language EuLisp version
Expressions De nitions and Control Forms
Simple Expressions
Functions creation de nition and application
Destructive Op erations
Conditional Expressions
Variable Binding and Sequences
Events
Quasiquotation Expressions
Summary of Level Expressions and De nitions
Syntax of Level de ning forms
Syntax of Level expressions
Syntax of Level macros
Annexes
ALevel Mo dule Library
A Characters
A Collections
A Comparison
A Conversion
A Copying
A Double Precision Floats
A Elementary Functions
A Floating Point Numbers
A Fixed Precision Integers
A Formatted IO
A Integers
A Lists
A Numbers
A Streams
A Strings
A Symbols
A Tables
A Vectors
A Syntax of Level ob jects
B Programming Language EuLisp Level
B Classes and Ob jects
B Generic Functions
B Metho ds
B Ob ject Introsp ection
B Class Introsp ection
B Slot Introsp ection
B Generic Function Introsp ection
B Metho d Introsp ection
B Class Initializa tion
B Slot Description Initializa tion
B Generic Function Initializ ation
B Metho d Initializati on
B Inheritance Proto col
B Slot Access Proto col
B Metho d Lo okup and Generic Dispatch
B LowLevel Allo cation Primitives
B Dynamic Binding
B Exit Extensions
B Summary of Level Expressions and De nitions
B Syntax of Level de ning forms
B Syntax of Level expressions
B Syntax of Level macros
Indexes
Class Index
Condition Index
ConstantIndex
Function Index
Macro Index
Generic Function Index
Metho d Index iii
Programming Language EuLisp version
General Index
Figures
Example of mo dule directives
Example mo dule using expose
Level initial class hierarchy
Level initial condition class hierarchy
Illustration of handler actions
Example using let cc
Interaction of unwind protect with non lo cal exits
A Level numb er class hierarchy
B Level class hierarchy
B Initializati on Call Structure
Tables
Mo dules comprising eulisp level
Minimal character set
Syntax of ob jects for reading and writing
Mo dule syntax
defstruct syntax
defgeneric rewrite rules
A Character Syntax
A Summary of comparison functions
A Floating Point Syntax
A Integer Syntax
A Pair and List Syntax
A Examples of string literals
A String Syntax
A Identi er Symb ol Syntax
A Vector Syntax iv
COMMITTEE DRAFT Programming Language EuLisp version
Programming Language EuLisp version
In the b eginning the work of the EULISP group was sup
p orted by the institutions or companies where the partici
pants worked but in DG XI I I Information technol
ogy directorate of the Commission of the Europ ean Com
munities agreed to supp ort the continuation of the work
ing group by funding meetings and providing places to
meet It can honestly b e said that without this supp ort
EULISP would not have reached its presentstate In ad
dition the EULISP group is grateful for the supp ort of
British Council in France Alliance programme British
Council in Spain Acciones Integradas programme British
Council in Germany Academic Research Collab oration pro
gramme British Standards Institute Deutscher Akademis
cher Austauschdienst DAAD Departament de Llenguat
ges i Sistemes Inform atics LSI Universitat Polit ecnica de
Catalunya Fraunhofer Gesellschaft Institut fur Software
Foreword
und Systemtechnik Gesellschaft fur Mathematik und Daten
verarb eitung GMD ILOG S A Insiders GmbH Institut
The EULISP group rst met in Septemb er at IRCAM
National de Recherche en Informatique et en Automatique
in Paris to discuss the idea of a new dialect of Lisp which
INRIA Institut de Recherche et de Co ordination Acous
should b e less constrained by the past than Common Lisp
tique Musique IRCAM Rank XeroxFrance Science and
and less minimalis t than Scheme Subsequent meetings for
Engineering Research Council UK Siemens AG University
mulated the view of EULISP that was presented at the
of Bath UniversityofTechnology Delft University of Edin
ACM Conference on Lisp and Functional Programming held
burgh Universit at Erlangen and Universit eParis VI LITP
at MIT Cambridge Massachusetts and at the Euro
p ean Conference on Arti cial Intelligence ECAI held
The following p eople in alphab etical order have con
in Brighton Sussex Since then progress has not b een
tributed in various ways to the evolution of the language
steady but happ ening as various p eople had su cient time
ejar Russell Bradford Harry Giusepp e Attardi Javier B
and energy to develop part of the language Consequently
Bretthauer Peter Broadb ery Christopher Burdorf J er ome
although the vision of the language has in the most part
Chailloux Thomas Christaller Je Dalton Klaus D a ler
b een shared over this p erio d only certain parts were turned
Harley Davis David DeRoure John Fitch Richard Gabriel
into physical descriptions and implementations For a nine
Brigitte Glas Nicolas Graub e Dieter Kolb Jurgen Kopp
month p erio d starting in January through the supp ort
Antonio Moreno Eugen Neidl Pierre Parquier Keith Play
of INRIA it b ecame p ossible to start writing the EULISP
ford Willem van der Po el Christian Queinnec Enric Sesa
de nition Since then a airs have returned to their previ
Herb ert Stoyan and Richard Tobin
ous state but with the evolution of the implementation s of
EULISP and the background of the foundations laid by the
The editors of the EULISP de nition wish particularly to ac
INRIA supp orted work there is convergence to a consistent
knowledge the work of Harley Davis on the rst versions of
and practical de nition
the description of the ob ject system The second version was
largely the work of Harry Bretthauer with the assistance of
The acknowledgments for this de nition fall into three cate
J urgen Kopp Harley Davis and Keith Playford
gories intellectual p ersonal and nancial
Julian Padget jap maths bath ac uk
The ancestors of EULISP in alphab etical order are Common
Scho ol of Mathematical Sciences
Lisp I nterLISP LE LISP LISP VM Scheme and
University of Bath
T Thus the authors of this rep ort are pleased to
Bath Avon BA AY UK
acknowledge b oth the authors of the manuals and de nitions
of the ab ove languages and the many who have dissected and
extended those languages in individ ual pap ers The various
Greg Nuyens nuyens ilog com
pap ers on Standard ML and the draft rep ort on Haskell
ILOG SA
have also provided much useful input
Avenue Galli eni
Gentilly CEDEX FRANCE
The writing of this rep ort has at various stages b een sup
p orted by Bull S A Gesellschaft fur Mathematik und Daten
verarb eitung GMD Sankt Augustin Ecole Polytechniqu e
editors
LIX ILOG S A Institut National de Recherche en Infor
matique et en Automatique INRIA University of Bath
and Universit eParis VI LITP The authors gratefully ac
knowledge this supp ort Many p eople from Europ ean Com
munitycountries have attended and contributed to EULISP
meetings since they started and the authors would liketo
thank all those who have help ed in the development of the
language
Programming Language EuLisp version
necessary But this is not the place for a detailed language
comparison That can b e drawn from the rest of this text
EULISP breaks with LISP tradition in describing all its typ es
in fact classes in terms of an ob ject system This is called
The EULISP Ob ject System or TELOS TELOS incorp orates
elements of the Common Lisp Ob ject System CLOS Ob
jVLisp Oaklisp MicroCeyx and MCS
Language Structure
The EULISP de nition comprises the following items
Intro duction
Level comprises all the level functions macros
EULISP is a dialect of Lisp and as suchowes much to the
and sp ecial forms which is this text minus Annex B The
great b o dy of work that has b een done on language design in
ob ject system can b e extended by user de ned structure
the name of Lisp over the last thirtyyears The distinguish
classes and generic functions
ing features of EULISP are i the integration of the classical
Lisp typ e system and the ob ject system into a single class
Level extends level with the functions macros
hierarchy ii the complementary abstraction facilities pro
and sp ecial forms de ned in Annex B The ob ject system
vided by the class and the mo dule mechanism iii supp ort
can b e extended by user de ned classes and metaclasses
for concurrent execution
The implementation of level is not necessarily written or
writable as a conforming level program
Here is a brief summary of the main features of the language
A level function is a generic function de ned in this text
Classes are rst class ob jects The class structure
to b e part of a conforming pro cessor for level A function
integrates the primitive classes describing fundamental
de ned in terms of level op erations is an example of a level
datatyp es the prede ned classes and user de ned classes
application
Mo dules together with classes are the building blo cks
Much of the functionalityofEULISP is de ned in terms of
of b oth the EULISP language and of applicatio ns written
mo dules These mo dules mightbeavailable and used at
in EULISP The mo dule system exists to limit access to
anylevel but certain mo dules are required at a given level
ob jects by name That is mo dules allow for hidden de
Whenever a mo dule dep ends on the op erations available at
nitions Each mo dule de nes a fresh empty lexical envi
agiven level that dep endency will b e sp eci ed
ronment
EULISP level is provided by the mo dule eulisp level
Multiple control threads can b e created in EULISP
This mo dule imp orts and re exp orts the mo dules sp eci ed
and the concurrency mo del has b een designed to allow
in Table
consistency across a wide range of architectures Access
to shared data can b e controlled via lo cks semaphores
This de nition is organized in three parts
Event based programming is supp orted through a generic
waiting function
Sections describ es the core of level of EULISP
covering mo dules simple classes ob jects and generic func Both functions and continuations are rst class in
ISP but the latter are not as general as in Scheme EUL
tions threads conditions control forms and events These
b ecause they can only b e used in the dynamic extentof LISP that char sections contain the information ab out EU
their creation That implies they can only b e used once
acterizes the language
A condition mechanism which is fully integrated with
Annex A describ es the additional classes required at
b oth classes and threads allows for the de nition of
level and the op erations de ned on instances of those
generic handlers and which supp orts b oth propagation of
classes The annex is organized by class in alphab etical
conditions and continuable handling
order These sections contain information ab out the pre
de ned classes in EULISP that are necessary to make the
Dynamically scop ed bindings can b e created in
language usable but is not central to an appreciation of
EULISP but their use is restricted as in Scheme EULISP
the language
enforces a strong distinction b etween lexical bindings and
dynamic bindings by requiring the manipulation of the
Annex B describ es the re ective asp ects of the ob ject
latter via sp ecial forms
system and how to program the metaob ject proto col and
some additional control forms
EULISP do es not claim any particular Lisp dialect as its
closest relative although parts of it were in uenced by fea
tures found in Common Lisp InterLISP LE LISP LISP VM Prior to these sections de ne the scop e of the text and
Scheme and T EULISP b oth intro duces new ideas and takes error de nitions and typ ographical and layout conventions
from these Lisps It also extends or simpli es their ideas as used in this text
Programming Language EuLisp version
Table Modules comprising eulisp level
Conformance De nitions
Mo dule Section s
The following terms are general in that they could b e applied
character A
to the de nition of any programming language They are
collection A
derived from ISO IEC TR
compare A
condition
convert A
con guration Host and target computers anyop
copy A
erating systems s and software run time system used to
double float A
op erate a language processor
elementary functions A
event
fixed precision integer A
conformity clause Statement that is not part of
formatted io A
the language de nition but that sp eci es requirements for
function
compliance with the language standard
lock
null A
conforming program Program which is written in
number A
the language de ned by the language standard and which
object
ob eys all the conformity clauses for programs in the language
pair A
standard
stream A
string A
symbol A
conforming pro cessor Processor which pro cesses
syntax
conforming programs and program units and which ob eys all
table A
the conformity clauses for processors in the language stan
dard
vector A
incorrect error Incorrect program construct or
Scop e
functioning of a program as de ned by the language stan
dard
This text sp eci es the syntax and semantics of the computer
programming language EULISP by de ning the requirements
for a conforming EULISP pro cessor and a conforming EULISP
extension Facilityintheprocessor that is not sp ec
program the textual representation of data and algorithms
i ed in the language standard but that do es not cause any
ambiguityorcontradiction when added to the language stan
This text do es not sp ecify
dard
a The size or complexityofaEULISP program that will
exceed the capacityofany sp eci c con guration or pro
implementation de ned Sp eci c to the proces
cessor nor the actions to b e taken when those limits are
sor but required by the language standard to b e de ned
exceeded
and do cumented by the implementer
b The minimal requirements of a con guration that is
capable of supp orting an implementation of a EULISP pro
pro cessor Compiler translator or interpreter work
cessor
ingincombination with a con guration
c The metho d of preparation of a EULISP program for
execution or the metho d of activation of this EULISP pro
Error De nitions
gram once prepared
Errors in the language describ ed in this de nition fall into
d The metho d of rep orting errors warnings or excep
one of the following three classes
tions to the clientofaEULISP pro cessor
e The typ ographical representation of a EULISP pro
dynamic error An error which is detected during
gram for human reading
the execution of a EULISP program or which is a violation of
the de ned dynamic b ehaviour of EULISP Dynamic errors
f The means to map mo dule names to the ling system
havetwo classi cations
or other ob ject storage system attached to the pro cessor
a Where a conforming processor is required to detect
To clarify certain instances of the use of English in this text
the erroneous situation or b ehaviour and rep ort it This is
the following de nitions are provided
signi ed by the phrase an error is signal led The condition
class to b e signalled is sp eci ed Signallin g an error con
must averbal form used to intro duce a required prop
sists of identifying the condition class related to the error
erty All conforming pro cessors must satisfy the prop erty
and allo cating an instance of it This instance is initial
ized with information dep endent on the condition class A should Averbal form used to intro duce a strongly rec
conforming EULISP program can rely on the fact that this ommended prop erty Implementors of pro cessors are urged
condition will b e signalled but not required to satisfy the prop erty
Programming Language EuLisp version
mented by this processor due to non supp ort of a partic b Where a conforming processor mightormight not de
ular facility where such non supp ort is p ermitted by the tect and rep ort up on the error This is signi ed by the
standard phrase is an error A pro cessor should provide a mo de
where such errors are detected and rep orted where p ossi
ble
c A list of all the features of the language implemented
bythis processor whichareextensions to the standard
language
environmental error An error which is detected
by the con guration supp orting the EULISP pro cessor The
d A statement of conformity giving the complete ref
pro cessor must signal the corresp onding dynamic error which
erence of the language standard with which conformity
is identi ed and handled as describ ed ab ove
is claimed and if appropriate the level of the language
supp orted by this pro cessor
static error An error which is detected during the
preparation of a EULISP program for execution suchasa
violation of the syntax or static semantics of EULISP by the
Conventions
program under preparation
This section de nes the conventions employed in this text
NOTE The violation of the syntactic or static semantic re
how de nitions will b e laid out the typ eface to b e used the
quirements is not an error but an error might b e signalled by the
meta language used in descriptions and the naming conven program p erforming the analysis of the EULISP program
tions A later section contains de nitions of the terms
used in this text All errors sp eci ed in this de nition are dynamic unless ex
plicitly stated otherwise
Layout and Typ ography
Compliance
Both la yout and fonts are used to help in the description of
EULISP A language element is de ned as an entry with its
An EULISP pro cessor can conform at either of the two levels
name as the heading of a clause coupled with its classi
de ned under Language Structure in the Intro duction Thus
cation Examples of several kinds of entry are now given
alevel conforming pro cessor must supp ort all the basic
Some subsections of entries are optional and are only given
expressions classes and class op erations de ned at level
where it is felt necessary
A level conforming pro cessor must supp ort all the basic
expressions classes class op erations and mo dules de ned at
level and at level
a special form special form
The following two statements govern the conformance of a
pro cessor at a given level
Syntax
a A conforming processor must correctly pro cess all pro
a special form form form
n
grams conforming b oth to the standard at the sp eci ed
level and the implementation de ned features of the pro
cessor
Arguments
b A conforming processor should o er a facility to re
p ort the use of an extension which is statically deter
form description of structure and r ole of form
minable solely from insp ection of a program without ex
ecution It is also considered desirable that a facilityto
rep ort the use of an extension which is only determinable
form description of structure and r ole of form
dynamically b e o ered n n
A level conforming program is one which observes the syn
tax and semantics de ned for level A level conforming
Result
program might not conform at level A strictly conforming
A description of the result
level program is one that also conforms at level A level
conforming program observes the syntax and semantics
de ned for level
Remarks
In addition a conforming program at any level must not use
Any additional information de ning the b ehaviour of
any extensions implemented by a language processor but it
a special form
can rely on implementation de ned features
The do cumentation of a conforming processor must include
Examples
Some examples of use of the sp ecial form and the b ehaviour
a A list of all the implementation de ned de nitions or
that should result
values
b A list of all the features of the language standard
which are dep endent on the processor and not imple See also Cross references to related entries
Programming Language EuLisp version
Sp ecialized Arguments
a function function
argument a class a means that argument a of the
metho d must b e an instance of class a Of course this
argumentmust b e one whichwas de ned in a generic
Arguments
as b eing op en to sp ecializa tion and class a mustbea
sub class of the class
argument a information ab out the class or classes of
argument a
argument n means that i argument n is an instance of
object i e it is unconstrained ii a generic do es not
argument n information ab out the class or classes of
sp ecialize on argument n iii no metho d on a generic
the optional argument argument n
can sp ecialize on argument n
Result
Result
A description of the result and p ossibly its class
A description of the result and p ossibly its class
Remarks
Remarks
Any additional information ab out the actions of a function
Any additional information ab out the actions of this metho d
attached to a generic
Examples
Some examples of calling the function with certain argu
See also Cross references to related entries
ments and the result that should b e returned
a condition a condition superclass
See also Cross references to related entries
Initializatio n Options
a generic generic function
initarg a value a means that an instance of
a condition has a slot called initarg a which should
Generic Arguments
b e initiali zed to value a where value a is often the name
of a class indicating that value a should b e an instance of
argument a class a means that argument a of
that class and a description of the information that value
a generic must b e an instance of class a and that
a is supp osed to provide ab out the exceptional situation
argument a is one of the arguments on which a generic
that has arisen
sp ecializes Furthermore each metho d de ned on
a generic may sp ecialize only on a sub class of class a
for argument a
initarg n value n As for initarg a
Remarks argument n means that i argument n is an instance of
object i e it is unconstrained ii a generic do es not
Any additional information ab out the circumstances in
sp ecialize on argument n iii no metho d on a generic
which the condition will b e signalled
can sp ecialize on argument n
class name class
Result
A description of the result and p ossibly its class
Initializatio n Options
Remarks
initarg a value a means that class name has an
initarg whose name is initarg a and the description will
Any additional information ab out the actions of a generic
usually say of what class or classes value a should b e an
This will probably b e in general terms since the actual b e
instance This initarg is required
haviour will b e determined by the metho ds
See also Cross references to related entries
initarg n value n The enclosing square brackets de
note that this initarg is optional Otherwise the interpre
tation of the de nition is as for initarg a
a generic method
Remarks
A metho d on a generic with the following sp ecialized ar
guments A description of the r ole of class name
Programming Language EuLisp version
Meta Language all condition classes The exception is class itself whichis
the default metaclass The pre x should describ e the general
domain of the classes in question but not necessarily any
The terms used in the following descriptions are de ned in
particular class in the set
Annex
A standard function denotes an immutable top lexical bind
ing of the de ned name All the de nitions in this text are
generic pre x The generic version of the
bindings in some mo dule except for the sp ecial form op era
function named by the stem
tors whichhave no de nition anywhere All bindings and
all the sp ecial form op erators can b e renamed
hyphenation Function and class names made up
NOTE A description making mention of an x where x is
of more than one word are hyphenated for example
the name a class usually means an instance of x
compute specialized slot description class
Frequently a class descriptive name will b e used in the ar
gument list of a function description to indicate a restric
tion on the domain to which that argument b elongs In the
p su x A predicate function is named bya p
case of a function it is an error to call it with a value out
su x if the function or class name after removing the enclos
side the sp eci ed domain A generic function can b e de ned
ing and is not hyphenated for instance consp andis
with a particular domain and or range In this case any
named bya p su x if it is for instance double float p
new metho ds must resp ect the domain and or range of the
generic function to which they are to b e attached The use of
a class descriptive name in the context of a generic function
de nition de nes the intention of the de nition and is not
De nitions
necessarily a p oliced restriction
This set of de nitions which are b e used throughout this
If it is required to indicate rep etition the notation
de nition is self consistentbutmight not agree with notions
expression and expression will b e used for zero or more
accepted in other language de nitions The terms are de ned
and one or more o ccurrences resp ectively The arguments in
in alphab etical rather than dep endency order and where a
some function descriptions are enclosed in square brackets
de nition uses a term de ned elsewhere in this section it
graphic representation and This indicates that the
is written in italics Some of the terms de ned here are
argument is optional The accompanying text will explain
redundant Names in courier font refer to entities de ned
what default values are used
in the language
The result class of an op eration except in one case refers to
a primitive or a de ned class describ ed in this de nition The
boolean A b o olean value is either false whichis
exception is for predicates Predicates are de ned to return
represented by the empty list written and is also the
either the empty list written representing the b o olean
or true whichisrepresented byany other value value of nil
value false or anyvalue other than representing true
than
Although the class containing exactly this set of values is not
de ned in the language notation is abused for convenience
and boolean is de ned for the purp oses of this rep ort to
class A class is an object which describ es the struc
mean that set of values If the true value is a useful value
ture and b ehaviour of a set of objects which are its instances
it is sp eci ed precisely in the description of the function
A class ob ject contains inheritance information and a set of
slot descriptions which de ne the structure of its instances
A class object is an instance of a metaclass All classes
Naming
in EULISP are subclasses of object and all instances of
class are classes
Naming conventions are applied in the descriptions of prim
itive and de ned classes as well as in the choice of other
function names Here is a list of the conventions and some
de ning form Any form or any macro expres
examples of their use
sion expanding into a form whose op erator is one
of defclass defcondition defconstant defgeneric
deflocal defmacro defstruct defun or defvar
name wrapping By convention classes have
names which b egin with and end with
direct instance A direct instance of a class class
is any object whose most sp eci c class is class
binary pre x The two argumentversion of a
n ary argument function There is not always a corresp on
dence b etween the ro ot and the name of the n ary function
direct sub class A class is a direct subclass of
for example binary plus is the two argument generic func
class if class is a subclass of class class is not identical
tion corresp onding to the n ary argument function
to class and there is no other class whichisasuperclass
of class and a subclass of class
class su x The name of a metaclass of a set
of related classes For example function class whichis
the class of simple function generic function and direct sup erclass A direct superclass of a class
any of their sub classes and condition class is the class of class is any class for which class is a direct subclass
Programming Language EuLisp version
inner lexical Inner lexical bindings are created by dynamic environment The inner and top dy
lambda and let cc referenced by variables and mo di ed by namic environment taken together are referred to as the
setq Inner lexical bindings extend and can shadow the dynamic environment
lexically enclosing lexical environment Note that let cc
creates an immutable binding
function A function is either a continuation a sim
ple function or a generic function
instance Every object is the instance of some
class An instance thus describ es an object in relation to
its class An instance takes on the structure and b ehaviour
generic function Generic functions are functions
describ ed by its class An instance can b e either direct or
for which the method executed dep ends on the class of its
indirect
arguments A generic function is de ned in terms of methods
which describ e the action of the generic function for a sp eci c
set of argument classes called the metho d s domain
instantiation graph A directed graph whose
no des are objects and whose edges are de ned bythein
stance relations b etween the objects This graph has only
indirect instance An indirect instance of a class
one cycle an edge from class to itself The instantation
class is any object whose class is an indirect subclass of
graph is a tree and class is the ro ot
class
lexical environment The inner and top lexical
indirect sub class A class is an indirect sub class
environment of a mo dule are together referred to as the lex
of class if class is a subclass of class class is not identical
ical environment except when it is necessary to distinguish
to class and there is at least one other class whichisa
between them
erclass of class and a subclass of class sup
metaclass A metaclass is a class object whose in
inheritance graph A directed lab elled acyclic
stances are themselves classes All metaclasses in EULISP
graph whose no des are classes and whose edges are de ned by
are instanc es of class whichisaninstance of itself All
the direct subclass relations b etween the no des This graph
metaclasses are also subclasses of class class is a
has a distinguish ed ro ot the class object whichisasu
metaclass
perclass of every class
metho d A metho d describ es the action of a
inherited slot description A slot description is
generic function for a particular list of argument classes
inherited for a class if the slot description is de ned for an
called the metho d s domain Amethod is thus said to add to
other class which is a direct or indirect superclass of class
the b ehaviour of eachoftheclasses in its domain Metho ds
are not functions but objects whichcontain among other in
formation a function representing the metho d s b ehaviour
initarg A symbol used as a keywordinaninitlist to
mark the value of some slot or additional information Used
metho d sp eci city A domain domain is more
in conjunction with make and the other object initializa tion
sp eci c than another domain if the rst class in domain
functions to initiali ze the ob ject An initarg may b e declared
is a subclass of the rst class in domain or if they are the
for a slot in a class de nition form using the initarg slot
same the rest of domain is more sp eci c than the rest of
option or the initargs class option
domain
initform A form whichisevaluated to pro duce a
multi metho d A method which sp ecializes on
default initial slot value Initforms are closed in their lexi
more than one argument
cal environments and the resulting closure is called an init
function An initform may b e declared for a slot in a class
de nition form using the initform slot option
new instance A newly allo cated instance which
is distinct but can b e isomorphic to other instances
initfunction A function of no arguments whose
result is used as the default value of a slot Initfunctions
re ective A system which can examine and mo d
capture the lexical environmentofaninitform declaration in
ify its own state is said to b e re ective EULISP is re ectiveto
a class de nition form
the extent that it has explicit class ob jects and metaclasses
and user extensible op erations up on them
initlist A list of alternating keywords and values
which describ es some not yet instantiated ob ject Generally
self instantiated class A class whichisanin
the keywords corresp ond to the initargs of some class
stance of itself In EULISP class is the only example
of a self instantiated class
inner dynamic Inner dynamic bindings are cre
ated by dynamic let referenced by dynamic and mo di ed setter function The function asso ciated with the
by dynamic setq Inner dynamic bindings extend and can function that accesses a place in an entity whichchanges the
shadow the dynamicall y enclosing dynamic environment value stored in that place
Programming Language EuLisp version
defclass defcondition defconstant defgeneric simple function A function comprises at least
defmacro defstruct defun an expression a set of identi ers which o ccur in the expres
sion called the parameters and the closure of the expression
All these bindings are immutable deflocal creates a muta with resp ect to the lexical environment in which it o ccurs
ble top lexical binding All such bindings are referenced by less the parameter identi ers Note this is not a de nition
variables and those made by deflocal are mo di ed by setq of the class simple function
Each mo dule de nes its own distinct top lexical environment
slot A named comp onentofanobject which can
b e accessed using the slot s accessor Each slot of an object
is describ ed bya slot description asso ciated with the class of
the object When we refer to the structure of an object this
usually means its set of slots
slot description A slot description describ es a
slot in the instances of a class This description includes the
slot s name its logical p osition in instances anda waytode
termine its default value A class s slot descriptions maybe
accessed through the function class slot descriptions A
slot description can b e either direct or inherited
slot option Akeyword and its asso ciated value
applying to one of the slots app earing in a class de nition
form for example the accessor keyword and its value
which de nes a function used to read or write the value of a
particular slot
slot sp eci cation A list of alternating keywords
and values starting with a keyword which represents a not
yet created slot description during class initiali zati on
sp ecial form A sp ecial form is a semantic prim
itive of the language In consequence any pro cessor for
example a compiler or a co de walker need b e able to pro
cess only the sp ecial forms of the language and comp ositions
of them
sp ecialize Averbal form used to describ e the cre
ation of a more sp eci c version of some entity Normally
applied to classes slot descriptions and metho ds
sp ecialize on Averbal form used to describ e re
lationship of metho ds and the classes sp eci ed in their do
mains
sub class The b ehaviour and structure de ned by
a class class are inherited byasetofclasses which are
termed subclasses of class Asubclass can b e either direct
or indirect or itself
sup erclass A class is a sup erclass of class i
class is a sub class of class A superclass can b e either
direct or indirect or itself
top dynamic Top dynamic bindings are cre
ated by defvar referenced by dynamic and mo di ed by
dynamic setq There is only one top dynamic environment
top lexical Top lexical bindings are created in the
top lexical environment of a mo dule by
Programming Language EuLisp version
Ob jects Syntax
The syntax of the classes of ob jects that can b e read by
Case is distinguish ed in eachofcharacters strings and iden
EULISP is de ned in the section of this de nition corresp ond
ti ers so that variable name and Variable name are dif
ing to the class as de ned in Table The syntax for identi
ferent but where a character is used in a p ositional num
ers corresp onds to that for symb ols
b er representation e g x Ad the case is ignored Thus
case is also signi cant in this de nition and as will b e
Table Syntax of ob jects for reading and writing
observed later all the sp ecial form and standard function
names are lower case In this section and throughout this
text the names for individua l character glyphs are those
used in ISO IEC DIS
object
character A
The minimal character set to supp ort EULISP is de ned in
float A
integer A
Table The language as de ned in this text uses only the
list A
characters given in this table Thus left hand sides of the
string A
pro ductions in this table de ne and name groups of char
symbol A
acters which are used later in this de nition decimal digit
vector A
upper letter lower letter letter other character and special
character
Table Minimal character set
decimal digit
upper letter
A B C D E F G H
I J K L M N O P
Q R S T U V W X
Y Z
lower letter
a b c d e f g h
i j k l m n o p
q r s t u v w x
y z
letter
upper letter lower letter
other character
special character
level character
decimal digit letter other character
special character
Whitespace and Comments
Whitespace characters are space and newline The newline
character is also used to represent end of record for con gu
rations providing such an input mo del thus a reference to
newline in this de nition should also b e read as a reference
to end of record The only use of whitespace is to improve
the legibil ity of programs for human readers Whitespace
separates tokens and is only signi cant in a string or when
it o ccurs escap ed within an identi er
A commentisintro duced bythecomment begin glyph called
semicolon and continues up to but do es not include
the end of the line Hence a comment cannot o ccur in the
middle of a token b ecause of the whitespace in the form of
the newline Thus a comment is equivalent to whitespace
NOTE There is no notation in EULISP for blo ck comments
Programming Language EuLisp version
Mo dules forms where the keywords indicate the interpretation of the
forms This representation allows for the addition of fur
ther keywords at other levels of the de nition and also for
The EULISP mo dule scheme has several in uences LeLisp s
implementation de ned keywords For the keywords given
mo dule system and mo dule compiler complice Haskell ML
here there is no de ned order of app earance nor is there
MIT Scheme s make environment and T s lo cales
any restriction on the numb er of times that a keyword can
app ear Multiple o ccurrences of any of the directives de ned
All bindings of ob jects in EULISP reside in some mo dule
here are treated as if there is a single directive whose form is
somewhere Also all programs in EULISP are written as one
the combination of each of the o ccurrences This de nition
or more mo dules Almost every mo dule imp orts a number
describ es the pro cessing of four keywords which are now de
of other mo dules to make its de nition meaningful These
scrib ed in detail The syntax of all the directives is given in
imp orts havetwo purp oses which are separated in EULISP
Table and an example of their use app ears in Figure
rstly the bindings needed to pro cess the syntax in which
the mo dule is written and secondly the bindings needed to
resolve the free variables in the mo dule after syntax expan
Exp ort Directive
sion These bindings are made accessible by sp ecifying which
mo dules are to b e imp orted for which purp ose in a directive
This is denoted bythekeyword export followed by a list of
at the b eginning of each mo dule The names of mo dules
names of top lexical bindings de ned in this mo dule and has
are b ound in a disjoint binding environment which is only
the e ect of making those bindings accessible to anymod
accessible via the mo dule de nition form That is to say
ule imp orting this mo dule by adding them to the external
mo dules are not rst class The b o dy of a mo dule de ni
environment of the mo dule A name clash can arise in the
tion comprises a list of directives followed by a sequence of
external environmentfrominteraction with exp osed mo d
de nitions expressions and exp ort forms
ules
The mo dule mechanism provides abstraction and securityin
a form complementary to that provided by the ob ject system
Imp ort Directive
Indeed although ob jects do supp ort data abstraction they
do not supp ort all forms of information hiding and they are
The purp ose of this directive is to sp ecify the imp orted bind
usually conceptually smaller units than mo dules A mo dule
de nes a mapping b etween a set of names and either lo cal ings which constitute part of the top lexical environmentof
a mo dule These are the explicit run time dep endencies of
or imp orted bindings of those names Most such bindings
are immutable The exception are those bindings created by the mo dule Additional run time dep endencies may arise as
a result of syntax expansion These are called implici t run
deflocal whichmay b e mo di ed by b oth the de ning and
imp orting mo dules There are no implicit imp orts into a time dep endencies
mo dule not even the sp ecial forms are available in a mo d
ule that imp orts nothing A mo dule exp orts nothing by de The imp ort directive is a sequence of module descriptors b e
and rename ing mo dule names or the lters except only
fault Mutually referential mo dules are not p ossible b ecause
a mo dule must b e de ned b efore it can b e used Hence the which denotes the union of all the names generated by each
element of the sequence A lter can in turn b e applied to a
imp ortation dep endencies form a directed acyclic graph
sequence of mo dule descriptors and so the e ect of di erent
NOTE The issue of mutually referential mo dules will b e ad
kinds of lters can b e combined by nesting them An im
dressed in a future version of the de nition of EULISP
p ort directive sp eci es either the imp ortation of a mo dule in
its entirety or the selective imp ortation of sp eci ed bindings
The pro cessing of a mo dule de nition uses three environ
from a mo dule
ments which are initiall y empty These are the top lexical
the external and the syntax environments of the mo dule
In pro cessing imp ort directives every name should b e
The top lexical environment comprises all the lo cally de ned
thought of as a pair of a module name and a local name
bindings and all the imp orted bindings The external envi
Intuitively a namelist of such pairs is generated by reference
ronment comprises all the exp osed bindings bi nd in gs from
to the mo dule name and then ltered by except only and
mo dules b eing exp osed by this mo dule but not necessarily
rename In an imp ort directive when a namelist has b een
imp orted and all the exp orted bindings which are either
ltered the names are regarded as b eing de ned in the top
lo cal or imp orted Thus the external environment might
lexical environment of the mo dule into which they have b een
not b e a subset of the top lexical environment b ecause by
imp orted A name clash can arise in the top lexical environ
virtue of an exp ose directive it can contain bindings from
ment from interaction b etween di erent imp orted mo dules
mo dules whichhave not b een imp orted This is the environ
Elements of an imp ort directiveareinterpreted as follows
ment received byany mo dule imp orting this mo dule The
syntax environment comprises all the bindings available for
except Filters the names from each module descriptor
the syntax expansion of the mo dule Each binding is repre
discarding those sp eci ed and keeping all other names
sented as a pair of a lo cal name and a mo dule name It is
The except directive is convenient when almost all of the
a static error if anytwo instances of lo cal name in any one
names exp orted by a mo dule are required since it is only
of these environments have di erent mo dule names This is
necessary to name those few that are not wanted to ex
called a name clash These environments do not all need to
clude them
exist at the same time but it is simpler for the purp oses of
de nition to describ e mo dule pro cessing as if they do
module name All the exp orted names from module
name
Directives
Filters the names from each module descriptor only
keeping only those names sp eci ed and discarding all other
names The only directiveisconvenient when only a few The list of mo dule directives is a sequence of keywords and
Programming Language EuLisp version
defmodule a module
import
module import everything from module
except binding a module al l but binding a from module
only binding b module only binding b from module
rename
binding c binding d binding d binding c al l of module but exchange
module the names of binding c and binding d
syntax
syntax module al l of the module syntax module
rename syntax a syntax b rename the binding of syntax a
syntax module of syntax module as syntax b
rename syntax c syntax a rename the binding of syntax c
syntax module of syntax module as syntax a
expose
except binding e module al l but binding e from module
module export al l of module
export
binding binding binding and three bindings from this module
export local binding a fourth binding from this module
export binding c the imported binding binding c
Figure Example of mo dule directives
defmodule eulisp level
It is also meaningful for a mo dule to include itself in an
expose
exp ose directive In this way it is p ossible to refer to all the
character collection compare condition convert copy
bindings in the mo dule b eing de ned This is convenient
double float elementary functions event
in combination with except see Section as a wayof
formatted io fixed precision integer function list
exp orting all but a few bindings in a mo dule esp ecially if
lock number object stream string symbol syntax
syntax expansion creates additional bindings whose names
table thread vector
are not known but should b e exp orted
Figure Example mo dule using expose
Syntax Directive
This directive is pro cessed in the same way as an imp ort
names exp orted by a mo dule are required since it is only
directive except that the bindings are added to the syntax
necessary to name those that are wanted to include them
environment This environment is used in the second phase
of mo dule pro cessing syntax expansion These constitute
rename Filters the names from each module descriptor
the dep endencies for the syntax expansion of the de nitions
replacing those with old name by new name Anyname
and expressions in the b o dy of the mo dule A name clash
not mentioned in the replacement list is passed unchanged
can arise in the syntax environment from interaction b etween
Note that once a name has b een replaced the new name
di erentsyntax mo dules
is not compared against the replacement list again Thus
a binding can only b e renamed once by a single rename
It is imp ortant to note that sp ecial forms are considered part
directive In consequence name exchanges are p ossible
of the syntax and they may also b e renamed
Exp ose Directive
De nitions and Expressions
De nitions in a mo dule only contain unquali ed names This is denoted by the keyword expose followed by a list of
that is local names using the ab ove terminology A top module directive s The purp ose of this directive is to allow
lexical binding is created exactly once and shared with all a mo dule to exp ort subsets of the external environments of
mo dules that imp ort its exp orted name from the mo dule that various mo dules without imp orting them itself Pro cessing
created the binding A name clash can arise in the top lexical an exp ose directive employs the same mo del as for imp orts
vironment from interaction b etween lo cal de nitions and en namely a pair of a mo dule name and a lo cal name with the
between lo cal de nitions and imp orted mo dules Only top same ltering op erations When the namelist has b een l
lexical bindings created by deflocal are mutable b oth in tered the names are added to the external environmentof
the de ning mo dule and in any imp orting mo dule It is a the mo dule b egin pro cessed A name clash can arise in the
static error to mo dify an immutable binding Expressions external environment from interaction with exp orts or b e
that is non de ning forms are collected and evaluated in or tween di erent exp osed mo dules As an example of the use
der of app earance at the end of the mo dule de nition pro cess of expose a p ossible implementation of the eulisp level
when the top lexical environment is complete that is after mo dule is shown in Figure
Programming Language EuLisp version
Table Mo dule syntax
nedstepsmaybe NOTE Additional implementation de
added here such as compilation
initialization The top lexical bindings of the mo dule
module
created ab ove are initiali zed byevaluating the forms in
defmodule module name
the b o dy of the mo dule in the order they app ear
module directives module form
module name
NOTE In this sense a mo dule can b e regarded as a gener
identifier A
alization of the labels form of this and other Lisp dialects
module directives
module directive
module directive
export identifier
Mo dule De nition
expose module descriptor
import module descriptor
defmodule syntax
syntax module descriptor
level module form
export identifier
Syntax
level expression
defining form
The syntax of a mo dule and its constituents is de ned in
progn module form
Table
module descriptor
module name
module filter
Arguments
module filter
except identifier
module name Asymb ol used to name the mo dule
module descriptor
only identifier
module directive A form sp ecifying the exp orted names
module descriptor
exp osed mo dules imp orted mo dules and syntax mo dules
rename rename pair
module descriptor
used by this mo dule
rename pair
identifier identifier
module form A sequence of de ning forms expressions
and exp ort forms
Remarks
the creation and initial iza tion of the top lexical bindings
The defmodule form de nes a mo dule named by module
The exception to this is the progn form which is descended
name and asso ciates the name module name with a mo dule
and the forms within it are treated as if the progn were
ob ject in the mo dule binding environment
not present De nitions may only app ear either at top level
within a mo dule de nition or inside anynumber of progn
NOTE Intentionally nothing is de ned ab out any relationship
forms This is sp eci ed more precisely in the grammar for a
between mo dules and les
mo dule given in Table
Examples
Mo dule Pro cessing
An example mo dule de nition with explanatory comments
is given in Figure
The following steps summarize the mo dule de nition pro
cess
directive pro cessing This is describ ed in detail in
Section This step creates and initiali zes the top
lexical syntax and external environments
syntax expansion The b o dy of the mo dule is ex
panded according to the op erators de ned in the syntax
environment constructed from the syntax directive
NOTE The semantics of syntax expansion are still under
discussion and will b e describ ed fully in a future version of
the EULISP de nition In outline however it is intended that
the mechanism should provide for hygenic expansion of forms
in sucha way that the programmer need have no knowledge
of the expansion time or run time dep endencies of the syntax
de ning mo dule
static analysis The expanded b o dy of the mo dule
is analyzed Names referenced in exp ort forms are added
to the external environment Names de ned by de ning
forms are added to the top lexical environment It is a
static error if a free identi er in an expression or de ning
form do es not have a binding in the top lexical environ
ment
Programming Language EuLisp version
object
Ob jects
character
condition
function
In EULISP every ob ject in the system has a sp eci c class
continuation
Classes themselves are rst class ob jects In this resp ect
simple function
EULISP di ers from statically typ e d ob ject oriented lan
generic function
guages suchasC and CEYX The EULISP ob ject sys
list
tem is called TELOS The facilities of the ob ject system are
cons
split across the two levels of the de nition Level sup
null
p orts the de nition of generic functions metho ds and struc
lock
tures Level provides the re ective system which supp orts
number
the meta ob ject proto col MOP introsp ection the de
integer
fixed precision integer
nition of new metaclasses and the sp ecializati on of classes
float
other than structures Metaclasses control the structure
double float
and b ehaviour of their instances and the representation of
stream
their metainstances Extensions at level suchasmulti
string
ple inheritance supp ort for the change class functionali ty
structure
of CLOS and p ersistent ob jects can b e supp orted through
symbol
metaclasses In addition metaclasses can provide new kinds
table
of classes with reduced p ower but increased e ciency the
thread
class structure class is an example No metaclass nor
vector
any op eration which could return a metaclass as a result
Figure Level initial class hierarchy
e g class of are accessible at level That supp orts the
clear distinction b etween ob ject level and metaob ject level
programming required for many optimizations
ELOS typically involve the design Programs written using T
Generic functions are de ned using the defgeneric de ning
of a class hierarchy where each class represents a category of
form which creates a named generic function in the top
entities in the problem domain and a protocol which de nes
lexical environment of the mo dule in which it app ears and
the op erations on the ob jects in the problem domain
generic lambda which creates an anonymous generic func
tion These forms are describ ed in detail later in this section
A class de nes the structure and b ehaviour of its instances
Structure is the information contained in the class s instances
Metho ds can either b e de ned at the same time as the generic
and behaviour is the way in which the instances are treated
function or else de ned separately using the defmethod
by the proto col de ned for them
macro which adds a new metho d to an existing generic func
tion This macro is describ ed in detail later in this section
The comp onents of an ob ject are called its slots Each slot
of an ob ject is de ned by its class
System De ned Classes
A proto col de nes the op erations which can b e applied to in
stances of a set of classes This proto col is typically de ned
in terms of a set of generic functions which are functions
The basic classes of EULISP are elements of the ob ject sys
whose applicatio n b ehaviour dep ends on the classes of the
tem class hierarchy whichisshown in Figure Indentation
arguments The particular class sp eci c b ehaviour is parti
indicates a sub class relationship to the class under whichthe
tioned into separate units called methods A metho d is not
line has b een indented for example condition is a sub
a function itself but is a closed expression which is a com
class of object The names given here corresp ond to the
p onent of a generic function
bindings of names to classes as they are exp orted from the
level mo dules Classes directly relevant to the ob ject sys
Generic functions replace the send construct found in many
tem are describ ed in this section while others are describ ed
ob ject oriented languages In contrast to sending a message
in corresp onding sections e g condition is describ ed in
to a particular ob ject whichitmust knowhow to handle
the conditions section
the metho d executed by a generic function is determined by
all of its arguments Metho ds which sp ecialize on more than
In this de nition unless otherwise sp eci ed classes declared
one of their arguments are called multi methods
to b e sub classes of other classes may b e indirect sub classes
Classes not declared to b e in a sub class relationship are dis
Inheritance is provided through classes Slots and metho ds
joint Furthermore unless otherwise sp eci ed all ob jects
de ned for a class will also b e de ned for its sub classes but
declared to b e of a certain class may b e indirect instances of
a sub class may sp ecialize them In practice this means that
that class
an instance of a class will contain all the slots de ned di
rectly in the class as well as all of those de ned in the class s
sup erclasses In addition a metho d sp ecialized on a particu
lar class will b e applicable to direct and indirect instances of
object class
this class The inheritance rules the applicabil i ty of meth
o ds and the generic dispatch are describ ed in detail later in
this section The ro ot of the inheritance hierarchy object de nes
the basic metho ds for initial izati on and external represen
Classes are de ned using the defstruct and tation of ob jects No initializa tion options are sp eci ed for
defcondition de ning forms object
Programming Language EuLisp version
Table defstruct syntax
structure class
defstruct form
The default sup erclass of structure classes All classes de
defstruct class name superclass name
slot description list class option
ned using the defstruct form are direct or indirect sub
class name
classes of structure Thus this class is sp ecializabl e by
identifier A
user de ned classes at level No initoptions are sp eci ed
superclass name
for structure
identifier A
slot description list
slot decsription
slot description
telos condition condition
slot name
slot name slot option
slot name
This is the general condition class for conditions arising from
identifier A
op erations in the ob ject system
slot option
initarg identifier A
initform level expression
Single Inheritance
reader identifier A
writer identifier A
accessor identifier A
TELOS level provides only single inheritance meaning that
class option
a class can have exactly one direct sup erclass but indef
initargs identifier
initely many direct sub classes In fact all classes in the
constructor identifier
level class inheritance tree have exactly one direct sup er
initarg name
class except the ro ot class object which has no direct
predicate identifier A
sup erclass
Each class has a class precedence list CPL a linearized list
of all its sup erclasses which de nes the classes from which
slot spec A list of slot sp eci cations see b elow
the class inherits structure and b ehaviour For single inher
itance classes this list is de ned recursively as follows comprising either a slot name or a list of a slot name fol
lowed by some slot options
a the CPL of object is a list of one element containing
class option A sequence of keys and values see b elow
object itself
which taken together apply to the class as a whole
b the CPL of any other class is a list of classes b eginning
with the class itself followed by the elements of the CPL
Remarks
of its direct sup erclass whichis object by default
defstruct creates a new structure class Structure classes
supp ort single inheritance as describ ed ab ove Neither class
The class precedence list controls system de ned proto cols
rede nition nor changing the class of an instance is supp orted
concerning
by structure classes
a inheritance of slot and class options when initializi ng
The slot option s are interpreted as follows
a class
initarg identi er The value of this option is an identi
b metho d lo okup and generic dispatch when applying a
er naming a symb ol which is the name of an argumentto
generic function
b e supplied in the init option s of a call to make on the new
class The value of this argument in the call to make is the
initial value of the slot This option must only b e sp eci
De ning Classes
ed once for a particular slot The same initarg name may
b e used for several slots in which case they will share the
defstruct de ning form
same initial value if the initarg is given to make Sub classes
inherit the initarg Eachslotmust haveatmostoneini
targ includin g the inherited one That means a sub class
Syntax
can not shadow or add a new initarg if a sup erclass has
already de ned one
The syntax for defstruct is given in Table
initform form The value of this option is a form which
is evaluated as the default value of the slot to b e used if
Arguments
make no initarg is de ned for the slot or given to a call to
The form is evaluated in the lexical environment of the call
class name A symb ol naming a binding to b e initiali zed
to defstruct and the dynamic environment of the call to
with the new structure class The binding is immutable
In combination with the guarantee that the b ehaviour of
superclass name A symb ol naming a binding of a class
generic functions cannot b e mo di ed once it has b een de ned
to b e used as the direct sup erclass of the new structure
due to no supp ort for metho d removal nor metho d combination
this imbues level programs with static semantics class
Programming Language EuLisp version
make The form is evaluated eachtimemake is called and De ning Generic Functions and Metho ds
the default value is called for The order of evaluation of
the initforms in all the slots is determined by initialize
defgeneric de ning form
This option must only b e sp eci ed once for a particular
slot Sub classes inherit the initform However a more
sp eci c form may b e sp eci ed in a sub class which will
Syntax
shadow the inherited one
reader identi er The value is the identi er of the vari
defgeneric form
able to which the reader function will b e b ound The
defgeneric gf name gf lambda list
binding is immutable The reader function is a means to
level init option
access the slot The reader function is a function of one
gf name
argument which should b e an instance of the new class
identifier A
gf lambda list No writer function is automatically b ound with this op
specialized lambda list
tion This option can b e sp eci ed more than once for a
level init option
slot creating several bindings for the same reader func
method method description
tion It is a static error to sp ecify the same reader writer
method description
or accessor name for two di erent slots
specialized lambda list form
specialized lambda list
specialized parameter
writer identi er The value is the identi er of the vari
specialized parameter
able to which the writer function will b e b ound The bind
identifier A
ing is immutable The writer function is a means to change
specialized parameter
the slot value The creation of the writer is analogous to
identifier class name A
that of the reader function The writer function is a func
identifier A
tion of two arguments the rst should b e an instance of
the new class and the second can b e anynewvalue for the
slot This option can b e sp eci ed more than once for a
slot It is a static error to sp ecify the same reader writer
Arguments
or accessor name for two di erent slots
gf name One of a symb ol or a form denoting a setter
accessor identi er The value is the identi er of the
function or a converter function
variable to which the reader function will b e b ound In ad
dition the use of this slot option causes the writer function
gen lambda list The parameter list of the generic func
to b e asso ciated to the reader via the setter mechanism
tion whichmay b e sp ecialized to restrict the domain of
This option can b e sp eci ed more than once for a slot
metho ds to b e attached to the generic function
It is a static error to sp ecify the same reader writer or
accessor name for two di erent slots
level init option Options as sp eci ed b elow
The class options are interpreted as follows
Remarks
This de ning form de nes a new generic function The re
initargs list The value of this option is a list of iden
sulting generic function will b e b ound to gf name The sec
ti ers naming symb ols which extend the inherited names
ond argument is the formal parameter list The metho d s
of arguments to b e supplied in the init option sofacall
sp ecialized lamba list must b e congruenttothatofthe
to make on the new class Initargs are inherited by union
generic function Twolamb da lists are said to b e congru
The values of all legal arguments in the call to make are
ent i
the initial values of corresp onding slots if they name a slot
initarg or are ignored by the default initialize metho d
a b oth have the same numb er of formal parameters and
otherwise This option must only b e sp eci ed once for a
class
b if one lamb da list has a rest formal parameter then the
other lamb da list has a rest formal parameter to o and vice
versa
constructor constructor spec Creates a constructor
function for the new class The constructor sp eci cation
An error is signalled condition
gives the name to which the constructor function will b e
class non congruent lambda lists ifany metho d de
b ound followed by a sequence of legal initargs for the class
ned on this generic function do es not havealamb da list
The new function creates an instance of the class and lls
congruent to that of the generic function
in the slots according to the matchbetween the sp eci ed
initargs and the given arguments to the constructor func
An error is
tion This option may b e sp eci ed anynumb er of times
signalled condition class incompatible method domain
for a class
if the metho d s sp ecialized lamb da list widens the domain of
b da lists of all the generic function In other words the lam
predicate identi er Creates a function which tests
metho ds must sp ecialize on sub classes of the classes in the
whether an ob ject is an instance of the new class The
lamb da list of the generic function
predicate sp eci cation gives the name to which the predi
cate function will b e b ound This option may b e sp eci ed
An error is signalled condition
anynumb er of times for a class
class method domain clash ifany metho ds de ned on
Programming Language EuLisp version
Table defgeneric rewrite rules
defgeneric identi er gf lambda list defconstant identi er
flevel init optiong generic lambda gf lambda list flevel init optiong
defgeneric setter identi er gf lambda list setter setter identi er
flevel init optiong generic lambda gf lambdalist flevel init optiong
defgeneric converter identi er gf lambda list setter converter identi er
flevel init optiong generic lambda gf lambda list level init optiong
this generic function have the same domain These condi
tions apply b oth to metho ds de ned at the same time as the
defmethod form
generic function and to any metho ds added subsequently by
defmethod gf locator
specialized lambda list
defmethod Aninit option is an identi er followed by a cor
form
resp onding value
gf locator
identifier
An error is signalled condition class
setter identifier
no applicable method if an attempt is made to apply
converter identifier
a generic function which has no applicabl e metho ds for the
classes of the arguments supplied
The init option is
Remarks
This macro is used for de ning new metho ds on generic
method method spec This option is followed by a
functions A new metho d ob ject is de ned with the sp ec
metho d description A metho d description is a list com
i ed b o dy and with the domain given by the sp ecialized
prising the sp ecialized lamb da list of the metho d which
lamb da list This metho d is added to the generic func
denotes the domain and a sequence of forms denoting
tion b ound to gf name whichisanidenti er or a form
the metho d b o dy The metho d b o dy is closed in the lex
denoting a setter function or a converter function If
ical environmentinwhich the generic function de nition
the sp ecialized lamb da l ist is not congruent with that of
app ears This option may b e sp eci ed more than once
the generic function an error is signalled condition class
non congruent lambda lists An error is signalled
The rewrite rules for defgeneric are given in Table condition class incompatible method domain if the
metho d s sp ecialized lamb da list would widen the domain
of the generic function If there is a metho d with the same
domain already de ned on this gneric function an error is
signalled condition class method domain clash
Examples
In the following example of the use of defgeneric a generic
function named gf is de ned with three metho ds attached
generic lambda macro
to it The domain of gf is constrained to b e object
class a In consequence each metho d added to the
generic function b oth here and later by defmethod must
have a domain which is a sub class of object class a
Syntax
whichistosay that class c class e and class g
must all b e sub classes of class a
generic lambda form
generic lambda gflambdalist
defgeneric gf arg arg class a
level init option
method m arg class b m arg class c
method m arg class d m arg class e
method m arg class f m arg class g
Remarks
generic lambda creates and returns an anonymous generic
function that can b e applied immediately muchlike the nor
mal lambda Thegen lambda list and the init option s are in
terpreted exactly as for the level de nition of defgeneric See also defmethod generic lambda
Examples
In the following example an anonymous version of gf see
defmethod macro
defgeneric ab ove is de ned In all other resp ects the re
sulting ob ject is the same as gf
generic lambda arg object arg class a
method m arg class b m arg class c
Syntax
method m arg class d m arg class e
Programming Language EuLisp version
Remarks method m arg class f m arg class g
Signalled by one of defgeneric defmethod or
generic lambda if there would b e metho ds with the same
domain attached to the generic function
See also defgeneric
Sp ecializing Metho ds
no applicable method telos condition
The following two op erators are used to sp ecialize more gen
eral metho ds The more sp ecialized metho d can do some
additional computation b efore calling these op erators and
Initializatio n Options
can then carry out further computation b efore returning It
is an error to use either of these op erators outside a metho d
generic function The generic function whichwas ap
body Argument bindings inside metho ds are immutable
plied
Therefore an argument inside a metho d retains its sp ecial
ized class throughout the pro cessing of the metho d
arguments list The arguments of the generic function
whichwas applied
call next method special form
Remarks
Signalled by a generic function when there is no metho d
Syntax
which is applicabl e to the arguments
call next method
incompatible method domain telos condition
Result
The result of calling the next most sp eci c applicabl e
Initializatio n Options
metho d
generic function The generic function to b e extended
Remarks
method method The metho d to b e added
The next most sp eci c applicable metho d is called with the
same arguments as the current metho d An error is signalled
condition class no next method if there is no next most
Remarks
sp eci c metho d
Signalled by one of defgeneric defmethod or
generic lambda if the domain of the metho d would not b e
a sub domain of the generic function s domain
next method p special form
Syntax
non congruent lambda lists telos condition
next method p
Initializatio n Options
Result
generic function The generic function to b e extended
If there is a next most sp eci c metho d next method p re
turns a non value otherwise it returns
method method The metho d to b e added
Remarks
no next method telos condition
Signalled by one of
defgeneric defmethod or generic lambda if the lambda
Initializatio n Options
list of the metho d is not congruent to that of the generic
function
method method The metho d which called
call next method
method domain clash telos condition
operand list list A list of the arguments to havebeen
passed to the next metho d
Initializatio n Options
Remarks
generic function The generic function to b e extended
Signalled by call next method ifthereisnonextmostspe
methods list The metho ds with the same domain
ci c metho d
Programming Language EuLisp version
The rst two steps are usually called methodlookup and the Metho d Lo okup and Generic Dispatch
rst four are usually called generic dispatch
The system de ned metho d lo okup and generic function dis
patch is purely class based eql metho ds known from CLOS
Creating and Initializing Ob jects
are excluded
Ob jects can b e created by calling
The application b ehaviour of a generic function can b e de
scrib ed in terms of methodlookup and generic dispatch The
constructors prede ned or user de ned or
metho d lo okup determines
make the general constructor function or
a which metho ds attached to the generic function are
applicable to the supplied arguments and
allocate the general allo cator function
b the linear order of the applicabl e metho ds with re
sp ect to classes of the arguments and the argument prece
make function
dence order
A class C is called morespeci c than class C with respect
Arguments
to C i C app ears b efore C in the class precedence list
CPL of C
class The class of the ob ject to create
Two additional concepts are needed to explain the pro
key obj key obj Initializa tion arguments
n n
cesses of metho d lo okup and generic dispatch i whether a
metho d is applicable ii how speci c it is in relation to the
other applicable metho ds The de nitions of each of these
Result
termsisnow given
An instance of class
A metho d with the domain D D list is ap
m
plicable to the arguments a a a a if the class
m m n
Remarks
of each argument C is a sub class of D whichistosay D
i i i
The general constructor make creates a new ob ject calling
is a member of C s class precedence list
i
allocate and initiali zes it by calling initialize make re
turns whatever allocate returns as its result
A metho d M with the domain D D list
m
is morespeci c than a metho d M with the domain
D D list with respect to the arguments
m
allocate function
a a a a i there exists an i m so that
m m n
D is more sp eci c than D with resp ect to C the class of
i i i
and for all j i D is not more sp eci c than a
i j
Arguments
D with resp ect to C the class of a
j j j
class A structure class
Now with the ab ove de nitions we can describ e
the applicati on b ehaviour of a generic function f
initlist A list of initiali zati on arguments
a a a a
m m n
a Select the metho ds applicabl e to a a a a
m m n
Result
from all metho ds attached to f
A new uninitial i zed direct instance of the rst argument
b Sort the applicable metho ds M M into decreasing
k
order of sp eci city using left to right argument precedence
Remarks
order to resolve otherwise equally sp eci c metho ds
The class must b e a structure class the initlist is ignored
The b ehaviour of allocate is extended at level for classes
c If call next method app ears in one of the metho d
not accessible at level The level b ehaviour is not a ected
b o dies make the sorted list of applicable metho ds avail
by the level extension
able for it
d Apply the most sp eci c metho d on
initialize generic function
a a a a
m m n
e Return the result of the previous step
Generic Arguments
This de nition is required when multiple inheritance comes
object object The ob ject to initialize
into play Then two classes have to b e compared with resp ect
to a third class even if they are not related to each other via
initlist The list of initiali zati on arguments
the sub class relationship Although multiple inheritance is not
provided at level the metho d lo okup proto col is indep endent
of the inheritance strategy de ned on classes It dep ends on the
Result
class precedence lists of the domains of metho ds attached to the
generic function and the argument classes involved The initialize d ob ject
Programming Language EuLisp version
Remarks Concurrency
Initializes an ob ject and returns the initiali zed ob ject as the
result It is called by make on a new uninitia li zed ob ject The basic elements of parallel pro cessing in EULISP are pro
cesses and mutual exclusion which are provided bythe
created by calling allocate
classes thread and lock resp ectively
Users may extend initialize by de ning metho ds sp ecial
The A thread is allo cated and initialized by calling make
izing on newly de ned classes which are structure classes at
initarg of a thread sp eci es the initial function whichis
level
where execution starts the rst time the thread is dispatched
by the scheduler In this discussion four states of a thread are
identi ed new running aborted and nished These are for
initialize method
conceptual purp oses only and a EuLisp program cannot dis
tinguish b etween new and running or b etween ab orted and
Sp ecialized Arguments
nished Although accessing the result of a thread would
p ermit such a distinction retrosp ectively since an ab orted
object object The ob ject to initialize
thread will cause a condition to b e signalled on the access
ing thread and a nished thread will not In practice the
initlist The list of initial izati on arguments
running state is likely to haveseveral internal states but
these distinctions and the information ab out a thread s cur
rent state can serve no useful purp ose to a running program
Result
since the information may b e incorrect as so on as it is known
The initializ ed ob ject
The initial state of a thread is new The union of the two
nal states is known as determined Although a program can
nd out whether a thread is determined or not by means of
Remarks
wait with a timeout of t denoting a p oll the information
This is the default metho d attached to initialize This
is only useful if the thread has b een determined
metho d p erforms the following steps
A thread is made available for dispatchby starting it using
a Checks if the supplied initargs are legal and signals
the function thread start whichchanges its state from new
an error otherwise Legal initargs are those sp eci ed in
to running After running a thread b ecomes either nished
the class de nition directly or inherited from a sup erclass
or ab orted When a thread is nished the result of the
An initarg may b e sp eci ed as a slot option or as a class
initial function may b e accessed using thread value Ifa
option
thread is ab orted which can only o ccur as a result of a signal
handled by the default handler installed when the thread is
b Initializes the slots of the ob ject according to the
created then thread value will signal the condition that
initarg if supplied or according to the most sp eci c
ab orted the thread on the thread accessing the value Note
initform if sp eci ed Otherwise the slot remains un
that thread value susp ends the calling thread if the thread
b ound
whose result is sought is not determined
Legal initargs which do not initialize a slot are ignored by
While a thread is running its progress can b e susp ended
the default initialize metho d More sp eci c metho ds may
by accessing a lo c k by a stream op eration or by calling
handle these initargs and call the default metho d by calling
thread value on an undetermined thread In each of these
call next method
cases thread reschedule is called to allow another thread
to execute This function may also b e called voluntarily
Progress can resume when the lo ck b ecomes unlo cked the in
Accessing Slots
put output op eration completes or the undetermined thread
b ecomes determined
Ob ject comp onents slots can b e accessed using reader and
writer functions accessors only For system de ned ob ject
The actions of a thread can b e in uenced externally by
classes there are prede ned readers and writers Some of
signal This function registers a condition to b e signalled
the writers are accessible using the setter function If there
no later than when the sp eci ed thread is rescheduled for
is no writer for a slot its value cannot b e changed When
execution when thread reschedule returns The condi
users de ne new classes they can sp ecify which readers and
tion must b e an instance of thread condition Conditions
writers should b e accessible in a mo dule and bywhich bind
are delivered to the thread in order of receipt This ordering
ing Accessor bindings are not exp orted automatically when
requirement is only imp ortant in the case of a thread sending
a class binding is exp orted They can only b e exp orted
more than one signal to the same thread but in other cir
explicitly
cumstances the delivery order cannot b e veri ed A signal
on a determined thread has no discernable e ect on either
the signalled or signalli ng thread unless the condition is not
an instance of thread condition in which case an error
is signalled on the signalli ng thread See also Section
Alock is an abstract data typ e protecting a binary value
which denotes whether the lo ckislocked or unlo cked The
op erations on a lo ck are lock and unlock Executing a lock
op eration will eventually give the calling thread exclusive
control of a lo ck The unlock op eration unlo cks the lo ckso
that either a thread subsequently calling lock or one of the
Programming Language EuLisp version
Aweak but su cient guaranteeisthatifany thread resched threads which has already called lock on the lo ck can gain
ules in nitely often then every other thread will b e scheduled exclusive access
in nitely often Hence if a thread is waiting for shared data
NOTE Itisintended that implementationsoflocks based on
to b e changed by another thread and is using a lo ck the other
spin lo cks semaphores or channels should all b e capable of sat
thread is guaranteed to have the opp ortunitytochange the
isfying the ab ove description However to b e a conforming im
data If it is not using a lo ck the fairness guarantee en
plementation the use of a spin lo ckmust observe the fairness re
sures that in the same scenario the following lo op will exit
quirement which demands that b etween attempts to acquire the
eventually
lo ck control must b e ceded to the scheduler
while data thread reschedule
The programming mo del is that of concurrently executing
threads regardless of whether the con guration is a multi
pro cessor or not with some constraints and some weak fair
ness guarantees
Threads
a A pro cessor is free to use run to completion timeslic
ing and or concurrent execution
The de ned name of this mo dule is thread This section
de nes the op erations on threads
b A conforming program must assume the p ossibilityof
concurrent execution of threads and will have the same
semantics in all cases see discussion of fairness which fol
thread class
lows
c The default condition handler for a new thread when
The class of all instances of thread
invoked will change the state of the thread to aborted
save the signalled condition and reschedule the thread
Initializatio n Options
d A continuation must only b e called from within its
dynamic extent This do es not include threads created
init function fn an instance of function which
within the dynamic extent An error is signalled condi
will b e called when the resulting thread is started by
tion class wrong thread continuation if a continu
thread start
ation is called on a thread other than the one on whic hit
was created
threadp function
e The lexical environment inner and top asso ciated
with the initial function may b e shared as is the top
dynamic environment but each thread has a distinct
Arguments
inner dynamic environment In consequence any mo di
cations of bindings in the lexical environment or in the
object An ob ject to examine
top dynamic environment should b e mediated bylocks to
avoid non deterministi c b ehaviour
Result
f The creation and starting of a thread represent
The supplied argument if it is an instance of thread oth
changes to the state of the pro cessor and as such are not
erwise
a ected by the pro cessor s handling of errors signalled sub
sequently on the creating starting thread c f streams
That is to say a non lo cal exit to a p oint dynamicall y out
thread reschedule function
side the creation of the subsidiary thread has no default
e ect on the subsidiary thread
This function takes no arguments
g The b ehaviour of i o on the same stream bymultiple
threads is unde ned unless it is mediated by explicit lo cks
Result
The parallel semantics are preserved on a sequential run to
The result is
completion implementation by requiring communication b e
tween threads to use only thread primitives and shared data
protected bylocks b oth the thread primitives and lo cks will
Remarks
cause rescheduling so other threads can b e assumed to have
achance of execution
This function is called for side e ect only and may cause the
thread which calls it to b e susp ended while other threads
There is no guarantee ab out which thread is selected next
are run In addition if the thread s condition queue is not
However a fairness guarantee is needed to provide the il
empty the rst condition is removed from the queue and
lusion that every other thread is running A strong guar
signalled on the thread The resume continuation of the
antee would ensure that every other thread gets scheduled
signal will b e one which will eventually call the continuation
b efore a thread whichreschedules itself is scheduled again
of the call to thread reschedule
Suchascheme is usually called round robin This could
vided by a parallel imple b e stronger than the guarantee pro
mentation or the scheduler of the host op erating system and See also thread value signal and Section
cannot b e mandated in this de nition for details of conditions and signalli ng
Programming Language EuLisp version
Result
current thread function
Result is either thread or Iftimeout is the result
is thread if it is determined If timeout is t thread sus
p ends until thread is determined and the result is guaran
This function takes no arguments
teed to b e thread Iftimeout is a non negativeinteger the
call blo cks until either thread is determined in which case
the result is thread oruntil the timeout p erio d is reached
Result
in which case the result is whichev er is the so oner The
The thread on which current thread was executed
units for the non negativeinteger timeout are the number
of clo ckticks to wait The implementation de ne d constant
ticks per second is used to make timeout p erio ds pro ces
thread start function
sor indep endent
Arguments
See also wait and ticks per second Sec
tion
thread the thread to b e started whichmust b e new If
thread is not new an error is signalled condition class
thread already started
thread condition condition
obj obj values to b e passed as the arguments to the
n
initial function of thread
Initializatio n Options
Result
current thread thread The thread whichissignalling
The thread whichwas supplied as the rst argument
the condition
Remarks
Remarks
The state of thread is changed to running The values obj
This is the general condition class for all conditions arising
to obj will b e passed as arguments to the initial function of
n
from thread op erations
thread
thread value function
wrong thread continuation thread condition
Arguments
Initializatio n Options
thread the thread whose nished value is to b e accessed
continuation continuation Acontinuation
Result
thread thread The thread on which continuation was
created
The result of the initial function applied to the arguments
passed from thread start However if a condition is sig
nalled on thread which is handled by the default handler
the condition will now b e signalled on the thread calling
Remarks
thread value that is the condition will b e propagated to
Signalled if the given continuation is called on a thread other
the accessing thread
than the one on whichitwas created
Remarks
thread already started thread condition
If thread is not determined each thread calling thread value
is susp ended until thread is determined when each will either
get the thread s value or signal the condition
Initializati on Options
See also thread reschedule signal
thread thread A thread
wait method
Remarks
Signalled by thread start if the given thread has b een
started already
Sp ecialized Arguments
thread thread The thread on whichtowait
Lo cks
timeout object The timeout p erio d which is sp ec
i ed by one of t and non negativeinteger
The de ned name of this mo dule is lock
Programming Language EuLisp version
Conditions
lock class
The de ned name of this mo dule is condition
The class of all instances of lock This class has no init
The condition system was in uenced by the Common Lisp
options The result of calling make on lock is a new op en
error system and the Standard ML exception mechanism
lo ck
It is a simpli cati on of the former and an extension of the lat
ter Following standard practice this text de nes the actions
of functions in terms of their normal b ehaviour Where an
lockp function
exceptional b ehaviour might arise this has b een de ned in
terms of a condition However not all exceptional situations
are errors Following Pitman weuse condition to b e a kind
Arguments
of o ccasion in a program when an exceptional situation has
b een signalled An error is a kind of condition error and
object An ob ject to examine
condition are also used as terms for the ob jects that rep
resent exceptional situations A condition can b e signalled
continuably by passing a continuation for the resumption to
Result
signal If a continuation is not supplied then the condition
The supplied argumentifitisaninstanceoflock otherwise
cannot b e continued
These two categories are characterized as follows
lock function
a A condition might b e signalled when some limit has
b een transgressed and some correctiveactionisneeded
b efore pro cessing can resume For example memory zone
Arguments
exhaustion on attempting to heap allo cate an item can
b e corrected by calling the memory managementscheme
lock the lo ck to b e acquired
ver dead space However if no space was recov to reco
ered a new kind of condition has arisen Another example
arises in the use of IEEE oating p oint arithmetic where
Result
a condition might b e signalled to indicate divergence of
The lo ck supplied as argument
an op eration A condition should b e signalled continuably
when there is a strategy for recovery from the condition
Remarks
b Alternatively a condition might b e signalled when
Executing a lock op eration will eventually give the calling
some catastrophic situation is recognized such as the
thread exclusivecontrol of lock A consequence of calling
memory manager b eing unable to allo cate more memory or
lock is that a condition from another thread may b e sig
unable to recover su cient memory from that already al
nalled on this thread Such a condition will b e signalled
lo cated A condition should b e signalled non continuably
b efore lock has b een acquired so a thread whichdoesnot
when there is no reasonable way to resume pro cessing
handle the condition will not lead to starvation the con
dition will b e signalled continuably so that the pro cess of
A condition class is de ned using defcondition see Sec
acquiring the lo ckmay continue after the condition has b een
tion The de nition of a condition causes the creation
handled
of a new class of condition A condition is signalled using
the function signal which has two required arguments and
one optional argument an instance of a condition a re
See also unlock and Section for details of con
sume continuation or the empty list the latter signifying a
ditions and signalli ng
non continuable signal and a thread A condition can b e
handled using the sp ecial form with handler whichtakes a
function the handler function and a sequence of forms to
unlock function
b e protected The initial condition class hierarchy is shown
in Figure
Arguments
Condition Classes
lock the lo ck to b e released
condition class
Result
The lo ck supplied as argument
Initializatio n Options
message string A string containing information
Remarks
which should p ertain to the situation which caused the
The unlock op eration unlo cks lock so that either a thread
condition to b e signalled
subsequently calling lock or one of the threads which has
already called lock on the lo ck can gain exclusive access
Remarks
The class which is the sup erclass of all condition classes See also lock
Programming Language EuLisp version
condition
Result
execution condition
invalid operator
Returns object if it is a condition otherwise
cannot update setter
no setter
environment condition
arithmetic condition
initialize method
division by zero
conversion condition
no converter
Sp ecialized Arguments
stream condition
syntax error
condition condition a condition
thread condition
thread already started
initlist A list of initiali zati on options as follows
wrong thread continuation
wrong condition class
telos condition
message string A string containing information
no next method
which should p ertain to the situation which caused the
non congruent lambda lists
condition to b e signalled
n incompatible method domai
no applicable method
method domain clash
Result
Figure Level initial condition class hierarchy
A new initiali zed condition
Remarks
execution condition condition
First calls call next method to carry out initiali zatio n sp ec
i ed by sup erclasses then do es the condition sp eci c ini
tialization The following init option is recognized bythis
This is the general condition class for conditions arising from
metho d
the execution of programs by the pro cessor
message string A string which should contain informa
tion ab out the condition that has arisen
domain condition execution condition
Initializatio n Options
defcondition de ning form
argument object An argument whichwas not of the
exp ected class or outside a de ned range and therefore
Syntax
lead to the signalli ng of this condition
defcondition condition class name superclass name init
option
range condition execution condition
Arguments
Initializatio n Options
condition class name Asymb ol naming a binding to b e
initiali zed with the new condition class
result object A result whichwas not of the ex
p ected class or outside a de ned range and therefore lead
superclass name A symb ol naming a binding of a class
to the signalli ng of this condition
to b e used as the sup erclass of the new condition class
init option A sequence of symb ols and expressions
to b e passed to then generic functions allocate and
environment condition condition
initialize
This is the general condition class for conditions arising from
the environment of the pro cessor
Remarks
This de ning form de nes a new condition class The rst
argument is the name to which the new condition class will
conditionp function
b e b ound The second is the name of the sup erclass of the
new condition class and an init option is an identi er fol
lowed by its default initial value If superclass name is
Arguments
the sup erclass is taken to b e condition Otherwise
superclass name must b e condition or the name of one of
object An ob ject to examine
its sub classes
Programming Language EuLisp version
condition condition A condition Condition Handling
Signalled by signal if the given condition is not an instance
Conditions are handled with a function called a hand ler
of the condition class thread condition
Handlers are established dynamicall y and have dynamic
scop e and extent Thus when a condition is signalled the
pro cessor will call the dynamically closest handler This can
accept resume or decline the condition see with handler
with handler special form
for a full discussion and de nition of this terminology If it
declines then the next dynamically closest handler is called
Syntax
and so on until a handler accepts or resumes the condition
It is the rst handler accepting the condition that is used
with handler hand ler function protected form
and this may not necessarily b e the most sp eci c Handlers
are established by the sp ecial form with handler
Arguments
hand ler function A function or a generic function which
signal function
will b e called if a condition is signalled during the dy
namic extentofprotected forms A handler function
takes two arguments a condition and a resume func
Arguments
tion continuati on The condition is the condition ob ject
that was passed to signal as its rst argument The re
condition The condition to b e signalled
sume continuation is the continuation or that was
given to signal as its second argument
function The function to b e called if the condition is
handled and resumed that is to say the condition is con
protected form The sequence of forms whose execution
tinuable or otherwise
is protected by the hand ler function sp eci ed ab ove
thread If this argument is not supplied the condition
is signalled on the thread which called signal otherwise
Result
thread indicates the thread on which condition is to b e
The value of the last form in the sequence of protected forms
signalled
Remarks
Result
A with handler form is evaluated in four steps
signal should never return It is an error to call signal s
continuation
a The new hand ler function is constructed and identi es
the dynamicall y closest handler
Remarks
b The dynamicall y closest handler is shadowed by the
Called to indicate that a sp eci ed condition has arisen during
establishment of the new hand ler function
the execution of a program
c The sequence of protected formsisevaluated in order
If the third argument is not supplied signal calls the dy
and the value of the last one is returned as the result of
namically closest handler with condition and continuation
the with handler expression
If the second argument is a sub class of function itisthe
resume continuation to b e used in the case of a handler de
d the hand ler function is disestablish ed and the previ
ciding to resume from a continuable condition If the second
ous handler is no longer shadowed
argumentis it indicates that the condition was signalled
as a non continuable condition i n this way the handler is
The ab ove is the normal b ehaviour of with handler The
informed of the signaler s intention
exceptional b ehaviour of with handler happ ens when there
is a call to signal during the evaluation of protected form
If the third argument is supplied signal registers the
signal calls the dynamicall y closest hand ler function pass
The sp eci ed condition to b e signalled on thread
ing on the rst two arguments given to signal The hand ler
condition must b e an instance of the condition class
function is executed in the dynamic extent of the call to
thread condition otherwise an error is signalled condi
signal However any signals o ccurring during the exe
tion class wrong condition class on the thread calling
cution of hand ler function are dealt with by the dynami
signal Asignal on a determined thread has no e ect on
cally closest handler outside the extent of the form which
either the signalled or signallin g thread except in the case of
established hand ler function Ahand ler function takes one
the ab ove error
of three actions
Return This causes the next closest enclosing a
See also thread reschedule thread value
hand ler function to b e called passing on the condition
with handler
and the resume continuation This is termed declining
the condition The situation when there is no next closest
enclosing handler is discussed later
wrong condition class thread condition
b Call the resume continuation This action mightbe
taken if the condition is recognized by the handler function Initializ atio n Options
Programming Language EuLisp version
let cc accept
signal with an instance of a condition of condition class
with handler
initiali zed from init option s the error message and a resume
generic lambda
continuation value of signifying that the condition was
condition condition resume function
not signalled continuably
method
c condition resume
cond
seriousp c
cerror function
serious error exit from with hand ler accept
accept
fixablep c
Arguments
xable error resume
resume fix c
error message a string containing relevant information
t
otherwise by omission let another hand ler deal
condition class the class of condition to b e signalled
with it decline
init option a sequence of options to b e passed to
the protected expression
something which might signal an error initialize instance when making the instance of con
dition
Figure Illustration of handler actions
Result
The result is
and might b e preceded by some corrective action This is
termed resuming the condition
Remarks
The cerror function signals a continuable error It calls
c Not return and not call the resume continuation This
signal with an instance of a condition of condition class
action mightbetaken if the condition is recognized by the
initiali zed from init option s the error message and a resume
handler function and might b e preceded by some corrective
continuation value which is the continuation of the cerror
action b efore some kind of transfer of control This is
expression A non resume continuation signi es that the
termed accepting the condition
condition has b een signalled continuably
It is an error if the condition is declined and there is no next
closest enclosing handler In this circumstance the identi ed
error is delivered to the con guration to b e dealt with in an
implementation de ned way Errors arising in the dynamic
extent of the handler function are signalled in the dynamic
signal but are handled in the enclosing extent of the original
dynamic extent of the handler
Examples
An illustration of the use of all three cases is given in Fig
ure
See also signal
error function
Arguments
error message a string containing relevant information
condition class the class of condition to b e signalled
init option a sequence of options to b e passed to
initialize instance when making the instance of con
dition
Result
The result is
Remarks
The error function signals a non continuabl e error It calls
Programming Language EuLisp version
Expressions De nitions and Control
t symbol
Forms
This section gives the syntax of well formed expressions and
Remarks
describ es the semantics of the sp ecial forms functions and
macros of the level language In the case of level macros
The symbol t is de ned to b e immutably b ound to the sym
the description includes a set of expansion rules However
bol t Thismay b e used to denote the abstract b o olean value
these descriptions are not prescriptiveofany pro cessor and
true but so mayany other value than
a conforming program cannot rely on adherence to these ex
pansions
symbol syntax
Simple Expressions
The current lexical binding of symbol is returned A symbol
can also name a de ned constant that is an immutable
constant syntax
top lexical binding
There are two kinds of constants literal constants and de
ned constants Only the rst kind are considered here A
deflocal de ning form
literal constant isanumb er a string a character or the
empty list The result of pro cessing such a literal constant
is the constant itself that is it denotes itself
Syntax
Examples
deflocal form
the empty list
deflocal identifier form
a xed precision integer
a acharacter
abc a string
Arguments
defconstant de ning form
identi er Asymb ol naming a binding containing the
value of form
form The form whose value will b e stored in the binding Syntax
of identi er
defconstant form
defconstant identifier form
Remarks
The value of form is stored in the top lexical binding of iden
ti er The binding created byadeflocal form is mutable
Arguments
See also setq
identi er A symb ol naming an immutable top lexical
binding to b e initiali zed with the value of form
form The form whose value will b e stored in the binding
quote special form
of identi er
Remarks
Syntax
quote form
The value of form is stored in the top lexical binding of iden
quote object
ti er It is a static error to attempt to mo dify the binding
of a de ned constant
Arguments
nil null
object the object to b e quoted
Remarks
The symbol nil is de ned to b e immutably b ound to the
Result
empty list which is represented as The empty list is
The result is object used to denote the abstract b o olean value false
Programming Language EuLisp version
Remarks
defmacro form
The result of pro cessing the expression quote object is
defmacro macro name lambda list
object The object canbeany ob ject having an external
form
representation The sp ecial form quote can b e abbreviated
using apostrophe graphic representation so that quote
a can b e written a These two notations are used to incor
p orate literal constants in programs It is an error to mo dify
a literal expression
Arguments
macro name A symb ol naming an immutable top
Functions creation de nition and appli
lexical binding to b e initiali zed with a function having the
cation
sp eci ed lambda list and body
lambda list The parameter list of the function conform
lambda special form
ing to the syntax sp eci ed under lambda
Syntax
body A sequence of forms
lambda form
lambda lambda list form
Remarks
lambda list
The defmacro form de nes a function named by macro name
identifier A
and stores the de nition as the top lexical binding of macro
simple list
name The interpretation of the lambda list is as de ned for
rest list
lambda see Table
simple list
identifier A
NOTE A macro is automatically exp orted from the the mo dule
rest list
which de nes it A macro cannot b e used in the mo dule which
identifier identifier
de nes it
See also lambda
Arguments
lambda list The parameter list of the function conform
ing to the syntax sp eci ed in Table
defun syntax
form An expression
Syntax
Result
A function with the sp eci ed lambda list and sequence of
defun form
form s
simple defun
setter defun
simple defun
Remarks
defun function name lambda list
The function construction op erator is lambda Access to the
form
setter defun
lexical environment of de nition is guaranteed The syntax
defun
of lambda list is de ned by the grammar in Table
setter function name
lambda list form
If lambda list is an identi er it is b ound to a newly allo cated
list of the actual parameters This binding has lexical scop e
and inde nite extent If lambda list is a simple list the argu
ments are b ound to the corresp onding identi ers Otherwise
lambda list must b e a rest list In this case each identi er
Arguments
preceding the dot is b ound to the corresp onding argument
and the identi er succeeding the dot is b ound to a newly
function name A symb ol naming an immutable top
allo cated list whose elements are the remaining arguments
lexical binding to b e initiali zed with a function having the
These bindings have lexical scop e and inde nite extent It is
sp eci ed lambda list and body
a static error if the same identi er app ears more than once
in a lambda list It is an error to mo dify rest list
setter function name An expression denoting the
setter function to corresp ond to function name
defmacro syntax
lambda list The parameter list of the function conform
ing to the syntax sp eci ed under lambda
body A sequence of forms
Syntax
Programming Language EuLisp version
operand list list The op erands prepared for the op er Remarks
ator
The defun form de nes a function named by function name
and stores the de nition i as the top lexical binding of
function name or ii as the setter function of function name
Remarks
The interpretation of the lambda list is as de ned for lambda
Signalled by function call if the op erator is not an instance
The rewrite rules for defun are given b elow
of function
apply function
defun identi er defconstant identi er
lambda list lambda lambda list body
body
defun setter setter identi er
Syntax
setter identi er lambda lambda list body
lambda list body
apply form
apply function form
function call syntax
Arguments
Syntax
function An expression whichmust evaluate to an in
stance of function
function call form
form form A sequence of expressions which will
n
operator operand
be evaluated according to the rules given in function cal l
form An expression whichmust evaluate to a prop er
n
list It is an error if obj is not a prop er list
n
Arguments
operator This may b e a symb ol b eing either the name
Result
of a sp ecial form or a lexical variable or a function call
The result is the result of calling function with the actual
whichmust result in an instance of function
parameter list created by app ending form to a list of the
n
arguments form through form An error is signalled
An error is signalled condition class
n
condition class invalid operator if the rst argument
invalid operator if the op erator is not a function
is not an instance of function
operand Each operand must b e either an atomic ex
pression a literal expression or a function call
See also function cal l invalid operator
Result
Destructive Op erations
The result is the value of the application of operator to the
evaluation of operand
An assignment op eration mo di es the contents of a binding
named by a identi er that is a variable
Remarks
The operand expressions are evaluated in order from left to
setq special form
right The operator expression maybeevaluated at any time
b efore during or after the evaluation of the op erands
NOTE The ab ove rule for the evaluation of function calls was
Syntax
nally agreed up on for this version since it is in line with one
strand of common practice but it may b e revised in a future
version
setq form
setq identifier form
See also constant symbol quote
Arguments
invalid operator execution condition
identi er The identi er whose lexical binding is to b e
up dated
Initializ atio n Options
form An expression whose value is to b e stored in the
invalid operator object The ob ject whichwas b eing
binding of identi er
used as an op erator
Programming Language EuLisp version
Remarks Result
The result is the value of form
Signalled by setter setter if the up dater of the given
accessor is immutable
Remarks
The form is evaluated and the result is stored in the closest
See also setter
lexical binding named by identi er It is a static error to
mo dify an immutable binding
Conditional Expressions
setter function
if special form
Arguments
Syntax
reader An expression whichmust evaluate to an in
stance of function
if form
if antecedent consequent
Result
alternative
The writer corresp onding to reader
Remarks
Arguments
A generalized place up date facilityisprovided by setter
Given reader setter returns the corresp onding up date func
antecedent A form
tion If no suchfunctionisknown to setter an error is sig
nalled condition class no setter Thus setter car
consequent A form
returns the function to up date the car of a pair New up
date functions can b e added by using setter s up date func
tion which is accessed by the expression setter setter
alternative A form
Thus setter setter a reader a writer installs the
function whichisthevalue of a writer as the writer of
the reader function whichisthevalue of a reader All
Result
writer functions in this de nition and user de ned writers
have the same immutable status as other standard functions
Either the value of consequence or alternative dep ending on
such that attempting to rede ne such a function for exam
the value of antecedent
ple setter setter car a new value signals an error
condition class cannot update setter
Remarks
See also defgeneric defmethod defstruct
The antecedent is evaluated If the result is true the conse
defun
quence is evaluated otherwise the alternative is evaluated
Both consequence and alternative must b e sp eci ed The
result of if is the result of the evaluation of whichever of
consequence or alternative is chosen
no setter execution condition
Initializatio n Options
cond macro
object object The ob ject given to setter
Remarks
Syntax
Signalled by setter if there is no up dater for the given func
tion
cond macro
cond
antecedent consequent
cannot update setter execution condition
Initializatio n Options
Remarks
accessor object The given accessor ob ject
The cond macro provides a convenient syntax for collections
of if then elseif else expressions The rewrite rules for cond
updater object The given up dater ob ject
are given b elow
Programming Language EuLisp version
cond or
cond antecedent or antecedent cond or form form
cond or antecedent or form form let x form
antecedent cond if x
antecedent form antecedent form x
or form
cond if antecedent
antecedent form progn form
antecedent form cond
antecedent form
Variable Binding and Sequences
let cc special form
and macro
Syntax
Syntax
let cc form
let cc identifier form
and macro
and form
Arguments
identi er To b e b ound to the continuation of the let cc
Remarks
form
The expansion of an and form leads to the evaluation of the
sequence of forms from left to right The rst form in the
body A sequence of forms
sequence that evaluates to stops evaluation and none of
the forms to its right will b e evaluated that is to say itis
non strict The result of and is If none of the forms
Result
evaluate to the value of the last form is returned The
The result of evaluating the last form in body or the value of
rewrite rules for and are given b elow
the argumentgiven to the continuation b ound to identi er
Remarks
and t
and form form
The identi er is b ound to a new lo cation which is initial
and form form if form
ized with the continuation of the let cc form This binding
and form
is immutable and has lexical scop e and inde nite extent
Each form in body is evaluated in order in the environment
extended by the ab ove binding It is an error to call the
continuation outside the dynamic extentofthelet cc form
that created it The continuation is a function of one argu
ment Calling the continuation causes the restoration of the
or macro
lexical environment and dynamic environment that existed
b efore entering the let cc form
Syntax
Examples
An example of the use of let cc is given in Figure The
or macro
function path open takes a list of paths the name of a le
or form
and list of options to pass to open It tries to op en the le
by app ending the name to each path in turn Eachtime
as not found open fails it signals a condition that the le w
which is trapp ed by the handler function That calls the
Remarks
continuation b ound to fail to cause it to try the next path in
the list When open do es nd a le the continuation b ound
The expansion of an or form leads to the evaluation of the
to succeed is called with the stream as its argument which sequence of forms from left to right The value of the rst
is subsequently returned to the caller of path open If the
form that evaluates to true is the result of the or form and
path list is exhausted map section A terminates and an none of the forms to its right will b e evaluated that is to
error condition class cannot open path is signalled
say it is non strict If none of the forms evaluate to true
the value of the last form is returned The rewrite rules for
or are given b elow Note that x do es not o ccur free in any
See also block return from of form form
n
Programming Language EuLisp version
defun path open pathlist name options
Remarks
let cc succeed
In return from the identi er names the continuation of the
map
lexical block from which to return return from is the
lambda path
invo cation of the continuation of the blo ck named by identi
let cc fail
with handler
er The form is evaluated and the value is returned as the
lambda condition resume fail
value of the blo ck named by identi er The rewrite rules for
succeed apply open
return from are given b elow
format nil a a path name
options
pathlist
error
return from identi er identi er
format nil
return from identi er form
path open cannot open stream for a a
identi er form
pathlist name
cannot open path
Figure Example using let cc
See also block
labels special form
block macro
Syntax
Syntax
labels form
labels
block macro
function definition
block identifier form
form
function definition
identifier lambda list form
Remarks
The blo ck expression is used to establish a statically scop ed
Arguments
binding of an escap e function The blo ck variable is b ound
to the continuation of the blo ck The continuation can b e
identi er A symb ol naming a new inner lexical binding
invoked anywhere within the blo ckby using return from
to b e initial ized with the function having the lambda list The forms are evaluated in sequence and the value of the
and body sp eci ed
last one is returned as the value of the blo ck form See also
let cc The rewrite rules for block are given b elow
lambda list The parameter list of the function conform
The rewrite for block do es not preventtheblock b eing ex
ing to the syntax sp eci ed b elow
ited from anywhere in its dynamic extent since the function
b ound to identi er is a rst class item and can b e passed as
body A sequence of forms
an argument like other values
labels body A sequence of forms
block identi er
Result
block identi er form let cc identi er form
The labels op erator provides for lo cal mutually recursive
function creation Each identi er is b ound to a new inner
lexical binding initiali zed with the function constructed from
lambda list and body The scop e of the identi ers is the entire
See also return from
labels form The lambda list is either a single variable or
a list of variables see lambda Each form in labels body is
evaluated in order in the lexical environment extended with
the bindings of the identi ers The result of evaluating the
return from macro
last form in labels body is returned as the result of the labels
form
Syntax
let macro
return from macro
return from identifier form
Syntax
Programming Language EuLisp version
let form progn form
let macro
let var form let var form
let identifier binding
var form let var form
form
var var
binding
identifier
form form
identifier form
Remarks
progn special form
The optional identi er denotes that the let form can b e
called from within its body This is an abbreviation for
labels form in which identi er is b ound to a function whose
Syntax
parameters are the identi ers of the binding s of the let
whose b o dy is that of the let and whose initial call passes
the values of the initiali zin g form of the binding s A bind
progn form
ing is sp eci ed by either an identi eroratwo element list
progn form
of an identi er and an initiali zi ng form All the initializi ng
forms are evaluated in order from left to right in the current
environment and the variables named by the identi ers in
the bindings are b ound to new lo cations holding the results
Arguments
Each form in body is evaluated in order in the environment
extended by the ab ove bindings The result of evaluating the
form A sequence of forms and in certain circum
last form in body is returned as the result of the let form
stances de ning forms
The rewrite rules for let are given b elow
let form progn form
Result
let id form lambda id id id
The sequence of formsisevaluated from left to right return
id form form
ing the value of the last one as the result of the progn form
id form form
If the sequence of forms is empty progn returns
form
let id labels
id form id id id
Remarks
id form
id form
If the progn form o ccurs enclosed only by progn forms and
form
a defmodule form then the forms within the progn can b e
de ning forms since they app ear in the top lexical environ
ment It is a static error for de ning forms to app ear in
inner lexical environments
let macro
unwind protect special form
Syntax
Syntax
let star macro
let binding form
unwind protect form
unwind protect protected form
after form
Remarks
Arguments
A binding is sp eci ed byatwo elementlistofavariable and
an initiali zin g form The rst initiali zin g form is evaluated
in the currentenvironment and the corresp onding variable is
protected form A form
b ound to a new lo cation containing that result Subsequent
bindings are pro cessed in turn evaluating the initializi ng
after form A sequence of forms
form in the environment extended by the previous binding
Each form in body is evaluated in order in the environment
extended by the ab ove bindings The result of evaluating
Result
the last form is returned as the result of the let form The
The value of protected form rewrite rules for let are given b elow
Programming Language EuLisp version
progn
Remarks
let cc k
wait provides a generic interface to op erations whichmay
labels
blo ck Execution of the current thread will continue b eyond
loop
the wait form only when one of the following happ ened
let cc k unwind protect k k
continuation bound to k
loop
a A condition asso ciated with obj returns true
loop
continuation bound to k
b timeout time units elapse
c A condition is raised by another thread on this thread
Figure Interaction of unwind protect with non
lo cal exits
wait returns if timeout o ccurs else it returns a non nil
value
A timeout argumentof or zero denotes a p olling op era
Remarks
tion A timeout argumentoft denotes inde nite blo cking
cases a or c ab ove A timeout argument
The normal action of unwind protect is to pro cess protected
of a non negativeinteger denotes the minimum number of
form and then eachofafter forms in order returning the
time units b efore timeout The numb er of time units in
value of protected form as the result of unwind protect A
a second is given by the implementation de n ed constant
non lo cal exit from the dynamic extentofprotected form
ticks per second
which can b e caused by pro cessing a non lo cal exit form
will cause eachofafter forms to b e pro cessed b efore con
trol go es to the continuation sp eci ed in the non lo cal exit
Examples
form The after forms are not protected in anywayby the
This co de fragmentcopiescharacters from stream s to the
current unwind protect Should any kind of non lo cal exit
current output stream until no data is received on the stream
o ccur during the pro cessing of the after forms the after
for a p erio d of at least second
forms b eing pro cessed are not reentered Instead control is
transferred to wherever sp eci ed by the new non lo cal exit
but the after form sofanyintervening unwind protectsbe
labels
loop tween the dynamic extent of the target of control transfer
when wait s round ticks per second
and the current unwind protect are evaluated in increasing
print read char s
order of dynamic extent
loop
loop
Examples
See also threads section streams sec
The co de fragment in Figure illustrates b oth the use of
tion A
unwind protect and of a di erence b etween the semantics
of EULISP and some other Lisps Stepping through the eval
uation of this form k is b ound to the continuation of its
ticks per second double float
let cc form a recursive function named loop is constructed
loop is called from the b o dy of the labels form k is b ound
to the continuation of its let cc form unwind protect calls
The numb er of time units in a second expressed as a
k the after forms of unwind protect are evaluated in or
double precision oating p ointnumber This value is
der k is called loop is called etc This program lo ops
implementation de ned
inde nitely
Quasiquotation Expressions
Events
quasiquote macro
The de ned name of this mo dule is event
wait generic function
Syntax
Generic Arguments
quasiquote macro
quasiquote skeleton
obj An ob ject
timeout object One of t or a non negative in
teger Remarks
Quasiquotation is also known as backquoting A
quasiquoted expression is a convenientwayofbuildinga
Result
structure The skeleton describ es the shap e and generally
Returns if timeout was reached otherwise a non value manyoftheentries in the structure but some holes remain
Programming Language EuLisp version
Syntax of Level de ning forms to b e lled The quasiquote macro can b e abbreviated by
using the glyph called grave accent so that quasiquote
expression can b e written expression
module
defmodule module name
module directives module form
module name
unquote syntax
identifier A
module directives
module directive
module directive
Syntax
export identifier
expose module descriptor
import module descriptor
unquote syntax
syntax module descriptor
unquote form
level module form
form
export identifier
level expression
defining form
progn module form
Remarks
module descriptor
module name
See unquote splicing
module filter
module filter
except identifier
unquote splicing syntax
module descriptor
only identifier
module descriptor
rename rename pair
Syntax
module descriptor
rename pair
identifier identifier
unquotespliceing syntax
unquote splicing form
form
defstruct form
defstruct class name superclass name
slot description list class option
class name
Remarks
identifier A
The holes in a quasiquoted expression are identi ed by un
superclass name
quote expressions of which there are two kinds forms whose
identifier A
slot description list
value is to b e inserted at that lo cation in the structure and
slot decsription
forms whose value is to b e spliced into the structure at that
slot description
lo cation The former is indicated byan unquote expres
slot name
sion and the latter byanunquote splicing expression In
slot name slot option
unquote splice the form must result in a prop er list The
slot name
insertion of the result of an unquote splice expression is as if
identifier A
the op ening and closing parentheses of the list are removed
slot option
and all the elements of the list are app ended in place of the
initarg identifier A
unquote splice expression
initform level expression
reader identifier A
writer identifier A
The syntax forms unquote and unquote splicing can b e
accessor identifier A
abbreviated resp ectively by using the glyph called comma
class option
preceding an expression and by using the diphthong
initargs identifier
comma followed by the glyph called commercial at pre
constructor identifier
ceding a form Thus unquote a maybewritten a and
initarg name
unquote splicinga can b e written a
predicate identifier A
Examples
a list b a b
a list b a b
Summary of Level Expressions and Def
initions
This section gives the syntax of all lev el expressions and
de nitions together The syntax of data ob jects is given
in the section p ertaining to the class and is summarized in
section A
Programming Language EuLisp version
defgeneric form lambda form
defgeneric gf name gf lambda list lambda lambda list form
level init option lambda list
gf name identifier A
identifier A simple list
gf lambda list rest list
specialized lambda list simple list
level init option identifier A
method method description rest list
identifier method description identifier
specialized lambda list form
specialized lambda list
specialized parameter
function call form
specialized parameter
operator operand
identifier A
specialized parameter
identifier class name A
quote form
identifier A
quote object
defmethod form
setq form
defmethod gf locator
setq identifier form
specialized lambda list
form
gf locator
identifier
if form
setter identifier
if antecedent consequent
converter identifier
alternative
defconstant form
let cc form
defconstant identifier form
let cc identifier form
deflocal form
labels form
deflocal identifier form
labels
function definition
form
function definition
defmacro form
identifier lambda list form
defmacro macro name lambda list
form
progn form
progn form
defun form
simple defun
setter defun
simple defun
unwind protect form
defun function name lambda list
unwind protect protected form
form
after form
setter defun
defun
setter function name
apply form
lambda list form
apply function form
Syntax of Level expressions
Syntax of Level macros
generic lambda form
cond macro
generic lambda gf lambda list
cond
level init option
antecedent consequent
and macro
and form
or macro
or form
Programming Language EuLisp version
block macro
block identifier form
return from macro
return from identifier form
let macro
let identifier binding
form
binding
identifier
identifier form
let star macro
let binding form
quasiquote macro
quasiquote skeleton
unquote syntax
unquote form
form
unquotespliceing syntax
unquote splicing form
form
Programming Language EuLisp version
Annex A
normative
Level Mo dule Library
Table A Character Syntax
A Characters
The de ned name of this mo dule is character
character token
literal character token
special character token
A character syntax
control character token
numeric character token
literal character token
Character literals are denoted by the extension glyph called
letter
hash followed by the character extension glyph called
decimal digit
reverse solidus followed by the name of the character
non alphabetic
The syntax for the external representation of characters is
control character token
de ned in Table A For most characters their name is the
letter
same as the glyph asso ciated with the character for example
special character token
alert
the character a has the name a and has the external
backspace
representation a Certain characters in the group named
delete
special see Table and also Table havesymb olic names
formfeed
for example the newline character has the name new line and
linefeed
has the external representation newline These sp ecial
newline
cases are the characters in the pro duction special character
return
token in Table A
tab
space
Anycharacter whichdoesnothave a name and therebyan
vertical tab
numeric character token
external representation dealt with by cases describ ed so far
x hex digit
is represented by x followed by up to four hexadecimal
x hex digit hex digit
digits The value of the hexadecimal numb er represents the
x hex digit hex digit hex digit
p osition of the character in the currentcharacter set Exam
x hex digit hex digit hex digit
ples of suchcharacter literals are x and xabcd which
hex digit
denote resp ectively the characters at p osition and at p o
sition in the character set current at the time of read
ing or writing The syntax for the external representation of
characters is de ned in Table A
character character Acharacter
NOTE This text refers to the currentcharacter set but de
nes no means of selecting alternativecharacter sets This is to
allow for future extensions and implementation de ned extensions
A Result
which supp ort more than one character set
If character is the same character as character the result
is character otherwise the result is
A character class
A binary method
The class of all characters
A Sp ecialized Arguments
A characterp function
character character Acharacter
A Arguments
character character Acharacter
object Ob ject to examine
A Result
A Result
If b oth characters denote upp ercase alphab etic or b oth de
Returns object if it is a character otherwise
note lowercase alphab etic the result is de ned by alpha
b etical order If b oth characters denote a digit the result
is de ned bynumerical order In these three cases if the
comparison is true the result is character otherwise it is
A equal method
Any other comparison is an error and the result of such
comparisons is unde ned
A Sp ecialized Arguments
A Examples character character Acharacter
Programming Language EuLisp version
binary A Z A
A Result
binar a z a
If character denotes an lower case character a character de
binary
noting its upp er case counterpart is returned Otherwise the
binary A a unde ned
result is the argument
binary A unde ned
binary a unde ned
A generic prin method
A See also Metho d on binary A for strings
A
A Sp ecialized Arguments
character character Character to b e ouptut on
A as lowercase generic function
stream
stream stream Stream on which character is to b e
A Generic Arguments
ouptut
object object An ob ject to convert to lower case
A Result
A Result
The character character
An instance of the same class as object converted to lower
case according to the actions of the appropriate metho d for
A Remarks
the class of object
Output the interpretation of character on stream
A
See also Another metho d is de ned on as lowercase for
A generic write method
strings A
A Sp ecialized Arguments
A as lowercase method
character character Character to b e ouptut on
stream
A Sp ecialized Arguments
stream stream Stream on which character is to b e
character character Acharacter
ouptut
A Result
A Result
If character denotes an upp er case character a character
The character character
denoting its lower case counterpart is returned Otherwise
the result is the argument
A Remarks
Output external representation of character on stream in the
A as uppercase generic function
format name as describ ed at the b eginning of this section
A Generic Arguments
object object An ob ject to convert to upp er case
A Result
An instance of the same class as object converted to upp er
case according to the actions of the appropriate metho d for
the class of object
A
See also Another metho d is de ned on as uppercase for
strings A
A as uppercase method
A Sp ecialized Arguments
character character Acharacter
Programming Language EuLisp version
The result is the result of the applicatio n of function to A Collections
the accumulated result and successive elements of col lection
The initial value of the accumulated result is supplied by obj
The de ned name of this mo dule is collection Acol lec
tion is de ned as an instance of one of list string
vector table or any user de ned class for whicha
A Examples
metho d is added to any of the collection manipulati on func
Note that the order of the elements in the result of the second
tions Collection do es not name a class and do es not form a
example dep ends on the hashing algorithm of the implemen
part of the class hierarchy This mo dule de nes a set of op er
tation and do es not prescrib e the result that any particular
ators on collections as generic functions and default metho ds
implementation must give
with the b ehaviours given here
accumulate
When iterating over a single collection the order in whichel
accumulate c b a
ements are pro cessed might not b e imp ortant but as so on as
lambda a v cons v a
more than one collection is involved it is necessary to sp ec
ify how the collections are aligned so that it is clear which
make table
elements of the collections will b e pro cessed together This
entries
is quite straightforward in the cases of list string
b a c
and vector since there is an intuitive natural order for
the elements which allows them to b e identi ed by a non
negativeinteger Thus when iterating over a combination
of any of these all the elements at index p osition i will b e
A accumulate generic function
pro cessed together starting with the elements at p osition
and nishing with those at p osition n where n is the
A Generic Arguments
size of the smallest collection in the combination The sub
set of collections whichhave natural order is called sequence
function function A function of two arguments
ti ed by the predicate and memb ers of this set can b e iden
sequencep while collections in general can b e identi ed by
col lection object The collection which is the sub
collectionp
ject of the accumulation op eration
Collection alignment is more complicated when tables are in
volved since they use explicit keys rather than natural order
A Result
to identify their elements In any iteration over a combina
The result is the result of the applicatio n of function to
tion of collections including a table or some tables the set
the accumulated result and successive elements of col lection
of keys used is the intersection of the keys of the tables and
starting with the second element The initial value of the ac
the implicit keys of the other collection classes present this
cumulated result is the rst elementofcol lection The terms
identi es the elements of the collections with common keys
rst and second corresp ond to the appropriate elements of
Thus for an iteration to pro cess any elements from the com
a natural order collection but no elements in particular of
bination of a collection with natural order and a table the
an explicit key collection If col lection is empty the result is
table must havesomeinteger keys and they must b e in the
range siz e of the collection with natural order
A conforming level implementation must de ne metho ds
A Examples
on these functions to supp ort op erations on lists A
accumulate
strings A tables A vector A and any com
lambda a v
bination of these
if evenp v cons v a a
A collection condition condition
A anyp generic function
This is the condition class for all collection pro cessing con
ditions
A Generic Arguments
function function A function to b e used as a pred
A accumulate generic function
icate on the elements of the collection s
col lection object A collection
A Generic Arguments
more col lections More collections
function function A function of two arguments
obj object The ob ject which is the initial value for
A Result
the accumulation op eration
The function is applied to argument lists constructed from
corresp onding successive elements of col lection and more
col lection object The collection which is the sub
col lections If the result is true the result of anyp is true
ject of the accumulation op eration
and there are no further applications of function to elements
of col lection and more col lections Ifany of the collections
is exhausted the result of any is A Result
Programming Language EuLisp version
A Examples
A do generic function
anyp even true
anyp true
lambda a b a b
A Generic Arguments
function function A function
A collectionp generic function
col lection object A collection
more col lections More collections
A Generic Arguments
A Result
object object An ob ject to examine
The result is This op erator is used for side e ect only
The function is applied to argument lists constructed from
A Result
corresp onding successive elements of col lection and more
col lections and the result is discarded Application stops if
Returns true if object is a collection otherwise
any of the collections is exhausted
A Remarks
A Examples
This predicate do es not return object b ecause is a collec
do prin b c bc
tion
do write b c b c
A concatenate generic function
A element generic function
A Generic Arguments
A Generic Arguments
col lection object A collection
col lection object The ob ject to b e accessed or up
dated
more col lections More collections
key object The ob ject identifying the key of the
elementincol lection
A Result
The result is an ob ject of the same class as col lection
A Result
The value asso ciated with key in col lection
A Remarks
The contents of the result ob ject dep end on whether col lec
tion has natural order or not
A Examples
element abc b
a If col lection has natural order then the size of the
element a b c b
result is the sum of the sizes of col lection and more
element a b c b
col lections The result collection is initiali zed with the
element b
elements of col lection followed by the elements of eachof
make table fill value b
more col lections taken in turn If any element cannot b e
stored in the result collection for example if the result is
a string and some elementisnotacharacter an error is
signalled condition class collection condition
A setter element setter
b If col lection do es not have natural order then the
result will contain asso ciations for eachofthekeys in col
A Generic Arguments
lection and more col lections Ifanykey o ccurs more than
once the asso ciated value in the result is the value of the
col lection object The ob ject to b e accessed or up
last o ccurrence of that key after pro cessing col lection and
dated
eachofmore col lections taken in turn
key object The ob ject identifying the key of the
elementincol lection
A Examples
concatenate bc b c value object The ob ject to replace the value asso
concatenate a b ab ciated with key in col lection for setter
concatenate
table
make table
c
A Result
a b
b
The argument supplied as value having up dated the asso ci
c
ation of key in col lection to refer to value
Programming Language EuLisp version
A Result
The result is an ob ject of the same class as col lection The A emptyp generic function
elements of the result are computed by the application of
function to argument lists constructed from corresp onding
A Generic Arguments
successive elements of col lection and more col lections Ap
plication stops if any of the collections is exhausted
col lection object The ob ject to b e examined
A Examples
A Result
map cons
Returns true if col lection is the ob ject identi ed with the
map
empty ob ject for that class of collection
lambda f f
A Examples
emptyp true
A member generic function
emptyp true
emptyp true
emptyp make table true
A Generic Arguments
object object The ob ject to b e searched for in col
lection
A fill generic function
col lection object The collection to b e searched
A Generic Arguments
test function The function to b e used to com
pare object and the elements of col lection
col lection object A collection to b e partially
lled
A Result
object object The ob ject with which to ll col lec
Returns true if there is an elementofcol lection such that the
tion
result of the application of test to object and that element
is true If test is not supplied eql is used by default Note
keys The keys with which object is to b e asso ciated
that true denotes anyvalue that is not and that the class
of the result dep ends on the class of col lection In particular
if col lection is a list the result of member is a list
A Result
The result is
A Examples
member b abc true
A Remarks
member b a b c b c
This function side e ects col lection by up dating the values
member b a b c true
asso ciated with each of the sp eci ed keys with obj Ifnokeys
member true
are sp eci ed the whole collection is lled with obj Other
b
wise the key sp eci cation can taketwo forms
make table
entries
a A collection in which case the values of the collection
b a c
are taken to b e the keys of col lection to b e asso ciated with
obj
A reverse generic function
b Two xed precision integers denoting the start and
end keys resp ectively in a natural order collection to b e
asso ciated with obj An error is signalled condition class
A Generic Arguments
collection condition if col lection do es not have natu
ral order It is an error if the start and end do not sp ecify
col lection object A collection
al of the interval siz e where an ascending sub interv
size is that of col lection
A Result
The result is an ob ject of the same class as col lection whose
A map generic function
elements are the same as those in col lection but in the re
verse order with resp ect to the natural order of col lection If
col lection do es not have natural order the result is equal to
A Generic Arguments
the argument
function function A function
A Examples
col lection object A collection
reverse abc cba
reverse
more col lections More collections
reverse a b c c b a
Programming Language EuLisp version
A sequencep generic function A converter string method
A Sp ecialized Arguments
A Generic Arguments
col lection object A collection to b e converted into
object object An ob ject to examine
a string
A Result
A Result
Returns true if object is a sequence has natural order oth
If col lection is a string the result is the argument Other
erwise
wise a string is constructed and returned whose elements are
the elements of col lection as long as al l the elements of col
lection are characters An error is signalled condition class
A Remarks
conversion condition ifany elementofcol lection is not a
This predicate do es not return object b ecause is a se
character If col lection has natural order then the elements
quence
will app ear in the result in the same order as in col lection
If col lection do es not have natural order the order in the
resulting string is unde ned
A size generic function
A See also Conversion A
A Generic Arguments
A converter table method
col lection object The ob ject to b e examined
A Sp ecialized Arguments
A Result
col lection object A collection to b e converted into
An integer which denotes the size of col lection according to
a table
the metho d for the class of col lection
A Result
A Examples
If col lection is a table the result is the argument Other
size
wise a table is constructed and returned whose elements are
size
the elements of col lection Ifcol lection has natural order
size
then the elements will b e stored under integer keys in the
size make table
range size otherwise the keys used will b e the keys
size abc
asso ciated with the elements of col lection
size cons
size cons
size cons cons
A See also Conversion A
size
size a b c
size make table entries a
A converter vector method
A Sp ecialized Arguments
A converter list method
col lection object A collection to b e converted into
A Sp ecialized Arguments
avector
col lection object A collection to b e converted into
A Result
a list
If col lection is a vector the result is the argument Otherwise
avector is constructed and returned whose elements are the
elements of col lection Ifcol lection has natural order then
A Result
the elements will app ear in the result in the same order as
If col lection is a list the result is the argument Otherwise
in col lection Ifcol lection do es not have natural order the
a list is constructed and returned whose elements are the
order in the resulting vector is unde ned
elements of col lection Ifcol lection has natural order then
the elements will app ear in the result in the same order as
in col lection Ifcol lection do es not have natural order the
A See also Conversion A
order in the resulting list is unde ned
A See also Conversion A
Programming Language EuLisp version
A Result A Comparison
If the class of object and of object is the same and is a
The de ned name of this mo dule is compare There are four
sub class of number the result is that of comparing them
functions for comparing ob jects for equality of which is
under If the class of object and of object is the same and
sp eci cally for comparing numeric values and eq eql and
is a sub class of character the result is that of comparing
equal are for all ob jects The latter three are related in the
them under equal Otherwise the result is that of comparing
following way
them under eq
eq ab eql ab equal ab
eq ab eql ab equal ab
A Examples
Given the same set of examples as for eq the same result is
There is one function for comparing ob jects by order which
obtained except in the following cases
is called and which is implemented by the generic function
binary A summary of the comparison functions and the
eql t
classes for which they have de ned b ehaviour is given in
eql t
Table A
eql a a t
A eq function
A equal generic function
A Arguments
A Arguments
object An ob ject
object An ob ject
object An ob ject
object An ob ject
A Result
A Result
Compares object and object and returns t if they are the
Returns true or false according to the metho d for the
same ob ject otherwise Same in this context means
class es of object and object It is an error if either or
identi es the same memory lo cation
b oth of the arguments is self referential
A Remarks
A See also Class sp eci c metho ds on equal are de
In the case of numb ers and characters the b ehaviour of eq
ned for characters A lists A numb ers A
might di er b etween pro cessors b ecause of implementation
strings A and vectors A All other cases are han
choices ab out internal representations Therefore eq might
dled by the default metho d
return t or for numb ers which are and similarly for
characters which are eql dep ending on the implementation
A equal method
A Examples
eq a a t
A Sp ecialized Arguments
eq a b
eq t or
object object An ob ject
eq
eq t or
object object An ob ject
eq cons a b cons a c
eq cons a b cons a b
or eq a b a b t
A Result
let x cons a b eq x x t
The result is as if eql had b een called with the arguments
let x a b eq x x t
supplied
eq a a t or
eq string string t or
eq a b a b t or
A Remarks
let x a b eq x x t
Note that in the case of this metho d b eing invoked from
equal the arguments cannot b e charactersornumbers
A eql function
A function
A Arguments
A Arguments
object An ob ject
object An ob ject number A non empty sequence of numbers
Programming Language EuLisp version
Table A Summary of comparison functions
eq object object
eql object object
character character equal
fixed precision integer fixed precision integer binary
double float double float binary
equal object object
character character
null null
number number eql
cons cons
string string
vector vector
number number binary
binary fixed precision integer fixed precision integer
double float double float
object object binary
binary character character
fixed precision integer fixed precision integer
double float double float
string string
A Result
A binary generic function
Given one argument the result is true Given more than one
argument the result is determined by binary returning true
if all the arguments are the same otherwise
A Generic Arguments
object object An ob ject
A binary generic function
object object An ob ject
A Generic Arguments
A Result
number number Anumb er
The rst argument if it is less than the second according to
number number Anumb er
the metho d for the class of the arguments otherwise
A Result
A See also Class sp eci c metho ds on binary are
One of the arguments or
de ned for characters A strings A xed precision
integers A and double oats A
A Remarks
The result is either a number or This is determined by
A max function
whichever class sp eci c metho d is most applicabl e for the
supplied arguments
A Arguments
A See also Class sp eci c metho ds on binary are de
object A non empty sequence of ob jects
ned for xed precision integer A and double oat A
A Result
A function
The maximal element of the sequence of ob jects object up to
object using the generic function binary Zeroarguments
n
A Arguments
is an error One argument returns object
object A non empty sequence of ob jects
A min function
A Result
Given one argument the result is true Given more than one
A Arguments
argument the result is true if the sequence of ob jects object
up to object is strictly increasing according to the generic
n
object A non empty sequence of ob jects
function binary Otherwise the result is
Programming Language EuLisp version
A Result A Conversion
The minimal element of the sequence of ob jects object up to
The de ned name of this mo dule is convert
object using the generic function binary Zero arguments
n
is an error One argument returns object
The mechanism for the conversion of an instance of one class
to an instance of another is de ned by a user extensible
framework which has some similarity to the setter mech
anism
To the user the interface to conversion is via the function
convert whichtakes an ob ject and some class to whichthe
ob ject is to b e converted The target class is used to access
an asso ciated converter function in fact a generic function
which is applied to the source instance dispatching on its
class to select the metho d which implements the appropriate
conversion Thus having de ned a new class to whichit
may b e desirable to convert instances of other classes the
programmer de nes a generic function
defgeneric converter new class instance
Hereafter new converter metho ds may b e de ned for new
class using a similar extended syntax for defmethod
defmethod converter new class
instance other class
The conversion is implemented by de ning metho ds on the
converter for new class which sp ecialize on the source class
This is also how metho ds are do cumented in this text by
an entry for a metho d on the converter function for the tar
get class In general the metho d for a given source class
is de ned in the section ab out that class for example con
verters from one kind of collection to another are de ned in
section A converters from string in section A etc
A convert function
A Arguments
object An instance of some class to b e converted to an
instance of class
class The class to which object is to b e converted
A Result
Returns an instance of class whichisequivalentinsome
class sp eci c sense to object whichmaybeaninstanceof
anytyp e Calls the converter function asso ciated with class
to carry out the conversion op eration An error is signalled
condition no converter if there is no asso ciated function
An error is signalled condition no applicable method if
there is no metho d to convert an instance of the class of
object to an instance of class
A conversion condition condition
This is the general condition class for all conditions arising
from conversion op erations
Programming Language EuLisp version
A Initializatio n Options A Copying
source object The ob ject to b e converted into an
The de ned name of this mo dule is copy
instance of target class
target class class The target class for the conver
A deep copy generic function
sion op eration
A Generic Arguments
A Remarks
Should b e signalled by convert oraconverter metho d
object An ob ject to b e copied
A converter function A Result
Constructs and returns a copy of the source which is the same
under some class sp eci c predicate as the source and whose
A Arguments
slots contain copies of the ob jects stored in the corresp onding
slots of the source and so on The exact b ehaviour for each
target class The class whose set of conversion metho ds
class of object is de ned by the most applicabl e metho d for
is required
object
A Result
A See also Class sp eci c sections which de ne meth
The accessor returns the converter function for the class
ods on deep copy list A string A table A
target class The converter is a generic function with meth
and vector A
o ds sp ecialized on the class of the ob ject to b e converted
A deep copy method
A setter converter setter
A Sp ecialized Arguments
A Arguments
object object An ob ject
target class The class whose converter function is to b e
replaced
A Result
generic function The new converter function
Returns object
A Result
The new converter function The setter function replaces
A deep copy method
the converter function for the class target class by generic
function The new converter function must b e an instance
of generic function
A Sp ecialized Arguments
struct structure class A structure
A Remarks
Converter metho ds from one class to another are de ned in
the section p ertaining to the source class
A Result
Constructs and returns a new structure whose slots are ini
tialized with copies using deep copy of the contents of the
A See also Converter metho ds are de ned for collec
slots of struct
tions double oat A xed precision integer A
string A symb ol A vector A
A shallow copy generic function
A Generic Arguments
object An ob ject to b e copied
A Result
Constructs and returns a copy of the source which is the
same under some class sp eci c predicate as the source The
exact b ehaviour for each class of object is de ned by the most
applicable metho d for object
Programming Language EuLisp version
A See also Class sp eci c sections which de ne meth A Double Precision Floats
ods on shallow copy pair A string A ta
ble A and vector A
The de ned name of this mo dule is double Arithmetic op
erations for double float are de ned by metho ds on the
generic functions de ned in the numb er mo dule A
A shallow copy method
binary binary binary binary binary binary
mod negate zerop
A Sp ecialized Arguments
the oat mo dule A
object object An ob ject
ceiling floor round truncate
A Result
and the elementary functions mo dule A
Returns object
acos asin atan atan cos sin tan cosh sinh tanh
exp log log pow sqrt
A shallow copy method
The b ehaviour of these functions is de ned in the mo dules
noted ab ove
A Sp ecialized Arguments
A double float class
struct structure class A structure
The class of all double precision oating p ointnumbers
A Result
Constructs and returns a new structure whose slots are ini
The syntax for the exp onent of a double precision oating
tialized with the contents of the correpsonding slots of struct
pointisgiven b elow The general syntax for oating p oint
numb ers is given in section A
double exponent
d D sign decimal integer A
A double float p function
A Arguments
object Ob ject to examine
A Result
Returns object if it is a double oat otherwise
A See also floatp A
A most positive double float double oat
A Remarks
The value of most positive double float is that p ositive
double precision oating p ointnumb er closest in value to
but not equal to p ositive in nity that the pro cessor pro
vides
A least positive double float double oat
A Remarks
The value of least positive double float is that p ositive
Programming Language EuLisp version
A Remarks double precision oating p ointnumb er closest in value to
but not equal to zero that the pro cessor provides
This function is the same as round It is de ned for the sake
of symmetry
A least negative double float double oat
A generic prin method
A Remarks
A Sp ecialized Arguments
The value of least negative double float is that negative
double precision oating p ointnumb er closest in value to
double double float The double oat to b e out
but not equal to zero that the pro cessor provides Even if
put on stream
the pro cessor provide negative zero this value must not b e
negative zero
stream stream The stream on which the represen
tation is to b e output
A most negative double float double oat
A Result
The double oat supplied as the rst argument
A Remarks
The value of most negative double float is that negative
A Remarks
double precision oating p ointnumb er closest in value to
Outputs the external representation of double on stream as
but not equal to negative in nity that the pro cessor pro
an optional sign preceding the syntax de ned by oat for
vides
mat Finer control over the format of the output of oating
p ointnumb ers is provided by some of the formatting sp eci
cations of format see section A
A equal method
A Sp ecialized Arguments
A generic write method
double double float A double precision oat
A Sp ecialized Arguments
double double float A double precision oat
double double float The double oat to b e out
put on stream
A Result
stream stream The stream on which the represen
The result of calling binary on double and double
tation is to b e output
A Result
A converter string method
The double oat supplied as the rst argument
A Sp ecialized Arguments
A Remarks
Outputs the external representation of double on stream as
x double float A double precision oat
an optional sign preceding the syntax de ned by oat for
mat Finer control over the format of the output of oating
p ointnumb ers is provided by some of the formatting sp eci
A Result
cations of format see section A
Constructs and returns a string the characters of which
corresp ond to the external representation of x as pro duced
by generic prin namely that sp eci ed in the syntax as
sign oat format
A converter fixed precision integer method
A Sp ecialized Arguments
x double float A double precision oat
A Result
A xed precision integer
Programming Language EuLisp version
oat float A oating p ointnumber A Elementary Functions
The de ned name of this mo dule is elementary functions
A Result
The functionality de ned for this mo dule is intentionally
precisely that of the trigonmetric functions hyp erb olic func
Computes the principal value of the arc tangent of
tions exp onential and logarithmic functions and p ower func
oat oat whichisavalue in the range radians
tions de ned for math h in ISO IEC with the
using the signs of b oth arguments to determine the quadrant
exceptions of frexp ldexp and modf
of the result An error might b e signalled condition cl ass
domain condition if either oat or oat is zero
A pi double oat
A cos generic function
A Remarks
A Generic Arguments
The value of pi is the ratio the circumference of a circle to its
diameter stored to double precision oating p oint accuracy
oat float A oating p ointnumb er
A acos generic function
A Result
Computes the cosine of oat measured in radians
A Generic Arguments
oat float A oating p ointnumb er
A sin generic function
A Result
A Generic Arguments
Computes the principal value of the arc cosine of oat which
oat float A oating p ointnumb er
is a value in the range radians An error is signalled
condition class domain condition if oat is not in the
range
A Result
Computes the sine of oat measured in radians
A asin generic function
A tan generic function
A Generic Arguments
A Generic Arguments
oat float A oating p ointnumb er
oat float A oating p ointnumb er
A Result
Computes the principal value of the arc sine of oat which
A Result
is a value in the range radians An error is
Computes the tangentof oat measured in radians
signalled condition clas s domain condition if oat is not
in the range
A cosh generic function
A atan generic function
A Generic Arguments
A Generic Arguments
oat float A oating p ointnumb er
oat float A oating p ointnumb er
A Result
A Result
Computes the hyp erb olic cosine of oat An error mightbe
signalled condition class range condition if the magni
Computes the principal value of the arc tangentof oat
tude of oat is to o large
which isavalue in the range radians
A sinh generic function
A atan generic function
A Generic Arguments
A Generic Arguments
oat float A oating p ointnumb er
oat float A oating p ointnumb er
Programming Language EuLisp version
oat float A oating p ointnumber A Result
Computes the hyp erb olic sine of oat An error might b e sig
oat float A oating p ointnumber
nalled condition class range condition if the magnitude
of oat is to o large
A Result
Computes oat raised to the p ower oat An error is sig
A tanh generic function
nalled condition class domain condition if oat is nega
tive and oat is not integral An error is signalled condition
class domain condition if the result cannot b e represented
A Generic Arguments
when oat is zero and oat is less than or equal to zero An
error might b e signalled condition class range condition
oat float A oating p ointnumber
if the result cannot b e represented
A Result
A sqrt generic function
Computes the hyp erb olic tangentof oat
A Generic Arguments
A exp generic function
oat float A oating p ointnumber
A Generic Arguments
A Result
oat float A oating p ointnumber
Computes the non negative square ro ot of oat An error
is signalled condition class domain condition if oat is
negative
A Result
Computes the exp onential function of oat An error might
b e signalled condition class range condition if the mag
nitude of oat is to o large
A log generic function
A Generic Arguments
oat float A oating p ointnumber
A Result
Computes the natural logarithm of oat An error is
signalled condition class domain condition if oat is
negative An error might b e signalled condition class
range condition if oat is zero
A log generic function
A Generic Arguments
oat float A oating p ointnumber
A Result
Computes the base ten logarithm of oat An error is
signalled condition class domain condition if oat is
negative An error might b e signalled condition class
range condition if oat is zero
A pow generic function
A Generic Arguments
Programming Language EuLisp version
A Result A Floating Point Numb ers
Returns object if it is a oating p ointnumb er otherwise
The de ned name of this mo dule is float This mo dule de
nes the abstract class float and the b ehaviour of some
generic functions on oating p ointnumbers Further op era
A ceiling generic function
tions on numb ers are de ned in the numb ers mo dule A
and further op erations on oating p ointnumb ers are de ned
in the elementary functions mo dule A A concrete oat
A Generic Arguments
class is de ned in the double oat mo dule A
oat float A oating p ointnumb er
A float syntax
A Result
Returns the smallest integral value not less than oat ex
pressed as a oat of the same class as the argument
The syntax for the external representation of oating p oint
literals is de ned in Table A The representation used by
write and prin is that of a sign a whole part and a fractional
part without an exp onent namely that de ned by oat for
A floor generic function
mat Finer control over the format of the output of oating
pointnumb ers is provided by some of the formatting sp eci
A Generic Arguments
cations of format section A
oat float A oating p ointnumb er
Table A Floating Point Syntax
A Result
float
Returns the largest integral value not greater than oat ex
sign unsigned float exponent
pressed as a oat of the same class as the argument
sign
unsigned float
float format
A round generic function
float format
float format
float format
A Arguments
decimal integer A
float format
oat A oating p ointnumber
decimal integer A
float format
float format decimal integer A
A Result
exponent
Returns the integer whose value is closest to oat except in
double exponent A
the case when oat is exactly half waybetween twointegers
when it is rounded to the one that is even
A oating p ointnumb er has six forms of external represen
tation dep ending on whether either or b oth the whole and
A truncate generic function
the fractional part are sp eci ed and on whether an exp onent
is sp eci ed In addition a p ositive oating p ointnumber
is optionally preceded by a plus sign and a negative oat
A Arguments
ing p ointnumb er is preceded byaminus sign For example
oat format oat format oat
oat A oating p ointnumber
format and with exp onents D D
D
A Result
Returns the greatest integer value whose magnitude is less
than or equal to oat
A float class
The abstract class which is the sup erclass of all oating p oint
numb ers
A floatp function
A Arguments
objext Ob ject to examine
Programming Language EuLisp version
integer fixed precision integer A xed preci A Fixed Precision Integers
sion integer
The de ned name of this mo dule is fpi Arithmetic op era
tions for fixed precision integer are de ned by meth
integer fixed precision integer A xed preci
o ds on the generic functions de ned in the numb er mo dule
sion integer
binary binary binary binary binary binary
binary binary gcd binary lcm mod negate zerop
A Result
The result of calling binary on integer and integer
and in the integer mo dule
evenp
A Remarks
The di erence b etween equal and is that the former only
The b ehaviour of these functions is de ned in the mo dules
compares numb ers of the same class whereas the latter co noted ab ove
erces the numb ers to b e of the same class b efore comparison
A fixed precision integer class
A converter string method
The class of all instances of xed precision integers
A Sp ecialized Arguments
A fpi class
integer fixed precision integer An integer
A Remarks
A Result
A constant binding whose value is
Constructs and returns a string the characters of whichcor
fixed precision integer
resp ond to the external representation of integer in decimal
notation
A fixed precision integer p function
A converter double float method
A Arguments
A Sp ecialized Arguments
object Ob ject to examine
integer fixed precision integer An integer
A Result
Returns object if it is xed precision integer otherwise
A Result
Returns a double oat whose value is the oating p ointap
proximation to integer
A most positive fixed precision integer
xed precision integer
A generic prin method
A Remarks
This is an implementation d e ned constant A conform
ing pro cessor must supp ort a value greater than or equal
A Sp ecialized Arguments
to and greater than or equal to the value of
maximum vector index
integer fixed precision integer An integer to
b e output on stream
A most negative fixed precision integer
stream stream The stream on which the represen
xed precision integer
tation is to b e output
A Remarks
A Result
This is an implementation de ned constant A conforming
The xed precision integer supplied as the rst argument
pro cessor must supp ort a value less than or equal to
A Remarks
A equal method
Outputs external representation of integer on stream in dec
imal as de ned by decimal integer at the b eginning of this
A Sp ecialized Arguments section
Programming Language EuLisp version
A Formatted IO
A generic write method
The de ned name of this mo dule is formatted io
A Sp ecialized Arguments
A scan function
integer fixed precision integer An integer to
b e output on stream
A Arguments
stream stream The stream on which the represen
format string A string containing format directives
tation is to b e output
stream A stream from which input is to b e taken
A Result
The xed precision integer supplied as the rst argument
A Result
Returns a list of the ob jects read from stream
A Remarks
Outputs external representation of integer on stream in dec
A Remarks
imal as de ned by decimal integer at the b eginning of this
section This function provides supp ort for formatted input The
format string sp eci es reading directives and inputs are
matched according to these directives An error is signaled
condition scan mismatch if the class of the ob ject read
is not compatible with the sp eci ed directive The second
optional argument sp eci es a stream from whichtotake
input If stream is not supplied input is taken from the re
sult of calling standard input stream Scan returns a list
of the ob jects read in
a any any ob ject
b binary an integer in binary format
c character a single character
d decimal an integer decimal format
n e a exp onential format oating p oint number
n f a xed format oating p oint number
o o ctal an integer in o ctal format
r radix an integer in sp eci ed radix format
x hexadecimal an integer in hexadecimal format
newline matches a newline character in the
input
A scan mismatch stream condition
A Initializati on Options
format string string The value of this option is the
format string that was passed to scan
input list The value of this option is a list of the items
read by scan up to and includi ng the ob ject that caused
the condition to b e signaled
A Remarks
This condition is signalled by scan if the format string do es
not match the data input from stream
Programming Language EuLisp version
nr radix the argumentmustbeaninteger and is
output in radix n notation Table A
A format function
s s expression uses write to output the argument
Table
A Arguments
n t tab output su cient spaces to reach the next
stream One of t or a stream
th
tab stop if n is not sp eci ed or the n tab stop if it is
format string A string containing format directives
x hexadecimal the argumentmustbeaninteger
and is output in hexadecimal notation Table A
object A sequence of ob jects to b e output on
stream
newline output a newline character using
newline
A Result
conditional newline output a newline char
Returns a list comprising those ob jects left in the sequence
acter using newline if it cannot b e determined that the
after the last format directivewas pro cessed
output stream is at the b eginning of a fresh line
tilde output a tilde character using prin
A Remarks
Has side e ect of outputting object s according the formats
sp eci ed in format string Ifstream is t the output is to
the current output stream If stream is a formatted
string is returned as the result of the call Otherwise stream
must b e a valid output stream Characters are output as
if the string were output by the prin function with the ex
ception of those pre xed by tilde graphic representation
which are treated sp ecially as detailed in the following
list These formatting directives are intentionally compat
ible with the facilities de ned for the function fprintf in
ISO IEC
a any uses prin to output the argument
b binary the argumentmust b e an integer and is
output in binary notation Table A
c character the argumentmust b e a character and
is output using write Table A
d decimal the argumentmustbeaninteger and is
output using write Table A
m n e exp onential format oating p oint the
argumentmust b e a oating p ointnumb er It is output in
the style d dddedd in a eld of width m characters
where there are n precision digits after the decimal p oint
or digits if n is not sp eci ed Table A If the value
to b e output has fewer characters than m it is padded on
the left with spaces
m n f xed format oating p oint the argu
mentmust b e a oating p ointnumb er It is output in the
style ddd ddd in a eld of width m characters where
the are n precision digits after the decimal p oint or dig
alue is rounded its if n is not sp eci ed Table A The v
to the appropriate numb er of digits If the value to b e
output has fewer characters than m it is padded on the
left with spaces
m n g generalized oating p oint the argument
must b e a oating p ointnumb er It is output in either
xed format or exp onential notation as appropriate Ta
ble A
o o ctal the argumentmust b e an integer and is
output in o ctal notation Table A
Programming Language EuLisp version
Table A Integer Syntax
A Integers
mo dule The de ned name of this mo dule is integer This
mo dule de nes the abstract class integer and the b e integer
sign unsigned integer
haviour of some generic functions on integers Further op era
sign
tions on numb ers are de ned in the numb ers mo dule A
A concrete integer class is de ned in the xed precision in
unsigned integer
teger mo dule A
binary integer
octal integer
decimal integer
hexadecimal integer
A integer syntax
specified base integer
binary integer
b binary digit binary digit
A p ositiveinteger is has its external representation as a se
binary digit
quence of digits optionally preceded by a plus sign A nega
tiveinteger is written as a sequence of digits preceded bya
octal integer
minus sign For example
o octal digit octal digit
octal digit
Integer literals have an external representation in any base
up to base For convenience base base and base decimal integer
decimal digit decimal digit
have distinguis hed notations b o and x resp ectively
hexadecimal integer
For example b o and x d all
x hexadecimal digit hexadecimal digit
denote the same value
hexadecimal digit
decimal digit
The general notation for an arbitrary base is base r where
hex lower letter
base is an unsigned decimal numb er Thus the ab ove ex
hex upper letter
amples may also b e written r r
hex lower letter
r r d or rya The reading of anynumber
a b c d e f
is terminated on encountering a character which cannot b e hex upper letter
A B C D E F
a constituent of that numb er The syntax for the external
specified base integer
representation of integer literals is de ned in Table A
base specification r
specified base digit
NOTE At present this text do es not de ne a class integer
specified base digit
with variable precision It is planned this should app ear in a fu
base specification
ture version at level of the language The class will b e named
decimal digit
variable precision integer The syntax given here is appli
decimal digit
cable to b oth xed and variable precision integers
specified base digit
decimal digit letter
A integer class
The abstract class which is the sup erclass of all integer num
b ers
A oddp function
A integerp function
A Arguments
integer An integer
A Arguments
object Ob ject to examine
A Result
Returns the equivalent of the logical negation of evenp ap
A Result
plied to integer
Returns object if it is an integer otherwise
A evenp generic function
A Arguments
integer integer An integer
A Result
Returns t if two divides integer otherwise
Programming Language EuLisp version
A Result A Lists
The empty list
The name of this mo dule is list The class list is an ab
stract class and has two sub classes null and cons The
only instance of null is the empty list The combination
A Remarks
of these two classes allows the creation of prop er lists since
Output the external representation of the empty list on
a prop er list is one whose last pair contains the empty list
stream as describ ed ab ove
in its cdr eld See also section A collections for further
op erations on lists
A pair syntax
A syntax
A pair is written as object object where object is called
A Remarks
the car and object is called the cdr There are two sp ecial
cases in the external representation of pair If object is the
The empty list which is the only instance of the class null
empty list then the pair is written as object Ifobject
has as its external representation an op en parenthesis fol
is an instance of pair then the pair is written as object
lowed by a close parenthesis The empty list is also used to
object object where object is the car of object and
denote the b o olean value false
object is the cdr with the ab ove rule for the emptylistap
plying By induction a list of length n is written as object
object object with the ab ove rule for the empty
n n
A null class
The representations of object and object list applying
are determined by the external representations de ned in
other sections of this de nition see character A
The class whose only instance is the empty list denoted
double float A fixed precision integer A
string A symbol A and vector A as
well as instances of cons itself The syntax for the external
A null function
representation of pairs and lists is de ned in Table A
A Arguments
Table A Pair and List Syntax
object Ob ject to examine
null
A Result
pair
Returns t if object is the empty list otherwise
object object
list
empty list proper list improper list
empty list
A generic prin method
proper list
object
A Sp ecialized Arguments
improper list
object object
nul l The empty list
stream The stream on which the representation is to
b e output
A Examples
the emptylist
A Result
a list whose car is and cdr is
The empty list
a pair whose car is and cdr is
a list whose car is and cdr is
A Remarks
Output the external representation of the empty list on
stream as describ ed ab ove
A cons class
The class of all instances of cons An instance of the class
A generic write method
cons also known informally as a dottedpair or a pair is
a tuple whose slots are called for historical reasons car
A Sp ecialized Arguments
and cdr Pairs are created by the function cons and the slots
are accessed by the functions car and cdr The ma jor use of
nul l The empty list
pairs is in the construction of prop er lists A prop er list
is de ned as either the empty list denoted by orapair
stream The stream on which the representation is to
whose cdr is a prop er list An improp er list is one containing
b e output
a cdr which is not a list see Table A
Programming Language EuLisp version
It is an error to apply car or cdr or their setter functions
to anything other than a pair The empty list is not a pair
A setter car setter
and car or cdr is an error
A Arguments
A consp function
pair A pair
object An ob ject
A Arguments
object Ob ject to examine
A Result
Given a pair such as the result of cons object object
A Result
then the function setter car replaces object with object
The result is object
Returns object if it is a pair otherwise
A setter cdr setter
A atom function
A Arguments
A Arguments
pair A pair
object Ob ject to examine
object An ob ject
A Result
Returns object if it is not a pair otherwise
A Result
Given a pair such as the result of cons object object
then the function setter cdr replaces object with object
A cons function
The result is object
A Arguments
A Remarks
Note that if object is not a prop er list then the use of
object An ob ject pair
setter cdr mightchange pair into an improp er list
object An ob ject pair
A equal method
A Result
Allo cates a new pair whose slots are initialize d with object
A Sp ecialized Arguments
in the car and object in the cdr
pair A pair
A car function
pair A pair
A Arguments
A Result
The result is the conjunction of the pairwise application of
pair A pair
equal to the car elds and the cdr elds of the arguments
A Result
Given a pair such as the result of cons object object
A deep copy method
then the function car returns object
A Sp ecialized Arguments
A cdr function
pair cons A pair
A Arguments
A Result
pair A pair
Constructs and returns a copy of the list starting at pair
copying b oth the car and the cdr slots of the list The list
can b e prop er or improp er Treatment of the ob jects stored
A Result
in the car slot and the cdr slot in the case of the nal pair
Given a pair such as the result of cons object object of an improp er list is determined bythedeep copy metho d
then the function cdr returns object for the class of the ob ject
Programming Language EuLisp version
A Result
A shallow copy method
The pair supplied as the rst argument
A Sp ecialized Arguments
A Remarks
Output the external representation of pair on stream as de
pair cons A pair
scrib ed at the b eginning of this section Uses generic write
to pro duce the external representation of the contents of the
car and cdr slots of pair
A Result
Constructs and returns a copy of the list starting at pair but
copying only the cdr slots of the list terminating when a
pair is encountered whose cdr slot is not a pair The list
b eginning at pair can b e prop er or improp er
A list function
A Arguments
object object A sequence of ob jects
n
A Result
Allo cates a set of pairs eachofwhich has b een initiali zed
with object in the car eld and the pair whose car eld
i
contains object in the cdr eld Returns the pair whose
i
car eld contains object
A Examples
list
list
A generic prin method
A Sp ecialized Arguments
pair cons The pair to b e output on stream
stream stream The stream on which the represen
tation is to b e output
A Result
The pair supplied as the rst argument
A Remarks
Output the external representation of pair on stream as de
scrib ed at the b eginning of this section Uses generic prin
to pro duce the external representation of the contents of the
car and cdr slots of pair
A generic write method
A Sp ecialized Arguments
pair cons The pair to b e output on stream
stream stream The stream on which the represen
tation is to b e output
Programming Language EuLisp version
operand list list The op erands passed to the op erator A Numb ers
The de ned name of this mo dule is number Numb ers can
A Remarks
takeonmany forms with unusual prop erties sp ecialized for
This is the general condition class for conditions arising from
di erent tasks but two classes of numb er su ce for the
arithmetic op erations
ma jority of needs namely integers A A and oat
ing p ointnumb ers A A Thus these only are de ned
at level
A division by zero arithmetic condition
In Figure A shows the initial numb er class hierar
chyatlevel The inheritance relationships by this
Signalled byanyofbinary binary and binary mod if
diagram are part of this de nition but it is not de
their second argument is zero
ned whether they are direct or not For example
integer and float are not necessarily direct sub
classes of number while the class of eachnumb er class
might b e a sub class of number class Since there are
A function
only two concrete numb er classes at level co ercion
is simple namely from fixed precision integer to
A Arguments
double float Anylevel version of a library mo dule for
example elementary functions need only de ne metho ds
number number A sequence of numbers
for these two classes Mathematicall y the reals are regarded
as a sup erset of the integers and for the purp oses of this def
integer even inition we regard float as a sup erset of
A Result
though this will cause representation problems when vari
Computes the sum of the arguments using the generic func
able precision integers are intro duced Hence float is
tion binary Given zero arguments returns of class
referred to as b eing higher that integer and arithmetic
integer One argument returns that argument The ar
involving instances of b oth classes will cause integers to b e
guments are combined left asso ciativel y
converted to an equivalent oating p ointvalue b efore the
calculation pro ceeds see in particular binary binary
and binary mod
A function
Figure A Level numb er class hierarchy
A Arguments
number number class
float number class
number number A non empty sequence of num
double float number class
b ers
integer number class
fixed precision integer number class
A Result
Computes the result of subtracting successive arguments
from the second to the last from the rst using the generic
A number class
function binary Zero arguments is an error One argument
returns the negation of the argument using the generic func
The abstract class which is the sup erclass of all number
tion negate The arguments are combined left asso ciatively
classes
A function
A numberp function
A Arguments
A Arguments
number number A sequence of numbers
object Ob ject to examine
A Result
A Result
Computes the pro duct of the arguments using the generic
Returns object if it is a numb er otherwise
function binary Given zero arguments returns of class
integer One argument returns that argument The argu
ments are combined left asso ciatively
A arithmetic condition condition
A function
A Initializati on Options
operator object The op erator which signalled the con
A Arguments
dition
number number A non empty sequence of num
This b ehaviour is p opularly referred to as oating point
contagion
b ers
Programming Language EuLisp version
A Result
A zerop generic function
Computes the result of dividing the rst argumentby its suc
ceeding arguments using the generic function binary Zero
arguments is an error One argument computes the recip
A Generic Arguments
ro cal of the argument It is an error in the single argument
case if the argument is zero
number Anumber
A function
A Result
Compares number with the zero element of the class of num
ber using the generic function binary
A Arguments
number number A non empty sequence of num
b ers
A negate generic function
A Result
A Generic Arguments
Computes the result of taking the remainder of dividing the
number number Anumber
rst argumentby its succeeding arguments using the generic
function binary Zero arguments is an error One argument
returns that argument
A Result
Computes the additiveinverse of number
A gcd function
A signum function
A Arguments
number number A non empty sequence of num
A Arguments
b ers
number Anumber
A Result
A Result
Computes the greatest common divisor of number up to
number using the generic function binary gcd Zero argu
n Returns number if zerop applied to number is true Oth
ments is an error One argumentreturnsnumber
erwise returns the result of converting to the class of
number with the sign of number
A lcm function
A positivep function
A Arguments
A Arguments
number number A non empty sequence of num
b ers
number Anumber
A Result
A Result
Computes the least common multiple of number up to
Compares number against the zero element of the class of
number using the generic function binary lcm Zero ar
number using the generic function binary
n
guments is an error One argument returns number
A negativep function
A abs function
A Arguments
A Arguments
number Anumber
number Anumb er
A Result
A Result
Compares number against the zero element of the class of
Computes the absolute value of number number using the generic function binary
Programming Language EuLisp version
number number Anumb er
A binary generic function
number number Anumb er
A Generic Arguments
A Result
number number Anumber
Computes the value of number inumber expressed as a
numb er of the class of the higher of the classes of the two
number number Anumber arguments for some integer i such that if number is non
zero the result has the same sign as number and magnitude
less then the magnitude of number If the second argument
A Result
is zero the result might b e zero or an error might b e signalled
condition class division by zero
Computes the sum of number and number
A binary mod generic function
A binary generic function
A Generic Arguments
A Generic Arguments
number number Anumb er
number number Anumber
number number Anumb er
number number Anumber
A Result
A Result
Computes the largest integral value not greater than
Computes the di erence of number and number
number number expressed as a numb er of the class of the
higher of the classes of the two arguments suchthatif
number is non zero the result has the same sign as number
A binary generic function
and magnitude less than number If the second argumentis
zero the result might b e zero or an error might b e signalled
condition class division by zero
A Generic Arguments
number number Anumber
A binary gcd generic function
number number Anumber
A Generic Arguments
A Result
number number Anumb er
Computes the pro duct of number and number
number number Anumb er
A binary generic function
A Result
Computes the greatest common divisor of number and
A Generic Arguments
number
number number Anumber
A binary lcm generic function
number number Anumber
A Generic Arguments
A Result
Computes the division of number by number expressed as
number number Anumb er
anumb er of the class of the higher of the classes of the two
arguments The sign of the result is p ositive if the signs the
number number Anumb er
arguments are the same If the signs are di erent the sign
of the result is negative If the second argument is zero the
result might b e zero or an error might b e signalled condition
A Result
class division by zero
Computes the lowest common multiple of number and
number
A binary generic function
A Generic Arguments
Programming Language EuLisp version
A Streams
A char file stream class
The de ned name of this mo dule is stream
The class of the default character le stream Often instances
Level streams only o er the most basic functional
of this stream typ e are p ositionable It is an error to make
ity supp orting character input and output on les via
an instance of this class byany other means than by the use
char file stream and character input and output on
of open
strings via string stream This functionality is imple
mented by the two generic functions input and output
A See also input output metho ds on
The b ehaviour at end of stream is governed by an option to
char file stream
open This option takes a eos action whichisacontinua
tion or some function of one argument as its value Up on
attempting to read b eyond the end of stream the value of
A string stream class
the stream s eos action is called with the stream as its argu
ment and the result of the call of eos action is returned as
the value of the input op eration This allows sp ecial actions
The class of the default string stream
to b e p erformed sp ecial values to b e returned or transfers
of control via continuations The default action is signal an
error condition class end of stream
A See also The converter metho d A for
string stream to string
A stream class
A standard input stream function
The abstract class of streams
This function takes no arguments
A streamp generic function
A Result
A stream which is the standard input stream
A Generic Arguments
A Remarks
object object The ob ject to b e examined
This stream is often the default for input functions
A Result
A standard output stream function
Returns object if it is a stream otherwise
This function takes no arguments
A file stream p generic function
A Result
A stream which is the standard output stream
A Generic Arguments
A Remarks
object object The ob ject to b e examined
This stream is often the default for output functions
A Result
A standard error stream function
Returns object if it is a stream held on some external
medium otherwise
This function takes no arguments
A character stream p generic function
A Result
A stream which is the standard error stream
A Generic Arguments
object object The ob ject to b e examined
A open function
A Arguments
A Result
Returns object if it is a character stream otherwise name A string
Programming Language EuLisp version
A Remarks options A sequence of options
Closes the stream It is an error to try to output to or input
from a closed stream
A Result
A stream
A flush generic function
A Remarks
A Generic Arguments
Options are input output update append and
eos action
stream stream A stream
If no options are sp eci ed input is assumed and
the eos action will signal an error condition class
A Result
end of stream
Returns t if the ush op eration was successful otherwise
The eos action option takes a stream action a continua
tion or a function of one argument as an argument Up on
an attempt to read b eyond the end of the stream this stream
A Remarks
action is called with the stream as argument and the value
flush causes any bu ered data for the stream to b e written
returned by the stream action is the value returned by the
to the stream The stream remains op en
reading op eration If the eos action is omitted the de
fault stream action is to signal an error condition class
end of stream
A stream position generic function
It is an error to combine the input option with output
update or append It is an error to combine the output
A Generic Arguments
option with input
stream stream A stream
A Examples
open foo Op en the le foo for
A Result
input
Returns a non negativeinteger indicating the current p osi
for output open bar output append Op en bar
tion within the stream or if it cannot b e determined
app ending to its end
A self resetting stream op en le c
eos action
A Remarks
lamb da s
setter stream p osition s
The value returned by stream position increases mono
read s
tonically as input output op erations are p erformed Gen
erally this value maybeusedinacallof setter
stream position on the same stream
A end of stream stream condition
A setter stream position generic function
A Initializati on Options
A Generic Arguments
stream stream A stream
stream stream A stream
A Remarks
position object An integer or the symbol
stream end
Signalled by the default end of stream action as a conse
quence of an input op eration on stream when it is at end of
stream
A Result
Returns t if the p ositionin g op eration was successful other
wise
A close generic function
A Generic Arguments
A Remarks
If position is an integer this sets the p osition of the stream to
stream stream A stream
b e that value If position is stream end this sets the p osition
of the stream to b e the end of the stream The value is
returned if the stream is not p ositionabl e If the value of posi
A Result
tion is to o large or is otherwise inappropriate an error is sig
Returns t if the close op eration was successful otherwise nalled condition class inappropriate stream position
Programming Language EuLisp version
A Remarks
A end of stream p function
Outputs the ob ject to stream
This mo dule de nes four metho ds on output two for char
A Arguments
acter le streams and two for string streams In eachcase
the metho ds sp ecialize on characters or sequences
stream A stream
A read line generic function
A Result
Returns t if stream is exhausted otherwise
A Generic Arguments
stream stream A stream
A input generic function
A Result
A Generic Arguments
A string
stream stream A stream
A Remarks
A Result
Reads a line terminated byanewlinecharacter or the end
Reads and returns a single ob ject from the stream The typ e
of the stream from the stream of characters whichisstream
of the ob ject returned dep ends on the typ e of the stream
Returns the line as a string discarding the terminating new
line if any If the stream is already at end of stream then
the stream action is called the default stream action is to
A Remarks
signal an error condition class end of stream
This mo dule de nes two metho ds on input one for character
le streams and one for string streams Both metho ds return
characters
A prin function
A uninput generic function
A Arguments
object An ob ject to b e output on stream
A Generic Arguments
stream Acharacter stream on which object is to b e
stream stream A stream
output
object object
A Result
Returns object
A Result
Returns t
A Remarks
Outputs the external representation of object on the output
A Remarks
stream stream using generic prin Ifstream is not sp eci ed
Replaces object backonto the input stream It is an error if
the standard output stream is used
the ob ject was not the last thing to b e returned by input
This mo dule de nes two metho ds on uninput one for char
A See also standard output stream
generic prin acter le streams and one for string streams Both metho ds
sp ecialize on characters for the second argument
A print function
A output generic function
A Arguments
A Generic Arguments
object An ob ject to b e output on stream
stream stream A stream
stream Acharacter stream on which object is to b e
output object object An ob ject
A Result A Result
Returns object Returns object
Programming Language EuLisp version
A Result A Remarks
Returns object
Outputs the external representation of object on the output
stream stream using generic prin followed by a newline
character If stream is not sp eci ed the standard output
A Remarks
stream is used
Outputs the external representation of object on the output
stream stream
A See also standard ouptut stream
generic prin
A See also metho ds on generic prin are de ned
for character A double float
A fixed precision integer A list A
A write function
string A symbol A and vector A
A Arguments
A generic write generic function
object An ob ject to b e output on stream
A Generic Arguments
stream Acharacter stream on which object is to b e
output
object object An ob ject to b e output on stream
stream stream A stream on which object is to b e
A Result
output
Returns object
A Result
A Remarks
Returns object
Outputs the external representation of object on the output
stream stream using generic write Ifstream is not sp eci
ed the standard output stream is used
A Remarks
Outputs the external representation of object on the output
stream stream
A See also standard output stream
generic write
A See also Metho ds on generic write are de
ned for character A double float
A fixed precision integer A list A
A newline function
string A symbol A and vector A
A Arguments
A converter string method
stream A stream on which the newline is to b e out
put
A Sp ecialized Arguments
A Result
stream string stream A string stream
Returns newline
A Result
The currentvalue of the string asso ciated with stream
A Remarks
Outputs a newline character on stream If stream is not
sp eci ed the standard output stream is used
A Remarks
The currentvalue is reset to the empty string after the call
to converter
A See also standard output stream
A generic prin generic function
A Generic Arguments
object object An ob ject to b e output on stream
stream stream A stream on which object is to b e
output
Programming Language EuLisp version
Table A String Syntax
A Strings
The de ned name of this mo dule is string See also sec
tion A collections for further op erations on strings string token
string constituent
string constituent
normal string constituent
A string syntax
digram string constituent
numeric string constituent
normal string constituent
String literals are delimited by the glyph called quotation
level character
mark For example abcd
digram string constituent
a alert
b backspace
Sometimes it might b e desirable to include string delimiter
d delete
characters in strings The aim of escaping in strings is to ful
f formfeed
ll this need The string escape glyph is de ned as reverse
l linefeed
solidus String escaping can also b e used to include cer
n new line
tain other characters that would otherwise b e di cult to
r return
denote The set of named sp ecial characters see sections
t tab
and A have a particular syntax to allow their inclusion in
v vertical tab
strings Toallow arbitrary characters to app ear in strings string delimiter
string escape
the hex insertion digram is followed byaninteger denoting
numeric string constituent
the p osition of the character in the currentcharacter set
x hex digit
Some examples of string literals app ear in Table A The
x hex digit hex digit
syntax for the external representation of strings is de ned in
x hex digit hex digit hex digit
Table A
x hex digit hex digit hex digit
hex digit
NOTE At present this do cument refers to the currentchar
acter set but de nes no means of selecting alternativecharacter
sets This is to allow for future extensions and implementation
de ned extensions which supp ort more than one character set
size fixed precision integer The number
Table A Examples of string literals
of characters in the string Strings are zero based and
thus the maximum index is size If not sp eci ed the size
Example Contents
is zero
a nb a newline and b
c c and
fill value character Acharacter with whichto
x x followed by space
initiali ze the string The default ll character is x
xabcde xabcd followed by e
x x x followed by x
x x followed by
A Examples
xabcg xabc followed by g
x abc xab followed by c
make string
make string size x x
make string size aaa
The function write outputs a re readable form of any es
fill value a
cap ed characters in the string For example a n b input
notation is the string containing the characters newline
a and b The function write pro duces a n b
whilst prin pro duces
A stringp function
a
b
A Arguments
The function write outputs characters which do not have
object Ob ject to examine
a glyph asso ciated with their p osition in the character set
as a hex insertion in which all four hex digits are sp eci ed
even if there are leading zeros as in the last example in
A Result
Table A The function prin outputs the interpretation
of the characters according to the de nitions in section A
Returns object if it is a string otherwise
without the delimiting quotation marks
A converter symbol method
A string class
A Sp ecialized Arguments
The class of all instances of string
string string A string to b e convertedtoasym
bol
A Initializati on Options
Programming Language EuLisp version
A Examples A Result
If the result of symbol exists p when applied to string is a
a b t
symb ol that symb ol is returned If the result is then a
b a
new symb ol is constructed whose name is string This new
a a
symb ol is returned
a ab t
ab a
A B t
t
A equal method
a a t
a bb t
A Sp ecialized Arguments
a ab unde ned
string string A string
A See also Metho d on binary A for characters
string string A string
A
A Result
If the size of string is the same under as that of string
A as lowercase method
then the result is the conjunction of the pairwise application
of equal to the elements of the arguments If not the result
is
A Sp ecialized Arguments
string string A string
A deep copy method
A Result
A Sp ecialized Arguments
Returns a copyofstring in whicheachcharacter denoting an
string string A string
upp er case character is replaced byacharacter denoting its
lower case counterpart The result must not b e eq to string
A Result
Constructs and returns a copyofstring in which eachele
mentiseql to the corresp onding elementinstring
A as uppercase method
A Sp ecialized Arguments
A shallow copy method
string string A string
A Sp ecialized Arguments
string string A string
A Result
Returns a copyofstring in whicheachcharacter denoting an
A Result
lower case character is replaced byacharacter denoting its
Constructs and returns a copyofstring in which eachele
upp er case counterpart The result must not b e eq to string
mentiseql to the corresp onding elementinstring
A generic prin method
A binary method
A Sp ecialized Arguments
A Sp ecialized Arguments
string string String to b e ouptut on stream
string string A string
string string A string
stream stream Stream on which string is to b e
ouptut
A Result
If the second argument is longer than the rst the result
A Result
is Otherwise if the sequence of characters in string is
pairwise less than that in string according to binary the The string string
result is t Otherwise the result is Since it is an error
to compare lower case upp er case and digit characters with Output external representation of string on stream as de
any other kind than themselves so it is an error to compare scrib ed in the intro duction to this section interpreting each
two strings which require such comparisons and the results of the characters in the string The op ening and closing quo
are unde ned tation marks are not output
Programming Language EuLisp version
A Symbols
A generic write method
The de ned name of this mo dule is symbol
A Sp ecialized Arguments
A symbol syntax
string string String to b e ouptut on stream
stream stream Stream on which string is to b e
The syntax of symb ols also serves as the syntax for identi
ouptut
ers Identi ers in EULISP are very similar lexically to iden
ti ers in other Lisps and in other programming languages
Informally anidenti er is a sequence of alphabetic digit and
A Result
other characters starting with a character that is not a digit
The string string
Characters which are special see section must b e escap ed
if they are to b e used in the names of identi ers However
Output external representation of string on stream as de
b ecause the common notations for arithmetic op erations are
scrib ed in the intro duction to this section replacing single
the glyphs for plus and minus which are also used
characters with escap e sequences if necessary Op ening and
to indicate the sign of a numb er these glyphs are classi ed
closing quotation marks are output
as identi ers in their own rightaswell as b eing part of the
syntax of a number
Sometimes it might b e desirable to incorp orate characters
in an identi er that are normally not legal constituents The
aim of escaping in identi ers is to change the meaning of
particular characters so that they can app ear where they are
not otherwise acceptable Identi ers containing characters
that are not ordinarily legal constituents can b e written by
delimiting the sequence of characters by multiple escape the
glyph for which is called vertical bar The multiple escape
denotes the b eginning of an escap ed part of an identi er and
the next multiple escape denotes the end of an escap ed part
of an identi er A single character that would otherwise not
b e a legal constituent can b e written by preceding it with
single escape the glyph for which is called reverse solidus
Therefore single escape can b e used to incorp orate the
multiple escape or the single escape character in an identi er
delimited or not by multiple escape s For example
is the identi er whose name contains the three characters
and anda b is the identi er whose name
contains the characters a and b The sequence is
the identi er with no name and so is but is the
identi er whose name contains the single character which
can also b e written without delimitin g multiple escape s
Any identi er can b e used as a literal in which cases it de
hanisms notes a symbol Because there are two escaping mec
and b ecause the rst character of a token a ects the inter
pretation of the remainder there are manyways in whichto
input the same identi er If this same identi er is used as a
literal the results of pro cessing each token denoting the iden
ti er will b e eq to one another For example the following
tokens all denote the same symbol
whichwillbeoutputby the function write as If out
put by write the representation of the symb ol will p ermit
reconstruction by read escap e characters are preserved
so that equivalence is maintained b etween read and write
for symbols For example a b and abc def are two sym
b ols as output by write such that read can read them as
twosymb ols If output by prin the escap es necessary to
re read the symb ol will not b e included Thus taking the
same examples prin outputs a b and abc def which read
interprets as the symbol a followed by the start of a list the
symbol b and the symbol abc def
The syntax of the external representation of identi ers and
Programming Language EuLisp version
Table A Identi er Symb ol Syntax
A Result
Makes a new symb ol whose name by default b egins with
the character g and the remaining characters are generated
symbol
by an implementation de n ed mechanism Optionally an
identifier
alternative pre x string for the name may b e sp eci ed It
identifier
is guaranteed that the resulting symb ol did not exist b efore
normal identifier peculiar identifier
the call to gensym
normal identifier
normal initial normal constituent
normal initial
letter
A symbol name function
other character
normal constituent
letter
A Arguments
digit
other character
symbol Asymbol
peculiar identifier
peculiar constituent
normal constituent
A Result
peculiar constituent normal constituent
peculiar constituent
Returns a string whichisequal to that given as the argu
letter
ment to the call to make which created symbol Itisanerror
other character
to mo dify this string
A symbol exists p function
symb ols is de ned in Table A
A Arguments
Computationally the most imp ortant asp ect of symbols is
that each is unique or stated the other way around the re
string A string containing the characters to b e used to
sult of pro cessing every syntactic token comprising the same
determine the existence of a symb ol with that name
sequence of characters which denote an identi er is the same
ob ject Or more brie y every identi er with the same name
denotes the same symb ol
A Result
Returns the symb ol whose name is string if that symb ol has
already b een constructed by make Otherwise returns
A symbol class
The class of all instances of symbol
A generic prin method
A Initializati on Options
A Sp ecialized Arguments
string string The string containing the characters to
symbol symbol The symb ol to b e output on stream
b e used to name the symb ol The default value for string
is the empty string thus resulting in the symb ol with no
stream stream The stream on which the represen
name written
tation is to b e output
A Result
A symbolp function
The symb ol supplied as the rst argument
A Arguments
A Remarks
object Ob ject to examine
Outputs the external representation of symbol on stream as
describ ed in the intro duction to this section interpreting
eachofthecharacters in the name
A Result
Returns object if it is a symbol
A generic write method
A gensym function
A Sp ecialized Arguments
symbol symbol The symb ol to b e output on stream A Arguments
stream stream The stream on which the represen string A string contain characters to b e prep ended to
tation is to b e output the name of the new symbol
Programming Language EuLisp version
A Result A Tables
The symb ol supplied as the rst argument
The de ned name of this mo dule is table See also sec
tion A collections for further op erations on tables
A Remarks
Outputs the external representation of symbol on stream as
A table class
describ ed in the intro duction to this section If anycharac
ters in the name would not normally b e legal constituents of
an identi er or symb ol the output is preceded and succeeded
The class of all instances of table
bymultiple escap e characters
A Initializati on Options
A Examples
write make symbol string abc abc
comparator function The function to b e used to
write make symbol string a c a c
compare keys The default comparison function is eql
write make symbol string
fill value object An ob ject which will b e returned
as the default value for anykey which do es not havean
asso ciated value The default ll value is
A converter string method
hash function function The function to b e used to
A Sp ecialized Arguments
compute an unique key for each ob ject stored in the table
This function must return a xed precision integer The
symbol symbol Asymboltobeconverted to a
hash function must also satisfy the constraint that if the
string
comparison function returns true for anytwo ob jects then
the hash function must return the same key when applied
to those two ob jects The default is an implementation
A Result
de ned function which satis es these conditions
A string
A tablep function
A Remarks
This function is the same as symbol name It is de ned for
A Arguments
the sake of symmetry
object Ob ject to examine
A Result
Returns object if it is a table otherwise
A clear table function
A Arguments
table A table
A Result
An empty table
A Remarks
All entries in table are deleted The result is eq to the argu
ment whichistosay that the argument is mo di ed
Programming Language EuLisp version
pro cessor must supp ort a maximum vector index of at least A Vectors
The de ned name of this mo dule is vector See also sec
tion A collections for further op erations on vectors
A equal method
A vector syntax
A Sp ecialized Arguments
vector vector Avector
Avector is written as obj obj For example
n
is a vector of three elements the integers and
vector vector Avector
The representations of obj are determined by the exter
i
nal representations de ned in other sections of this de ni
tion see character A fixed precision integer
A Result
A float A list A string A and
If the size of vector is the same under asthatofvector
symbol A as well as instances of vector itself The
then the result is the conjunction of the pairwise application
syntax for the external representation of vectors is de ned
of equal to the elements of the arguments If not the result
in Table A
is
Table A Vector Syntax
A deep copy method
vector
object
A Sp ecialized Arguments
vector vector Avector
A vector class
A Result
Constructs and returns a copyofvector inwhicheach ele
The class of all instances of vector
ment is the result of calling deep copy on the corresp onding
elementofvector
A Initializati on Options
A shallow copy method
size fixed precision integer The number of ele
ments in the vector Vectors are zero based and thus the
maximum index is size If not supplied the size is zero
A Sp ecialized Arguments
fill value object An ob ject with which to initial
vector vector Avector
ize the vector The default ll value is
A Result
A Examples
Constructs and returns a copyofvector in whicheach ele
make vector
mentiseql to the corresp onding elementinvector
make vector size
make vector size a a a
fill value a
A generic prin method
A vectorp function
A Sp ecialized Arguments
vector vector Avector to b e ouptut on stream
A Arguments
stream stream A stream on which the representa
object Ob ject to examine
tion is to b e output
A Result
A Result
Returns object if it is a vector otherwise
The vector supplied as the rst argument
A Remarks
A maximum vector index integer
Output the external representation of vector on stream as de
scrib ed in the intro duction to this section Calls the generic
A Remarks
function again to pro duce the external representation of the
This is an implementation de ned constant A conforming elements stored in the vector
Programming Language EuLisp version
A Syntax of Level ob jects
A generic write method
This section rep eats the syntax for reading and writing of
the various classes de ned in Annex A
A Sp ecialized Arguments
object
character A
vector vector Avector to b e ouptut on stream
float A
integer A
stream stream A stream on which the representa
list A
tion is to b e output
string A
symbol A
vector A
A Remarks
Output the external representation of vector on stream as de
scrib ed in the intro duction to this section Calls the generic
character token
function again to pro duce the external representation of the
literal character token
special character token elements stored in the vector
control character token
numeric character token
literal character token
letter
decimal digit
non alphabetic
control character token
letter
special character token
alert
backspace
delete
formfeed
linefeed
newline
return
tab
space
vertical tab
numeric character token
x hex digit
x hex digit hex digit
x hex digit hex digit hex digit
x hex digit hex digit hex digit
hex digit
float
sign unsigned float exponent
sign
unsigned float
float format
float format
float format
float format
decimal integer A
float format
decimal integer A
float format
float format decimal integer A
exponent
double exponent A
double exponent
d D sign decimal integer A
Programming Language EuLisp version
integer string token
sign unsigned integer string constituent
sign string constituent
normal string constituent
unsigned integer digram string constituent
binary integer numeric string constituent
octal integer normal string constituent
decimal integer level character
hexadecimal integer digram string constituent
specified base integer a alert
binary integer b backspace
b binary digit binary digit d delete
binary digit f formfeed
l linefeed
octal integer n new line
eturn o octal digit octal digit r r
t tab octal digit
v vertical tab
string delimiter decimal integer
string escape decimal digit decimal digit
numeric string constituent hexadecimal integer
x hex digit x hexadecimal digit hexadecimal digit
x hex digit hex digit hexadecimal digit
x hex digit hex digit hex digit decimal digit
x hex digit hex digit hex digit hex lower letter
hex digit hex upper letter
hex lower letter
a b c d e f
hex upper letter
symbol
A B C D E F
identifier
specified base integer
identifier
base specification r
normal identifier peculiar identifier
specified base digit
normal identifier
specified base digit
normal initial normal constituent
base specification
normal initial
decimal digit
letter
decimal digit
other character
normal constituent
specified base digit
letter
decimal digit letter
digit
other character
peculiar identifier
peculiar constituent null
normal constituent
peculiar constituent normal constituent pair
peculiar constituent object object
letter list
other character empty list proper list improper list
empty list
proper list
vector
object
object
improper list
object object
Programming Language EuLisp version
Annex B
normative
Programming Language EuLisp Level
initial value of the slot This option must only b e sp eci ed B Classes and Ob jects
once for a particular slot The same initarg name maybe
used for several slots in which case they will share the
B defclass de ning form
same initial value if the initarg is given to make
initform form The value of this option is a form which
B Syntax
is evaluated as the default value of the slot to b e used if
no initarg is de ned for the slot or given to a call to make
defclass form The form is evaluated in the lexical environment of the call
defclass
to defstruct and the dynamic environment of the call to
class name
make The form is evaluated each time make is called and
superclass list
the default value is called for The order of evaluation of
defclass slot description list
the initforms in all the slots is determined by initialize
defclass class option
This option must only b e sp eci ed once for a particular
superclass list
slot
superclass name
defclass slot description list
reader symbol The value is the identi er of the variable
defclass slot description
defclass slot option
to which the reader function will b e b ound The reader
initform level expression
function is a means to access the slot The reader func
identifier level expression
tion is a function of one argument which should b e an
defstruct slot option
instance of the new class No writer function is automati
defclass class option
cally b ound with this option This option can b e sp eci ed
class class name
more than once for a slot creating several readers It is an
identifier level expression
error to sp ecify the same reader writer or accessor name
defstruct class option
for two di erent slots
writer symbol The value is the identi er of the variable
to which the writer function will b e b ound The writer
B Arguments
function is a means to change the slot value The creation
of the writer is analogous to that of the reader function
class name A symb ol naming a binding to b e initiali sed
This option can b e sp eci ed more than once for a slot It
with the new class
is an error to sp ecify the same reader writer or accessor
name for t wo di erentslots
superclass A list of symb ols naming bindings of
classes to b e used as the sup erclasses of the new class
accessor symbol The value is the identi er of the vari
This is di erent from defstruct at level where only
able to which the reader function will b e b ound In ad
one sup erclass may b e sp eci ed
dition the use of this slot option causes that the writer
function is asso ciated to the reader via the setter mech
slot description A list of slot sp eci cations see b e
anism This option can b e sp eci ed more than once for a
low comprising either a slot name or a list of a slot name
slot It is an error to sp ecify the same reader writer or
followed by some slot options One of the class options
accessor name for two di erentslots
see b elow allows the sp eci cation of the class of the slot
description
identi er expression The symb ol named by identi er
and the value of expression are passed to make of the slot
class option A sequence of keys and values see b elow
description class along with other slot options The values
One of the class options class allows the sp eci cation
are evaluated in the lexical and dynamic environmentof
of the class of the class b eing de ned
the defclass For the language de ned slot description
classes no slot initargs are de ned which are not sp eci ed
B Remarks
by particular defclass slot options
This de ning form de nes a new class The resulting class
The class option s are interpreted as follows
will b e b ound to class name The second argument is a list of
sup erclasses If this list is empty the sup erclass is object
initargs list The value of this option is a list of iden
The third argument is a list of slot descriptions The remain
ti ers naming symbols which extend the inherited names
ing arguments are class options All the slot options and class
of arguments to b e supplied in the init option s of a call
options are exactly the same wayasfordefstruct
to make on the new class Initargs are inherited by union
The values of all legal arguments in the call to make are the
The slot option s are interpreted as follows
initial values of corresp onding slots if they name a slot or
are ignored by the default initialize metho d otherwise
initarg symbol The value of this option is a identi er
This option must only b e sp eci ed once for a class
naming a symb ol which is the name of an argumenttobe
init option s of a call to make on the new supplied in the
class The value of this argument in the call to make is the Creates a constructor constructor constructor spec
Programming Language EuLisp version
which defaults to method and non standard options The function for the new class The constructor sp eci cation
latter are evaluated in the lexical and dynamic environment gives the name to which the constructor function will b e
of generic lambda and passed to make of the generic func b ound followed by a sequence of legal initargs for the class
tion as additional initiali zati on arguments The additional The new function creates an instance of the class and lls
init option sover level are interpreted as follows in the slots according to the matchbetween the sp eci ed
initargs and the given arguments to the constructor func
class gf class The class of the new generic function tion This option may b e sp eci ed more than once
This must b e a sub class of generic function The de
fault is generic function predicate symbol Creates a predicate function for the
new class The predicate sp eci cation gives the name to
method class method class The class of all metho ds to which the predicate function will b e b ound This option
b e de ned on this generic function All metho ds of a may b e sp eci ed anynumb er of times for a class
generic function must b e instances of this class The
method class must b e a sub class of method and defaults class class The value of this option is the class of the
to method new class By default this is class This option must
only b e sp eci ed once for the new class
identi er expression The symb ol named by identi er
and the value of expression are passed to make as initargs identi er expression The symb ol named by identi er
and the value of expression are passed to make on the class
The values are evaluated in the lexical and dynamic envi
ronment of the defgeneric This option is used for classes of the new class This list is app ended to the end of the
list that defclass constructs The values are evaluated
which need extra information not provided by the stan
dard options in the lexical and dynamic environment of the defclass
This option is used for metaclasses which need extra in
In addition metho d init options can b e sp eci ed for the indi formation not provided by the standard options
vidual metho ds on a generic function These are interpreted
as follows
B Generic Functions
class method class The class of the metho d to b e de
ned The metho d class must b e a sub class of method
B generic lambda macro
and is by default method Thevalue is passed to make
as the rst argument The symb ol and the value are not
passed as initargs to make
B Syntax
identi er expression The symb ol named by identi er
generic lambda form
and the value of expression are passed to make creating
generic lambda gf lambda list
a new metho d as initargs The values are evaluated in the
level init option
lexical and dynamic environment of the generic lambda
level init option
This option is used for classes which need extra informa
class class name
tion not provided by the standard options
method class class name
method level method description
identifier level expression
B Examples
level init option
level method description
In the following example an anonymous version of gf see
method init option
defgeneric is de ned In all other resp ects the resulting
specialized lambda list
ob ject is the same as gf
form
method init option
generic lambda arg arg class a
class class name
identifier level expression
class another gf class
class key a class value a
class key b class value b
B Arguments
method class another method class a
gf lambda list As level See section
method class another method class b
method class b key a method class b value a
level init option Format as level but with addi
m arg class b m arg class c
tional options which are de ned b elow
method method class a key a method class a value a
m arg class d m arg class e
B Result
method class another method class c
A generic function
method class c key a method class c value a
m arg class f m arg class g
B Remarks
The syntax of generic lambda is an extension of the level
syntax allowing additional init options These allow the
sp eci cation of the class of the new generic function which
B See also defgeneric defaults to generic function the class of all metho ds
Programming Language EuLisp version
method class another method class b
method class b key a method class b value a
B defgeneric de ning form
m arg class b m arg class c
a method class a value a method method class a key
B Syntax
m arg class d m arg class e
method class another method class c
defgeneric form
method class c key a method class c value a
defgeneric
m arg class f m arg class g
gf name
gf lambda list
level init option
B Metho ds
B Arguments
gf name As level See section
B method lambda macro
gf lambda list As level See section
init option As for generic lambda de ned ab ove b e
B Syntax
low
method lambda form
method lambda
B Remarks
method init option B
This de ning form de nes a new generic function The re
specialized lambda list
sulting generic function will b e b ound to gf name The sec
form
ond argument is the formal parameter list An error is sig
nalled condition non congruent lambda lists ifanyof
the metho ds de ned on this generic function do not have
lamb da lists congruent to that of the generic function This
B Arguments
applies b oth to metho ds de ned at the same time as the
generic function and to any metho ds added subsequently by
method init option A quoted symb ol followed byanex
defmethod or add method Aninit option is a identi er fol
pression
lowed by its initial value The syntax of defgeneric is an
extension of the level syntax The rewrite rules for the
specializedlambda list As de ned under
defgeneric form are identical to those given in Table ex
generic lambda
cept that level init option replaces level init option
form An expression
B Examples
In the following example of the use of defgeneric a generic
function named gf is de ned The di erences b etween this
B Result
function and gf see are
This syntax creates and returns an anonymous metho d with
the given lamb da list and b o dy Thisanonymous metho d
a The class of the generic function is sp eci ed
can later b e added to a generic function with a congruent
another gf class along with some init options re
lamb da list via the generic function add method Note that
lated to the creation of an instance of that class
the lamb da list can b e sp ecialized to sp ecify the metho d s do
main The value of the sp ecial initarg class determines the
b The default class of the metho ds to b e attached to the
class to instantiate the rest of the initlist is passed to make
generic function is sp eci ed another method class a
called with this class The default metho d class is method
along with an init option related to the creation of an in
stance of that class
B Remarks
c In addition some of the metho ds to b e attached are
of a di erent metho d class another method class b
The additional method init option s includes class for sp eci
and another method class c also with metho d sp e
fying the class of the metho d to b e de ned and non standard
ci c init options These metho d classes are sub classes of
options which are evaluated in the lexical and dynamic en
another method class a
vironmentofmethod lambda and passed to initialize of
that metho d
defgeneric gf arg arg class a
class another gf class
B defmethod macro
class key a class value a
class key b class value b
method class another method class a
B Syntax
Programming Language EuLisp version
method A metho d
defmethod form
next methods A list of metho ds
defmethod gf name
method init option B
specialized lambda list
form form A sequence of expressions
n
form
form An expression
n
This function is identical to call method except that its last
B Remarks
argument is a list whose elements are the other arguments
to pass to the metho d s metho d function The di erence is
The defmethod form of level extends that of level to ac
the same as that b etween normal function application and
cept method init option s This allows for the sp eci cation of
apply
the metho d class by means of the class init option This
class must b e a sub class of the metho d class of the host
generic function The metho d class otherwise defaults to
that of the host generic function In all other resp ects the
B call method function function
b ehaviour is as that de ned in level
B Arguments
B method function lambda macro
method fn A metho d function
B Arguments
next methods A list of metho d functions
lambda list A lambda list
A sequence of expressions form
form A sequence of forms
This function calls the metho d function method fn with ar
guments args The method fn must have b een created by
This macro creates and returns an anonymous metho d func
method function lambda The argument next methods is a
tion with the given lamb da list and b o dy This anony
list of metho d functions which are used as the applicabl e
mous metho d function can later b e added to a metho d using
metho d list for the form s it is an error if this list is di erent
setter method function orasthe function initiali za
from the metho d functions in the list of metho ds whichwould
tion value in a call of make on an instance of method A
b e pro duced by the metho d lo okup function of the generic
function of this typ e is also returned by the metho d acces
function of the metho d to which the metho d function is at
sor method function and can b e called using the sp ecial
tached These metho d functions are used to determine the
metho d function calling functions call method function
next metho d to call when call next method is called within
and apply method function Only functions created using
method fn
this macro can b e used as metho d functions Note that the
lamb da list must not b e sp ecialized a metho d s domain is
stored in the metho d itself
B apply method function function
B Arguments
B call method function
method fn A metho d function
B Arguments
next methods A list of metho d functions
method A metho d
form form A sequence of expressions
n
next methods A list of metho ds
form An expression
n
arg A sequence of expressions
This function is identical to call method function except
This function calls the metho d method with arguments args
that its last argument is a list whose elements are the other
The argument next methods is a list of metho ds which are
arguments to pass to the metho d function The di erence is
used as the applicabl e metho d list for args it is an error if this
the same as that b etween normal function application and
list is di erent from the metho ds whichwould b e pro duced
apply
by the metho d lo okup function of the generic function of
method If method is not attached to a generic function
its b ehavior is unsp eci ed The next methods are used to
determine the next metho d to call when call next method
is called within method fn
B apply method function
B Arguments
Programming Language EuLisp version
object abstract class
B Ob ject Introsp ection
class class
abstract class class
The only re ective capability whichevery ob ject p ossesses is
function class class
the ability to nd its class
slot description abstract class
local slot description class
function abstract class
B class of function
generic function function class
method class
B Arguments
Figure B Level class hierarchy
object An ob ject
e The initarg whichisasymb ol to access the value
B Result
which can b e supplied to a make call in order to initializ e
The class of the ob ject
the corresp onding slot in a newly created ob ject
The metaob ject classes de ned for slot descriptions at level
B Remarks
are shown in Table B
The function class of can takeany LISP ob ject as argument
and returns an instance of class representing the class of
that entity
B class precedence list function
B Class Introsp ection
B Arguments
Standard classes are not rede nable and supp ort single in
class A class
heritance only General multiple inheritance or mixin in
heritance can b e provided by extensions Nor is it p ossi
ble to use a class as a sup erclass which is not de ned at
B Result
the time of class de nition Again such forward reference
A list of classes starting with class itself suc
facilities can b e provided by extensions The distinction
ceeded by the sup erclasses of class and ending with
between metaclasses and non metaclasses is made explicit
object This list is equivalent to the result of calling
by a sp ecial class named metaclass which is the class
compute class precedence list
of all metaclasses This is di erent from Ob jVlisp where
whether a class is a metaclass dep ends on the sup erclass list
of the class in question It is implementation de ned whether
B Remarks
metaclass itself is sp ecializab le or not This implies that
implementations are free to restrict the instantiation tree The class precedence list is used to control the inheritance
excluding the sel nstantiati on lo op of metaclass toa of slots and metho ds
depth of three levels
The minimum information asso ciated with a class metaob
B class slot descriptions function
ject is
a The class precedence list ordered most sp eci c rst
B Arguments
b eginning with the class itself
class A class
b The list of e ective slot descriptions
c The list of e ective initargs
B Result
A list of slot descriptions one for each of the slots of an
Standard classes supp ort lo cal slots only Shared slots can b e
instance of class
provided by extensions The minimal information asso ciated
with a slot description metaob ject is
B Remarks
a The name which is required to p erform inheritance
The slot descriptions determine the instance size number of
computations
slots and the slot access
b The initfunction called by default to compute the
initial slot value when creating a new instance
B class initargs function
c The reader which is a function to read the corresp ond
ing slot value of an instance
B Arguments
d The writer which is a function to write the corre
class A class
sp onding slot of an instance
Programming Language EuLisp version
B Result B Result
Alistofsymb ols which can b e used as legal keywords to
A function of no arguments that is used to compute the
initiali ze instances of the class
initial value of the slot in the absence of a supplied value
B Remarks
B slot description slot reader function
The initargs corresp ond to the keywords sp eci ed in the
initarg slot option or the initargs class option when the
class and its sup erclasses were de ned
B Arguments
slot description A slot description
B Slot Introsp ection
B Result
B slot description class
A function of one argument that returns the value of the slot
in that argument
The abstract class of all slot descriptions
B slot description slot writer function
B local slot description class
B Arguments
The class of all lo cal slot descriptions
slot description A slot description
B Initializati on Options
B Result
name string The name of the slot
A function of two arguments that installs the second argu
ment as the value of the slot in the rst argument
reader function The function to access the slot
writer function The function to up date the slot
B Generic Function Introsp ection
initfunction function The function to compute the
The default generic dispatchscheme is class based that is
initial value in the absence of a supplied value
metho ds are class sp eci c The default argument precedence
order is left to right
initarg symbol The key to access a supplied initial
value
The minimum information asso ciated with a generic function
metaob ject is
The default value for all initoptions is false
a The domain restricting the domain of eachadded
metho d to a sub domain
B slot description name function
b The metho d class restricting each added metho d to
b e an instance of that class
B Arguments
c The list of all added metho ds
slot description A slot description
d The metho d lo ok up function used to collect and sort
B Result
the applicabl e metho ds for a given domain
The symb ol whichwas used to name the slot when the class
e The discriminati ng function used to p erform the
of which the slot descriptio n is part was de ned
generic dispatch
B Remarks
The slot description name is used to identify a slot descrip
B generic function domain function
tion in a class It has no e ect on bindings
B Arguments
B slot description initfunction function
generic function A generic function
B Arguments
B Result
slot description A slot description
A list of classes
Programming Language EuLisp version
B Result B Remarks
This function returns the domain of a generic function The
A function
domains of all metho ds attached to a generic function are
constrained to b e within this domain In other words the
domain classes of each metho d must b e sub classes of the
B Remarks
corresp onding generic function domain class It is an error
This function returns a function whichmay b e applied
to mo dify this list
to the same arguments as the generic function This
function is called to p erform the generic dispatchoper
ation to determine the applicable metho ds whenever the
B generic function method class function
generic function is called and call the most sp eci c ap
plicable metho d function This function is created by
compute discriminating function
B Arguments
generic function A generic function
B Metho d Introsp ection
The minimal information asso ciated with a metho d metaob
B Result
ject is
This function returns the class which is the class of all meth
o ds of the generic function Each metho d attached to a
a The domain which is a list of classes
generic function must b e an instance of this class When
a metho d is created using defmethod method lambda orby
b The function comprising the co de of the metho d
using the method generic function option in a defgeneric
or generic lambda it will b e an instance of this class by
c The generic function to which the metho d has b een
default
added or if it is attached to no generic function
The metaob ject classes for generic functions de ned at level
B generic function methods function
are shown in Table B
B Arguments
B method domain function
generic function A generic function
B Arguments
B Result
This function returns a list of the metho ds attached to the
method Amethod
generic function The order of the metho ds in this list is
unde ned It is an error to mo dify this list
B Result
A list of classes de ning the domain of a metho d
B generic function method lookup function
function
B method function function
B Arguments
generic function A generic function
B Arguments
method Amethod
B Result
A function
B Result
B Remarks
This function returns a function which implements the
metho d The returned function which is called when method
This function returns a function which when applied to the
is called either by calling the generic function with appro
arguments given to the generic function returns a sorted list
priate arguments through a call next method orby using
of applicable metho ds The order of the metho ds in this list
call method A metho d metaob ject itself cannot b e applied
is determined by compute method lookup function
or called as a function
B generic function discriminating function
B method generic function function
function
B Arguments
B Arguments
generic function A generic function
method Amethod
Programming Language EuLisp version
B Result
B compute predicate method
This function returns the generic function to which method
is attached if method is not attached to a generic function
it returns
B Sp ecialized Arguments
B Class Initialization
class class Aclass
B initialize method
B Result
Computes and returns a function of one argument which
B Sp ecialized Arguments
returns true when applied to direct or indirect instances of
class and false otherwise
class class A class
initlist list A list of initializa tion options as fol
lows
B compute constructor generic function
name symbol Name of the class b eing initiali zed
B Generic Arguments
direct superclasses list List of direct sup erclasses
class class Aclass
direct slot descriptions list List of direct slot
sp eci cations
parameters list The argumentlistofthefunction
b eing created
direct initargs list List of direct initargs
B Result
B Result
The initializ ed class
Computes and returns a constructor function for class
B Remarks
The initializ atio n of a class takes place as follows
B compute constructor method
a Check compatibili ty of direct sup erclasses
B Sp ecialized Arguments
b Perform the logical inheritance computations of
class class Aclass
class precedence list
parameters list The argumentlistofthefunction
initargs
b eing created
slot descriptions
c Compute new slot accessors and ensure all new and
B Result
inherited accessors to work correctly on instances of the
Computes and returns a constructor function which returns
new class
a new instance of class
d Make the results accessible by class readers
The basic call structure is laid out in Figure B
B allocate generic function
Note that compute initargs is called by the default
initialize metho d with all direct initargs as the second
B Generic Arguments
argument those sp eci ed as slot option and those sp eci ed
as class option
class class Aclass
initlist list A list of initializa tion arguments
B compute predicate generic function
B Result
B Generic Arguments
An instance of the rst argument
class class A class
B Remarks
B Result
Computes and returns a function of one argument whichis Creates an instance of the rst argument Users may de ne
a predicate function for class new metho ds for new metaclasses
Programming Language EuLisp version
compatible superclasses p cl direct superclasses boolean
compatible superclass p cl superclass boolean
compute class precedence list cl direct superclasses cl
compute inherited initargs cl direct superclasses initarg
compute initargs cl direct initargs inherited initargs initarg
compute inherited slot descriptions cl direct superclasses sd
compute slot descriptions cl slot specs inherited sds sd
either
compute defined slot description cl slot spec sd
compute defined slot description class cl slot spec sd class
or
compute specialized slot description cl inherited sds slot spec sd
compute specialized slot description class
cl inherited sds slot spec sd class
compute instance size cl e ective sds integer
compute and ensure slot accessors cl e ective sds inherited sds sd
compute slot reader cl sd e ective sds function
compute slot writer cl sd e ective sds function
ensure slot reader cl sd e ective sds reader function
compute primitive reader using slot description
sd cl e ective sds function
compute primitive reader using class cl sd e ective sds function
ensure slot writer cl sd e ective sds writer function
iption compute primitive writer using slot descr
sd cl e ective sds function
compute primitive writer using class cl sd e ective sds function
Figure B Initialization Call Structure
reader function A slot reader function
B allocate method
writer function A slot writer function
B Sp ecialized Arguments
B Result
class class A class
The initialize d slot description
initlist list A list of initial izati on arguments
B Generic Function Initialization
B Result
B initialize method
An instance of the rst argument
B Sp ecialized Arguments
B Remarks
gf generic function A generic function
The default metho d creates a new uninitial i zed instance of
the rst argument The initlist is not used bythisallocate
initlist list A list of initial iza tion options as fol
metho d
lows
name symbol The name of the generic function
B Slot Description Initialization
domain list List of argument classes
B initialize method
method class class Class of attached metho ds
B Sp ecialized Arguments
method method description A metho d to b e attached
This option may b e sp eci ed more than once
slot description slot description A slot descrip
tion
B Result
initlist list A list of initial izati on options as fol
The initialize d generic function
lows
name symbol The name of the slot
B Remarks
initfunction function A function
This metho d initiali zes and returns the generic function
The sp eci ed metho ds are attached to the generic func
initarg symbol A symbol tion by add method and its slots are initial ized from
Programming Language EuLisp version
B Result the information passed in initlist and from the re
sults of calling compute method lookup function and
Returns the result of calling compatible superclass p on
compute discriminating function on the generic function
class and the rst elementofthedirect superclasses single
Note that these two functions may not b e called during the
inheritance assumption
call to initialize and that they may b e called several times
for the generic function
B compatible superclass p generic function
The basic call structure is add method gf method gf
compute method lookup function gf domain function
compute discriminating function gf domain lookup fn methods
B Generic Arguments
function
subclass class A class
superclass class A p otential direct sup erclass
B Metho d Initialization
B initialize method
B Result
Returns t if subclass is compatible with superclass otherwise
B Sp ecialized Arguments
method method A metho d
B compatible superclass p method
initlist list A list of initializa tion options as fol
lows
B Sp ecialized Arguments
domain list The list of argument classes
subclass class A class
function fn A function created with
method function lambda
superclass class A p otential direct sup erclass
generic function gf A generic function
B Result
Returns t if the class of the rst argument is a sub class of
B Result
the class of the second argument otherwise
This metho d returns the initial ized metho d metaob ject
method If the generic function option is supplied If the implementation wishes to restrict the instantiation tree
add method is called to install the new metho d in the see intro duction to B this metho d should return false if
generic function superclass is metaclass
B Inheritance Proto col
B compatible superclass p method
B compatible superclasses p generic function
B Sp ecialized Arguments
B Generic Arguments
subclass class A class
class class A class
superclass abstract class A p otential direct su
p erclass
direct superclasses list A list of p otential direct
sup erclasses of class
B Result
Always returns t
B Result
Returns t if class is compatible with direct superclasses oth
erwise
B compatible superclass p method
B Sp ecialized Arguments
B compatible superclasses p method
subclass abstract class A class
B Sp ecialized Arguments
superclass class A p otential direct sup erclass
class class A class
B Result
direct superclasses list A list of p otential direct
sup erclasses
Always returns
Programming Language EuLisp version
B Result
B compatible superclass p method
Computes and returns the list of e ective slot descriptions
of class
B Sp ecialized Arguments
B
See also compute inherited slot descriptions
subclass abstract class A class
superclass abstract class Apotential direct su
p erclass
B compute slot descriptions method
B Result
B Sp ecialized Arguments
Always returns t
class class Class b eing de ned
slot specs list List of direct slot sp eci cations
B compute class precedence list generic function
inherited slot description lists list A list of lists
in fact one list in single inheritance of inherited slot de
B Generic Arguments
scriptions
class class Class b eing de ned
B Result
direct superclasses list List of direct sup erclasses
A list of e ective slot descriptions
B Result
B Remarks
Computes and returns a list of classes which represents the
The default metho d computes two sublists
linearized inheritance hierarchyofclass and the given list
of direct sup erclasses b eginning with class and ending with
a Calling
object
compute specialized slot description with the three
arguments i class ii each inherited slot description as
a singleton list iii the slot spec corresp onding byhaving
the same name to the slot description if it exists other
B compute class precedence list method
wise giving a list of the sp ecialized slot descriptions
b Calling compute defined slot description with
B Sp ecialized Arguments
the three arguments i class ii each slot speci cation
whichdoesnothav e a corresp onding byhaving the same
class class Class b eing de ned
name inherited slot description
direct superclasses list List of direct sup erclasses
The metho d returns the concatenation of these two lists as
its result The order of elements in the list is signi cant
B Result
All sp ecialized slot descriptions have the same p osition as
in the e ective slot descriptions list of the direct sup erclass
A list of classes
due to the single inheritance The slot accessors computed
later may rely on this assumption minimizing the number of
metho ds to one for all sub classes and minimizing the access
B Remarks
time to an indexed reference
This metho d can b e considered to return a cons of class
and the class precedence list of the rst elementofdirect
superclasses single inheritance assumption If no direct
B
superclasses has b een supplied the result is the list of two
See also compute specialized slot description
elements class and object
compute defined slot description
compute and ensure slot accessors
B compute slot descriptions generic function
B compute initargs generic function
B Generic Arguments
B Generic Arguments
class class Class b eing de ned
class class Class b eing de ned
direct slot speci cations list A list of direct slot
sp eci cation
initargs list List of direct initargs
inherited slot descriptions list A list of lists of in
inherited initarg lists list A list of lists of inher
herited slot descriptions
ited initargs
Programming Language EuLisp version
B Result B Result
List of symb ols
List of lists of inherited slot descriptions
B Remarks
B Remarks
Computes and returns all legal initargs for class
The result of the default metho d is a list of one element a
list of e ective slot descriptions of the rst elementofthe
second argument single inheritance assumption Its result
B See also compute inherited initargs
is used by compute slot descriptions as an argument
B compute initargs method
B compute inherited initargs generic function
B Sp ecialized Arguments
B Generic Arguments
class class Class b eing de ned
class class Class b eing de ned
initargs list List of direct initargs
direct superclasses list List of direct sup erclasses
inherited initarg lists list A list of lists of inher
ited initargs
B Result
List of lists of symb ols
B Result
List of symb ols
B Remarks
Computes and returns a list of lists of initargs Its result is
B Remarks
used by compute initargs as an argument
This metho d app ends the second argument with the rst
element of the third argument single inheritance assump
B See also compute initargs
tion removes duplicates and returns the result Note
that compute initargs is called by the default initialize
metho d with all direct initargs as the second argument those
sp eci ed as slot option and those sp eci ed as class option
B compute inherited initargs method
B Sp ecialized Arguments
B compute inherited slot descriptions
generic function
class class Class b eing de ned
B Generic Arguments
direct superclasses list List of direct sup erclasses
class class Class b eing de ned
B Result
direct superclasses list List of direct sup erclasses
List of lists of symb ols
B Result
B Remarks
List of lists of inherited slot descriptions
The result of the default metho d contains one list of legal
initargs of the rst element of the second argument single
inheritance assumption
B Remarks
Computes and returns a list of lists of e ective slot descrip
tions
B compute defined slot description
generic function
B See also compute slot descriptions
B Generic Arguments
B compute inherited slot descriptions method
class class Class b eing de ned
slot spec list Canonicaliz ed slot sp eci cation
B Sp ecialized Arguments
class class Class b eing de ned
B Result
direct superclasses list List of direct sup erclasses
Slot description
Programming Language EuLisp version
B Result B Remarks
The class local slot description
Computes and returns a new e ective slot description It
is called by compute slot descriptions on each slot sp ec
i cation which has no corresp onding inherited slot descrip
B Remarks
tions
This metho d just returns the class
local slot description
B
See also compute defined slot description class
B compute specialized slot description
generic function
B compute defined slot description method
B Generic Arguments
B Sp ecialized Arguments
class class Class b eing de ned
class class Class b eing de ned
inherited slot descriptions list List of inherited
slot spec list Canonicalized slot sp eci cation
slot descriptions each of the same name as the slot b e
ing de ned
B Result
slot spec list Canonicalized slot sp eci cation or
Slot description
B Result
B Remarks
Slot description
Computes and returns a new e ective slot descrip
tion The class of the result is determined by calling
compute defined slot description class
B Remarks
Computes and returns a new e ective slot description It is
B
called by compute slot descriptions on the class each list
See also compute defined slot description class of inherited slots with the same name and with the sp ecial
ising slot sp eci cation list or if no one is sp eci ed with
the same name
B compute defined slot description class
generic function
B
See also compute specialized slot description class
B Generic Arguments
B compute specialized slot description
class class Class b eing de ned
method
slot spec list Canonicalized slot sp eci cation
B Sp ecialized Arguments
B Result
class class Class b eing de ned
Slot description class
inherited slot descriptions list List of inherited
slot descriptions
B Remarks
Determines and returns the slot description class corresp ond
slot spec list Canonicalized slot sp eci cation or
ing to class and slot spec
B See also compute defined slot description
B Result
Slot description
B compute defined slot description class
B Remarks
method
Computes and returns a new e ective slot descrip
tion The class of the result is determined by calling
B Sp ecialized Arguments
compute specialized slot description class
class class Class b eing de ned
B
slot spec list Canonicalized slot sp eci cation
See also compute specialized slot description class
Programming Language EuLisp version
slot description is b ound to the sp eci ed identi er Thus if
a reader writer option is sp eci ed more than once the same
B compute specialized slot description class
ob ject is b ound to all the identi ers If the accessor slot
generic function
option is sp eci ed the anonymous writer will b e installed as
the setter of the reader Sp ecialized slot descriptions refer
B Generic Arguments to the same ob jects as those in the sup erclasses single in
heritance makes that p ossible Since the readers writers are
class class Class b eing de ned el to add generic it is p ossible for a sub class at the meta lev
new metho ds for inherited slot description s in order to make
the readers writers applicable on instances of the sub class
inherited slot descriptions list List of inherited
A new metho d might b e necessary if the sub classes havea
slot descriptions
di erent instance allo cation or if the slot p ositions cannot
be kept the same as in the sup erclass in multiple inheri
slot spec list Canonicalize d slot sp eci cation or
tance extensions This can b e done during the initializa tion
computations
B Result
Slot description class
B compute and ensure slot accessors
generic function
B Remarks
B Generic Arguments
Determines and returns the slot description class corresp ond
ing to i the class b eing de ned ii the inherited slot de
scriptions b eing sp ecialized iii the sp ecializi ng information
class class Class b eing de ned
in slot spec
slot descriptions list List of e ective slot descrip
tions
B
See also compute specialized slot description
inherited slot descriptions list List of lists of in
herited slot descriptions
B compute specialized slot description class
B Result method
List of e ective slot descriptions
B Sp ecialized Arguments
B Remarks
class class Class b eing de ned
Computes new accessors or ensures that inherited accessors
inherited slot descriptions list List of inherited
work correctly for each e ective slot description
slot descriptions
slot spec list Canonicalize d slot sp eci cation or
B compute and ensure slot accessors method
B Sp ecialized Arguments
B Result
The class local slot description
class class Class b eing de ned
slot descriptions list List of e ective slot descrip
B Remarks
tions
This metho d just returns the class
local slot description
inherited slot descriptions list List of lists of in
herited slot descriptions
B Slot Access Proto col
B Result
The slot access proto col is de ned via accessors readers and
List of e ective slot descriptions
writers only There is no primitive like CLOS s slot value
The accessors are generic for standard classes since they
havetowork on sub classes and should do the applicabil i ty
B Remarks
checkanyway The key idea is that the discriminati on on
For each slot description in slot descriptions the default
slot descriptions and classes is p erformed once at class de
metho d checks if it is a new slot description and not an
nition time rather than again and again at slot access time
inherited one If the slot description is new
Each slot description has exactly one reader and one writer
a calls compute slot reader to compute a new slot as anonymous ob jects If a reader writer slot option is sp eci
reader and stores the result in the slot description ed in a class de nition the anonymous reader writer of that
Programming Language EuLisp version
b calls compute slot writer to compute a new slot slot descriptions list List of e ective slot descrip
writer and stores the result in the slot description tions
Otherwise it assumes that the inherited values remain valid
B Result
Finally for every slot description new or inherited
Function
it ensures the reader and writer work correctly on in
stances of class by means of ensure slot reader and
ensure slot writer
B Remarks
Computes and returns a new slot writer applicable to in
B compute slot reader generic function
stances of class and anyvalue to b e stored as the new slot
value corresp onding to slot description The third argument
can b e used in order to compute the logical slot p osition
B Generic Arguments
class class Class
B compute slot writer method
slot description slot description Slot
description
B Sp ecialized Arguments
slot description list list List of e ective slot de
scriptions
class class Class
slot description slot description Slot
B Result
description
Function
slot descriptions list List of e ective slot descrip
tions
B Remarks
Computes and returns a new slot reader applicabl e to in
stances of class returning the slot value corresp onding to
B Result
slot description The third argument can b e used in order to
compute the logical slot p osition
Generic function
B compute slot reader method
B Remarks
The default metho d returns a new generic function of two
arguments without any metho ds Its domain is class
B Sp ecialized Arguments
object
class class Class
slot description slot description Slot
B ensure slot reader generic function
description
slot descriptions list List of e ective slot descrip
B Generic Arguments
tions
class class Class
B Result
slot description slot description Slot
Generic function
description
slot descriptions list List of e ective slot descrip
B Remarks
tions
The default metho d returns a new generic function of one
argument without any metho ds Its domain is class
reader function The slot reader
B compute slot writer generic function
B Result
Function
B Generic Arguments
class class Class
B Remarks
slot description slot description Slot Ensures function correctly fetches the value of the slot from
description instances of class
Programming Language EuLisp version
slot description slot description Slot
description
B ensure slot reader method
slot description list list List of e ectiveslotde
B Sp ecialized Arguments
scriptions
class class Class
writer generic function The slot writer
slot description slot description Slot
description
B Result
Generic function
slot descriptions list List of e ective slot descrip
tions
B Remarks
reader generic function The slot reader
The default metho d checks if there is a metho d in the
generic function If not creates and adds a new one oth
erwise it assumes that the existing metho d works correctly
B Result
The domain of the new metho d is class object and the
Generic function
function is
method function lambda obj class
B Remarks
new value object
The default metho d checks if there is a metho d in the
primitive writer obj new value
generic function If not it creates and adds a new one oth
erwise it assumes that the existing metho d works correctly
compute primitive writer using slot description is
The domain of the new metho d is class and the function is
called by ensure slot writer metho d to compute the prim
itive writer used in the function of the new created writer
method function lambda object class metho d
primitive reader object
compute primitive reader using slot description is
B compute primitive reader using slot description
called by ensure slot reader metho d to compute the prim
generic function
itive reader used in the function of the new created reader
metho d
B Generic Arguments
slot description slot description Slot
B ensure slot writer generic function
description
class class Class
B Generic Arguments
slot descriptions list List of e ective slot descrip
class class Class
tions
slot description slot description Slot
description
B Result
slot descriptions list List of e ective slot descrip
Function
tions
writer function The slot writer
B Remarks
Computes and returns a function which returns a slot value
when applied to an instance of class
B Result
Function
B compute primitive reader using slot description
method
B Remarks
Ensures function correctly up dates the value of the slot in
B Sp ecialized Arguments
instances of class
slot description slot description Slot
description
B ensure slot writer method
class class Class
B Sp ecialized Arguments
slot descriptions list List of e ective slot descrip
tions
class class Class
Programming Language EuLisp version
B Result B Result
Function
Function
B Remarks
B Remarks
Computes and returns a function which stores a new slot
Calls compute primitive reader using class This is the
value when applied on an instance of class and a new value
default metho d
B compute primitive reader using class
B compute primitive writer using slot description
generic function
method
B Sp ecialized Arguments
B Generic Arguments
slot description slot description Slot
class class Class
description
slot description slot description Slot
class class Class
description
slot descriptions list List of e ective slot descrip
slot descriptions list List of e ective slot descrip
tions
tions
B Result
B Result
Function
Function
B Remarks
B Remarks
Calls compute primitive writer using class This is the
Computes and returns a function which returns the slot value
default metho d
when applied to an instance of class
B compute primitive writer using class
B compute primitive reader using class
generic function
method
B Generic Arguments
B Sp ecialized Arguments
class class Class
class class Class
slot description slot description Slot
slot description slot description Slot
description
description
slot descriptions list List of e ective slot descrip
slot descriptions list List of e ective slot descrip
tions
tions
B Result
B Result
Function
Function
B Remarks
B Remarks
Computes and returns a function which stores the new slot
The default metho d returns a function of one argument
value when applied on an instance of class and new value
B compute primitive writer using slot description
B compute primitive reader using class
generic function
method
B Generic Arguments
B Sp ecialized Arguments
slot description slot description Slot
class class Class
description
slot description slot description Slot
class class Class
description
slot descriptions list List of e ective slot descrip
slot descriptions list List of e ective slot descrip
tions
tions
Programming Language EuLisp version
domain list A list of classes which span the do B Result
main
Function
lookup fn function The metho d lo okup function
B Remarks
methods list Alistofmethodsattached to the
The default metho d returns a function of two arguments
generic function
B Metho d Lo okup and Generic Dispatch
B Result
A function
B compute method lookup function
generic function
B Remarks
This generic function computes and returns a function which
B Generic Arguments
is called whenever the generic function is called The re
turned function controls the generic dispatch Users mayde
gf generic function A generic function
ne metho ds on this function for new generic function classes
to implement non default dispatch strategies
domain list A list of classes whichcover the do
main
B compute discriminating function method
B Result
A function
B Sp ecialized Arguments
gf generic function A generic function
B Remarks
Computes and returns a function which will b e called at
domain list A list of classes which span the do
least once for each domain to select and sort the applicabl e
main
metho ds by the default dispatchmechanism New meth
ods may b e de ned for this function to implement di erent
lookup fn function The metho d lo okup function
metho d lo okup strategies Although only one metho d lo okup
function generating metho d is provided by the system each
methods list Alistofmethodsattached to the
generic function has its own sp eci c lo okup function which
generic function
mayvary from generic function to generic function
B Result
A function
B compute method lookup function method
B Remarks
B Sp ecialized Arguments
This metho d computes and returns a function which is called
gf generic function A generic function
whenever the generic function is called This default metho d
implements the standard dispatch strategy The generic
domain list A list of classes whichcover the do
function s metho ds are sorted using the function returned
main
by compute method lookup function and the rst is called
as if by call method passing the others as the list of next
metho ds Note that call method need not b e directly called
B Result
A function
B add method generic function
B Remarks
B Generic Arguments
Computes and returns a function which will b e called at least
once for each domain to select and sort the applicable meth
gf generic function A generic function
ods by the default dispatchmechanism It is not de ned
whether each generic function mayhaveitsown lo okup func
method method A metho d to b e attached to the
tion
generic function
B compute discriminating function
B Result
generic function
This generic function adds method to the generic function
gf This metho d will then b e taken into account when gf
B Generic Arguments is called with appropriate arguments It returns the generic
function gf New metho ds may b e de ned on this generic
gf generic function A generic function function for new generic function and metho d classes
Programming Language EuLisp version
B LowLevel Allo cation Primitives B Remarks
In contrast to CLOS add method do es not remove a metho d
This mo dule provides primitives which are necessary to im
with the same domain as the metho d b eing added Instead
plement new allo cation metho ds p ortably However they
a noncontinuable error is signalled
should b e de ned in suchaway that ob jects cannot b e de
stroyed unintentionall y In consequence it is an error to use
primitive class of primitive ref and their setters on
B add method method
ob jects not created by primitive allocate
B Sp ecialized Arguments
B primitive allocate function
gf generic function A generic function
method method A metho d to b e attached
B Arguments
class A class
B Result
The generic function
size An integer
B Remarks
B Result
This metho d checks that the domain classes of the
An instance of the rst argument
metho d are sub classes of those of the generic function
and that the metho d is an instance of the generic func
tion s metho d class If not signals an error condition
incompatible method and gf It also checks if there B Remarks
is a metho d with the same domain already attached to
This function returns a new instance of the rst ar
the generic function If so a noncontinuabl e error is sig
gument which has a vector like structure of length
naled condition methods exists If no error o ccurs
size The comp onents of the new instance can b e ac
the metho d is added to the generic function Dep ending
cessed using primitive ref and up dated using setter
on particular optimizations of the generic dispatch adding
primitive ref Itisintended to b e used in new allocate
a metho d may cause some up dating computations e g
metho ds de ned for new metaclasses
by calling compute metho d lo okup functio n and compute
discriminatin g functi on
B primitive class of function
B Arguments
object An ob ject created by primitive allocate
B Result
A class
B Remarks
This function returns the class of an ob ject It is similar to
class of whichhasade nedbehaviour on any ob ject It is
an error to use primitive class of on ob jects whichwere
not created by primitive allocate
B setter primitive class of setter
B Arguments
object An ob ject created by primitive allocate
class A class
B Result
The class
Programming Language EuLisp version
B Dynamic Binding B Remarks
This function supp orts p ortable implementations of
B dynamic special form
a dynamic classi catio n like change class in CLOS
b automatic instance up dating of rede ned classes
B Syntax
dynamic form
B primitive ref function
dynamic identifier
B Arguments
B Arguments
object An ob ject created by primitive allocate
identi er A symb ol naming a dynamic binding
index The index of a comp onent
B Result
B Result
An ob ject
The value of closest dynamic binding of identi er is returned
If no visible binding exists an error is signaled condition
unbound dynamic variable
B Remarks
Returns the value of the ob jects comp onent corresp onding
to the supplied index It is an error if index is outside the
B dynamic setq special form
index range of object This function is intended to b e used
when de ning new kinds of accessors for new metaclasses
B Syntax
B setter primitive ref function
dynamic setq form
dynamic setq identifier form
B Arguments
object An ob ject created by primitive allocate
B Arguments
index The index of a comp onent
identi er Asymb ol naming a dynamic binding to b e
value The new value which can b e any ob ject
up dated
form An expression whose value will b e stored in the
B Result
dynamic binding of identi er
The new value
B Result
B Remarks
The value of form
Stores and returns the new value as the ob jects comp onent
corresp onding to the supplied index It is an error if index is
outside the index range of object This function is intended
B Remarks
to b e used when de ning new kinds of accessors for new
The form is evaluated and the result is stored in the closest
metaclasses
dynamic binding of identi er If no visible binding exists an
error is signaled condition unbound dynamic variable
B unbound dynamic variable execution condition
B Initializati on Options
symbol symbol A symb ol naming the unb ound dy
namic variable
B Remarks
Signalled by dynamic or dynamic setq if the given dynamic
variable has no visible dynamic binding
Programming Language EuLisp version
a reconsideration of the de ned mo del Another unpleasant as
p ect of the current mo del is that it is not clear how to address
B dynamic let special form
the issue of imp orting or hiding dynamic variables they are in
every sense global which con icts with the principle of mo dule
abstraction A mo del in which a separate top dynamic environ
B Syntax
ment is asso ciated with each mo dule is under consideration for a
later version of the de nition
dynamic let form
dynamic let
binding
B dynamic multiply defined execution condition
form
B Initializati on Options
B Arguments
symbol symbol Asymb ol naming the dynamic variable
which has already b een de ned
binding A list of binding sp eci ers
body A sequence of forms
B Remarks
Signalled by defvar if the named dynamic variable already
B Result
exists
The sequence of formsisevaluated in order returning the
value of the last one as the result of the dynamic let form
B Exit Extensions
B Remarks
B catch macro
A binding sp eci er is either an identi er or a two element
list of an identi er and an initiali zi ng form All the initial
B Syntax
izing forms are evaluated from left to right in the current
environment and the new bindings for the symb ols named
by the identi ers are created in the dynamic environmentto
catch macro
hold the results These bindings have dynamic scop e and
catch tag form
dynamic extent Each form in body is evaluated in order in
tag
the environment extended by the ab ove bindings The result
symbol A
of evaluating the last form in body is returned as the result
of dynamic let
B Remarks
B defvar de ning form
The catch op erator is similar to block except that the scop e
of the name tag of the exit function is dynamic The catch
tag must b e a symbol b ecause it is used as a dynamic variable
B Syntax
to create a dynamically scop ed binding of tag to the contin
uation of the catch form The continuation can b e invoked
defvar form anywhere within the dynamic extentofthecatch form by
defvar identifier expression
using throw The forms are evaluated in sequence and the
value of the last one is returned as the value of the catch
form The rewrite rules for catch are
B Arguments
catch Is an error
catch tag progn tag
identi er A symb ol naming a top dynamic binding con
catch tag form let cc tmp
taining the value of form
dynamic let tag tmp
form
form The form whose value will b e stored in the top
dynamic binding of identi er
Exiting from a catch by whatever means causes the restora
tion of the lexical environment and dynamic environment
B Remarks
that existed b efore the catch was entered The ab ove rewrite
The value of form is stored as the top dynamic value
for catch causes the variable tmp to b e shadowed This is
of the symb ol named by identi er The binding created
an artifact of the ab ove presentation only and a conforming
by defvar is mutable An error is signaled condition
pro cessor must not shadowanyvariables that could o ccur in
dynamic multiply defined on pro cessing this form more
the b o dy of catch in this way
than once for the same identi er
NOTE The problems engendered by cross mo dule reference
necessitated by a single top dynamic environment are leading to B See also throw
Programming Language EuLisp version
defgeneric form
B throw macro
defgeneric
gf name
gf lambda list
B Syntax
level init option
throw macro
throw tag form
defmethod form
defmethod gfname
method init option B
specialized lambda list
form
B Remarks
In throw the tag names the continuation of the catch from
which to return throw is the invo cation of the continuation
defvar form
of the catch named tag Theform is evaluated and the value
defvar identifier expression
are returned as the value of the catch named by variable The
tag ia a symb ol b ecause it used to access the current dynamic
binding of the symb ol which is where the continuation is
B Syntax of Level expressions
b ound The rewrite rules for throw are
dynamic form
dynamic identifier
throw Is an error
throw tag dynamic tag
throw tag form dynamic tag form
dynamic setq form
dynamic setq identifier form
B See also catch
dynamic let form
dynamic let
B Summary of Level Expressions and Def
binding
initions
form
This section gives the syntax of all level expressions and
de nitions together Any pro ductions unde ned here app ear
generic lambda form
elsewhere in the de nition sp eci cally the syntax of most
generic lambda gf lambda list
expressions and de nitions is given in the section de ning
level init option
level
level init option
class class name
method class class name
B Syntax of Level de ning forms
method level method description
identifier level expression
level init option
level module form
level method description
level expression
method init option
level module form
specialized lambda list
form
method init option
defclass form
class class name
defclass
identifier level expression
class name
superclass list
defclass slot descriptionlist
method lambda form
defclass class option
method lambda
superclass list
method init option B
superclass name
specialized lambda list
defclass slot description list
form
defclass slot description
defclass slot option
initform level expression
identifier level expression
catch macro
defstruct slot option
catch tag form
defclass class option
tag
class class name
symbol A
identifier level expression
defstruct class option
throw macro
throw tag form
Programming Language EuLisp version
References Slade S The T Programming Language a Dialect
of Lisp Prentice Hall
Alb erga C N Bosman Clark C Mikelsons M
Steele Jr G L Common Lisp the Language Digital
Van Deusen M and Padget J A Exp erience with an
Press Second edition Digital Press
Uncommon Lisp In Pro ceedings of ACM Sym
p osium on Lisp and Functional Programming ACM
Stoyan H et al Towards a Lisp Standard In Pro
Press New York Also available as IBM
ceedings of Europ ean Conference on Arti cial In
Research Rep ort RC
telligence
Bobrow D G DeMichiel L G Gabriel R P
Teitelman W The Interlisp Reference Manual Xe Keene S E Kiczales G and Mo on D A Common
Lisp Ob ject System Sp eci cation SIGPLAN Notices
roxPalo Alto ResearchCenter
Septemb er
Bretthauer H and Kopp J The Meta Class
System MCS A Portable Ob ject System for Common
Lisp Do cumentation Arb eitspapiere der GMD
Gesellschaft fur Mathematik und Datenverarb eitung
GMD Sankt Augustin July
Chailloux J Devin M and Hullot J M LELISP
APortable and E cient Lisp System In Pro ceedings
of ACM Symp osium on Lisp and Functional Pro
gramming ACM Press New York
Chailloux J Devin M Dup ont F Hullot J M
Serp ette B and Vuillemin J Le Lisp de l INRIA
Version Manuel de r ef erence INRIA Ro cquen
court
Clinger W and Rees J A editors The Revised
Rep ort on Scheme SIGPLAN Notices Decem
b er
Cointe P Metaclasses are First Class the Ob jVlisp
mo del In Pro ceedings of OOPSLA ACM Press
Decemb er published as SIGPLAN No
tices Vol No
Hudak P and Wadler P editors Rep ort on
the Functional Programming Language Haskell SIG
PLAN Notices May
Lang K J and Pearlmutter B A Oaklisp An
Ob ject Oriented Dialect of Scheme Lisp and Symb olic
Computation June
MacQueen D Mo dules for Standard ML In Pro
ceedings of ACM Symp osium on Lisp and Func
tional Programming ACM Press New York
Milner R et al Standard ML Technical Rep ort
Lab oratory for the Foundations of Computer Science
University of Edinburgh
Padget J A et al Desiderata for the Standard
isation of Lisp In Pro ceedings of ACM Sym
p osium on Lisp and Functional Programming ACM
Press New York
Pitman K M An Error System for Common Lisp
ISO WG do cumentN
Rees J A The T Manual Technical Rep ort Yale
University
Shalit A Dylan an ob ject oriented dynamic lan
guage Apple Computer Inc
Programming Language EuLisp version
Class Index
character character
char file stream stream
class name
condition condition
cons list
double float double
fixed precision integer fpint
float oat
integer integer
local slot description level
lock lo ck
null list
number numb er
object level
slot description level
stream stream
string string
string stream stream
structure level
symbol symbol
table table
thread thread
vector vector
Programming Language EuLisp version
Condition Index
a condition
arithmetic condition numb er
cannot update setter level
cannot update setter level
collection condition collection
conversion condition collection
division by zero numb er
domain condition elementary functions
dynamic multiply defined level
end of stream stream
environment condition condition
execution condition condition
inappropriate stream position stream
d gf level incompatible method an
incompatible method domain level
invalid operator level
method domain clash level
method exists level
no applicable method convert
no converter convert
non congruent lambda lists level
no next method level
no setter level
range condition elementary functions
scan mismatch formatted io
telos condition level
thread already started thread
thread condition thread
unbound dynamic variable level
wrong condition class condition
wrong thread continuation threads
Programming Language EuLisp version
ConstantIndex
fpi fpint
least negative double float double
least positive double float double
maximum vector index vector
most negative double float double
most negative fixed precision integer fpint
most positive double float double
most positive fixed precision integer fpint
nil level
pi elementary functions
t level
ticks per second event
Programming Language EuLisp version
Function Index
number primitive ref level
stream number prin
print stream
number
scan formatted io number
setter level
compare
setter car list compare
setter cdr list number
setter converter convert abs number
setter element collection a function
setter primitive class of level allocate level
setter primitive ref level apply level
signal condition apply method level
signum number apply method function level
slot description initfunction level atom list
slot description name level call method level
slot description slot reader level
call method function level
slot description slot writer level car list
standard error stream stream
cdr list
standard input stream stream cerror condition
standard output stream stream
characterp character
stringp string class initargs level
symbol exists p symb ol
class of level
symbol nam e symb ol class precedence list level
symbolp symbol
level class slot descriptions
clear table table tablep table
threadp thread
conditionp condition
thread reschedule thread
cons list
thread start thread
consp list
thread value thread
convert convert
unlock lo ck
converter convert
vectorp vector
current thread thread
write stream
double float p double
end of stream p stream
eq compare
eql compare
error condition
fixed precision integer p fpint
floatp oat
format formatted io
gcd number
generic function discriminating function level
generic function domain level
generic function method class level
generic function method loo kup function level
generic function methods level
gensym symb ol
integerp integer
lcm number
list list
lock lo ck
lockp lo ck
make level
max compare
method domain level
method function level
method generic function level
min compare
negativep numb er
newline stream
null list
numberp numb er
oddp integer
open stream
positivep numb er
primitive allocate level
primitive class of level
Programming Language EuLisp version
Macro Index
and level
block level
catch level
cond level
defmethod level
defmethod level
generic lambda level
generic lambda level
let level
let level
method function lambda level
method lambda level
or level
quasiquote syntax
return from level
throw level
Programming Language EuLisp version
Generic Function Index
accumulate collection generic prin stream
generic write stream accumulate collection
initialize level
acos elementary functions
input stream add method level
log elementary functions
a generic
log elementary functions allocate level
map collection anyp collection
member collection asin elementary functions
negate number as lowercase character
output stream as uppercase character
pow elementary functions atan elementary functions
read line stream atan elementary functions
reverse collection binary numb er
round oat binary numb er
sequencep collection binary numb er
setter stream position stream
binary numb er
shallow copy copy binary compare
sin elementary functions
binary compare
sinh elementary functions binary numb er
size collection
binary gcd numb er
sqrt elementary functions binary lcm numb er
streamp stream
binary mod numb er
stream position stream ceiling oat
tan elementary functions
character stream p stream
tanh elementary functions close stream
truncate oat
collectionp collection
uninput stream
compatible superclasse s p level
wait event
compatible superclass p level
zerop numb er
compute and ensure slot accessors level
compute class precedence list level
compute constructor level
compute defined slot description level
compute defined slot description class level
compute discriminating function level
compute inherited initargs level
compute inherited slot desc riptions level
compute initargs level
compute method lookup function level
compute predicate level
compute primitive reader using class level
compute primitive reader using slot description
level
compute primitive writer using class level
compute primitive writer using slot description
level
s level compute slot description
compute slot reader level
compute slot writer level
compute specialized slot description level
compute specialized slot description class level
concatenate collection
cos elementary functions
cosh elementary functions
deep copy copy
do collection
element collection
emptyp collection
ensure slot reader level
ensure slot writer level
equal compare
evenp integer
exp elementary functions
file stream p stream
fill collection
floor oat
flush stream
Programming Language EuLisp version
Metho d Index
converter vector collection acos double
cos double add method level
cosh double a generic
deep copy copy allocate level
deep copy copy asin double
deep copy list as lowercase character
deep copy string as lowercase string
deep copy vector as uppercase character
ensure slot reader level as uppercase string
ensure slot writer level atan double
equal character atan double
equal compare binary double
equal double binary fpint
equal fpint binary double
equal list binary fpint
equal string binary double
equal vector binary fpint
evenp fpint binary double
exp double binary fpint
floor double binary character
generic prin character binary double
generic prin double binary fpint
generic prin fpint binary string
generic prin list binary double
generic prin list binary fpint
generic prin string binary fpint
generic prin symb ol binary gcd fpint
generic prin vector binary lcm fpint
generic write character ceiling double
generic write double compatible superclasses p level
generic write fpin compatible superclass p level t
generic write list compatible superclass p level
generic write list compatible superclass p level
generic write string compatible superclass p level
generic write symbol compute and ensure slot accessors level
generic write vector compute class precedence list level
initialize condition compute constructor level
initialize level
compute defined slot description level
initialize level compute defined slot description class level
initialize level compute discriminating function level
initialize level compute inherited initargs level
initialize level compute inherited slot descriptions level
input stream compute initargs level
log double compute method lookup function level
log double compute predicate level
mod double compute primitive reader using class level
mod fpint compute primitive reader using class level
negate double compute primitive reader using slot description
negate fpint level
ription output stream compute primitive writer using slot desc
pow double
level
compute slot descriptions level round double
compute slot reader level shallow copy copy
compute slot writer level shallow copy copy
compute specialized slot description level shallow copy list
compute specialized slot description class level shallow copy string
shallow copy vector
converter double float fpint sin double
converter fixed precision integer double sinh double
converter list collection sqrt double
converter string collection tan double
converter string double tanh double
converter string fpint truncate double
converter string stream uninput stream
converter string sym b ol wait thread
converter symbol string zerop double
converter table collection zerop fpint
Programming Language EuLisp version
General Index
base
arbitrary base literals
limitation on input converter double float
binary literals converter fixed precision integer
binary converter list
binary converter string
binary converter symbol
binary gcd converter table
binary lcm converter vector
binary mod setter car
binary setter cdr
binary setter converter
binary setter element
binary setter primitive class of
dynamicall y scop ed setter primitive ref
mo dule setter stream position
of mo dule names
top dynamic
block
see also let cc
b o olean
call method char file stream
call method function character
call next method class name
car condition
case sensitivity cons
catch double float
cdr fixed precision integer
ceiling float
integer cerror
local slot description character
lock character
null character extension glyph
number mo dule
object character stream p
slot description characterp
stream class
string stream primitive
string self instantiated
structure class initargs
symbol class of
table class precedence list
thread riptions class slot desc
vector clear table
CLOS
a function close
a generic co ercion
a special form collection
abs alignment
accumulate mo dule
accumulate collection con di tion
acos collectionp
add method comment
allocate comment begin glyph
and Common Lisp Error System
anyp mo dule
apply compatible superclass p
apply method compatible superclasses p
apply method function compliance
as lowercase compute and ensure slot accessors
as uppercase compute class precedence list
asin compute constructor
assignment compute defined slot description
atan compute defined slot description class
compute discriminating atan function
atom compute inherited initargs
backquoting compute inherited slot descriptions
Programming Language EuLisp version
do compute initargs
double oat compute method lookup function
mo dule compute predicate
double float p compute primitive reader using class
dynamic compute primitive reader using slot description
dynamic environment compute primitive writer using class
dynamic error compute primitive writer using slot description
dynamic let compute slot descriptions
dynamic setq compute slot reader
element er compute slot writ
elementary functions compute specialized slot description
emptyp compute specialized slot description class
end of stream p concatenate
ensure slot reader cond
ensure slot writer condition
environmental error continuable
eq non continuable
implementation de n ed b ehaviour conditionp
eql con guration
equal conformance
error level
error level
can b e signalled conforming pro cessor
dynamic conforming program
environmental conformity clause
handler least negative double precision oat
signalled least p ositive double precision oat
static maximum vector index
evenp most negative double precision oat
exp most negative xed precision integer
extension most p ositive double precision oat
oating p oint most p ositive xed precision integer
integer cons
list consp
null empty list constant
pair de ned
string literal
vector continuation
external representation see also prin and write conventions
false convert
file stream p mo dule
fill converter
xed precision integer cos
mo dule cosh
fixed precision integer p current thread
oat deep copy
float defclass
floatp defcondition
floor defconstant
flush defgeneric
format de ning form
formatted io defclass
function defcondition
calling defconstant
reader defgeneric
standard function de o cal
writer defstruct
function call defvar
gcd deflocal
generic arithmetic defmacro
generic function defmethod
lamb da list defmodule
generic function discriminating function defstruct
generic function domain defun
generic function method class defvar
generic function method lookup function direct instance
generic function methods direct sub class
direct sup erclass generic lambda
Programming Language EuLisp version
thread generic prin
vector generic write
character gensym
collection Haskell
compare hexadecimal literals
condition identi er
convert de nition of
copy p eculiar identi ers
double oat syntax
elementary functions if
eulisp level implementation de ned
oat b ehaviour of eq
formatted io least negative double precision oat
fpi least p ositive double precision oat
integer maximum vector index
lo ck mo dule directives
numb er most negative double precision oat
stream most negative xed precision integer
string most p ositive double precision oat
symb ol most p ositive xed precision integer
table time units p er second
thread unhandled conditions
vector indirect instance
lexical environment indirect sub class
list single
list inheritance graph
mo dule inherited slot description
literal init list
arbitrary base initarg
binary initform
character initfunction
hexadecimal initializ ation
mo di cation of initialize
o ctal inner dynamic
quotation inner lexical
k lo c input
lock instance
lockp direct
log indirect
log instantiation graph
macro integer
de nition by defmacro integer
macro expansion see also syntax integerp
macros see also syntax labels
make lambda
map lcm
max LeLisp
MCS let
member let
metaclass let cc
metho d see also block and return from
bindings level
sp eci city character
metho d sp eci city char file stream
method domain double float
method function float
method function lambda fixed precision integer
method generic function integer
method lambda lock
MicroCeyx null
min object
mod cons
mo dule stream
directives string
environments string stream
exp ort structure
exp ose symbol
imp ort table
Programming Language EuLisp version
name bindings slot description
syntax slot option
multi metho d slot sp eci cation
negate slot description initfunction
negativep slot description name
new instance slot description slot reader
newline slot description slot writer
next method p sp ecial form
null a sp ecial form
null call next metho d
numb er dynamic
co ercion dynamic let
mo dule dynamic setq
numberp if
Oaklisp lab els
ob ject lamb da
syntax let cc
Ob jVLisp next metho d p
o ctal literals progn
oddp quote
open setq
or unwind protect
output with handler
pair sp ecialize
pair sp ecialize on
positivep sqrt
pow Standard ML
primitive allocate standard mo dule
primitive class of ror stream standard er
primitive ref standard input stream
prin standard output stream
print static error
constants stream
symb ols mo dule
pro cessor stream position
gensym names streamp
progn string
quasiquotation string
quasiquote escaping in
abbreviation with mo dule
quote string escap e glyph
abbreviation with stringp
range condition sub class
read line direct
re ective indirect
return from sup erclass
see also let cc direct
symbol reverse
symb ol round
mo dule scan
symbol exists p in labels expressions
symbol name of dynamic let bindings
symbolp of lambda bindings
syntax of let cc binding
self instantiated class
character sequencep
constant setq
defmacro setter
defmo dule setter function
defun shallow copy
oat signal
function call signum
generic function lambda list simple function
identi er sin
integer single inheritance
pair sinh
string size
symb ol slot
Programming Language EuLisp version
unquote
unquote splicin g
vector
syntax expansion
T
table
mo dule
tablep
tan
tanh
thread
thread reschedule
thread start
thread value
threadp
throw
top dynamic
top lexical
true
truncate
uninput
unlock
unquote
abbreviation with
unquote splicing
abbreviation to
unwind protect
vector
vector
vectorp
wait
de nition of
with handler
write
zerop
Common Lisp
level
level
libraries
InterLISP
LE LISP
LISP VM