Programming Language Eulisp
Version
Programming Language EuLisp version
Contents Page
Foreword
Intro duction
Scop e
Normative References
Conformance De nitions
Error De nitions
Compliance
Conventions
Layout and Typ ography
Meta language
Naming
De nitions
Syntax
Whitespace and Comments
Mo dules
Imp orts
Syntax
Exp orts
De nitions and Expressions
Mo dule Pro cessing
Mo dule De nition
defmodule
Ob jects
Creating and Initializin g Ob jects
initialize
initialize
Accessing Slots
External Representation
generic prin
generic write
Classes and Slot Desciptions
Inheritance
Slot Descriptions
System De ned Classes
De ning Classes
defstruct
defclass
slot description
Creating Ob jects
make ii
Programming Language EuLisp version
telos condition
Generic Functions and Metho ds
De ning Generic Functions and Metho ds
defgeneric
defmethod
no applicable method
incompatible method signature
non congruent lambda lists
Sp ecializi ng Metho ds
call next method
no next method
next method p
Threads and Semaphores
Threads
thread
threadp
thread reschedule
current thread
thread start
thread value
wait
thread condition
wrong thread
old thread
generic prin
generic write
Semaphores
semaphore
semaphorep
open semaphore
close semaphore
generic prin
generic write
Conditions
condition
execution condition
environment condition
Condition Handling
signal
wrong condition class
with handler
Conditions
conditionp
condition message
initialize instance
error
cerror
defcondition
Expressions De nitions and Control Forms
Atomic Expressions
constant
defconstant
symbol
deflocal
Literal Expressions
quote
Functions Application De nition
lambda
function call
invalid operator
defmacro
defun
apply
bad apply argument iii
Programming Language EuLisp version
Assignments
setq
setter
no setter
cannot update setter
Conditional Expressions
if
cond
and
or
Variable Binding and Sequences
let cc
labels
let
let
progn
unwind protect
Waiting on Events
wait
ticks per second
Quasiquotation Expressions
quasiquote
unquote
unquote splicing
improper unquote splice
Summary of Level Expressions and De nitions
Annexes
A Level Mo dule Library
A Characters
A character
A character
A characterp
A converter integer
A equal
A copy
A generic prin
A generic write
A generic write
A Collections
A empty p
A size
A member
A do
A map
A reduce
A reduce
A fill
A catenate
A filter
A Comparing Ob jects
A eq
A
A eql
A equal
A equal
A Conversion
A convert
A conversion condition
A no converter
A converter
A setter converter
A Copying Ob jects
A copy
A copy
A Double Precision Floats
A double float iv
Programming Language EuLisp version
A double float
A double float p
A most positive double float
A least positive double float
A least negative double float
A most negative double float
A truncate
A truncate
A round
A round
A floor
A floor
A ceiling
A ceiling
A converter string
A converter single precision integer
A integer conversion overflow
A copy
A generic prin
A generic write
A Elementary Functions
A pi
A sin
A cos
A tan
A acos
A asin
A atan
A atan
A exp
A log
A log
A log
A sqrt
A sqrt
A sqrt
A expt
A sinh
A cosh
A tanh
A asinh
A acosh
A atanh
A Formatted IO
A scan mismatch
A scan
A format
A The empty list
A
A null
A null
A length
A generic prin
A generic write
A Numb ers
A number
A numberp
A integer
A integerp
A float
A floatp
A arithmetic condition
A equal
A
A
A
A
A v
Programming Language EuLisp version
A
A
A
A max
A min
A gcd
A lcm
A abs
A zerop
A signum
A positivep
A negativep
A binary plus
A binary difference
A negate
A binary times
A binary divide
A binary lt
A binary gcd
A binary lcm
A Pairs and Lists
A pair
A pair
A consp
A atom
A cons
A car
A cdr
A setter car
A setter cdr
A converter string
A not a character
A converter string
A equal
A copy
A list
A length
A copy alist
A copy list
A copy tree
A generic prin
A generic write
A Single Precision Integers
A single precision integer
A single precision integer
A single precision integer p
A evenp
A evenp
A oddp
A oddp
A division by zero
A quotient
A quotient
A remainder
A remainder
A modulo
A modulo
A most positive single precision integer
A most negative single precision integer
A converter character
A no such character
A converter string
A converter double float
A copy
A generic prin
A generic write
A Streams
A stream vi
Programming Language EuLisp version
A file stream
A input stream
A io stream
A ouput stream
A file streamp
A stream condition
A syntax error
A input stream p
A output stream p
A io stream p
A character stream p
A binary stream p
A open
A open
A open p
A open p
A close
A close
A write unit
A write unit
A write unit
A write
A generic write
A prin
A generic prin
A read unit
A read unit
A read
A generic read
A generic read
A peek unit
A peek unit
A flush
A flush
A wait
A Strings
A string
A string
A stringp
A string ref
A setter string ref
A converter pair
A equal
A copy
A length
A string lt
A string slice
A string append
A generic prin
A generic write
A Symb ols
A symbol
A symbol
A symbolp
A gensym
A symbol name
A symbol exists p
A generic prin
A generic write
A generic write
A Tables
A table
A tablep
A table ref
A setter table ref
A table delete
A generic prin
A generic write vii
Programming Language EuLisp version
A Vectors
A vector
A vector
A vectorp
A length
A vector ref
A setter vector ref
A make initialized vector
A maximum vector index
A converter pair
A equal
A copy
A generic prin
A generic write
B Programming Language EuLisp Level
B Classes and Ob jects
B defclass
B Generic Functions
B defgeneric
B defmethod
B generic lambda
B generic labels
B Re ection on Ob jects
B class of
B Re ection on Classes and Slot Descriptions
B slot description
B local slot description
B class name
B class precedence list
B class slot descriptions
B class initargs
B slot description name
B slot description initfunction
B slot description slot reader
B slot description slot writer
B De ning Metaclasses
B defmetaclass
B Initializi ng Classes
B initialize
B Initializi ng Slot Descriptions
B initialize
B Inheritance Proto col
B compatible superclasses p
B compatible superclasses p
B compatible superclass p
B compatible superclass p
B compatible superclass p
B compatible superclass p
B compute class precedence list
B compute class precedence list
B compute slot descriptions
B compute slot descriptions
B compute initargs
B compute initargs
B compute inherited slot descriptions
B compute inherited slot descriptions
B compute inherited initargs
B compute inherited initargs
B compute defined slot description
B compute defined slot description
B compute defined slot description class
B compute defined slot description class
B compute specialized slot description
B compute specialized slot description
B compute specialized slot description class
B compute specialized slot description class
B Slot Access Proto col viii
Programming Language EuLisp version
B compute and ensure slot accessors
B compute and ensure slot accessors
B compute slot reader
B compute slot reader
B compute slot writer
B compute slot writer
B ensure slot reader
B ensure slot reader
B ensure slot writer
B ensure slot writer
B compute primitive reader using slot description
B compute primitive reader using slot description
B compute primitive reader using class
B compute primitive reader using class
B compute primitive writer using slot description
B compute primitive writer using slot description
B compute primitive writer using class
B compute primitive reader using class
B Predicates and Constructors
B compute predicate
B compute predicate
B compute constructor
B compute constructor
B Instance Allo cation
B allocate
B allocate
B Low Level Allo cation Primitives
B primitive allocate
B primitive class of
B setter primitive class of
B primitive ref
B setter primitive ref
B Re ection on Generic Functions and Metho ds
B Introsp ection
B generic function name
B generic function domain
B generic function range
B generic function method class
B generic function methods
B generic function method lookup function
B generic function discriminating function
B method domain
B method range
B method function
B method generic function
B Sp ecial forms or macros
B method function lambda
B call method
B apply method
B Initializi ng Generic Functions and Metho ds
B initialize
B initialize
B Metho d Lo okup and Generic Dispatch
B compute method lookup function
B compute method lookup function
B compute discriminating function
B compute discriminating function
B Extending Generic Functions by New Metho ds
B add method
B add method
B remove method
B remove method
B Dynamic Binding
B dynamic
B dynamic setq
B unbound dynamic variable
B dynamic let
B defvar ix
Programming Language EuLisp version
B dynamic multiply defined
B Conditional Extensions
B when
B unless
B Exit Extensions
B block
B return from
B catch
B throw
B Summary of Level Expressions and De nitions
Bibliography
Indexes
Function Index
Macro Index
Generic Function Index
Metho d Index
Condition Index
Constant Index
General Index
Figures
Example of imp ort and exp ort directives
Level initial class hierarchy
State diagram for threads
Level initial condition class hierarchy
A Level numb er class hierarchy and co ercion chart
B Initializati on Call Structure
Tables
Mo dules comprising level
Minimal character set
Mo dule syntax
generic prin output syntax
generic write output syntax
defstruct syntax
defclass syntax level
defgeneric syntax level
Quasiquote Syntax
Expressions and De nitions level
A Sp ecial Character Syntax
A Character Syntax
A Metho ds for double precision oats
A Floating Point Syntax x
Programming Language EuLisp version
A expt result classes
A Pair and List Syntax
A Metho ds for single precision integers
A Integer Syntax
A Sign combination in modulo
A Initial stream class hiearchy
A String escap e digrams
A Examples of string literals
A String Syntax
A Identi er Symb ol Syntax
A Vector Syntax
B defclass syntax level
B defgeneric syntax level
B Slot Description Metaob ject Classes
B Metaob ject Classes
B Generic Function Metaob ject Classes
B Expressions and De nitions level xi
COMMITTEE DRAFT Programming Language EuLisp version
Programming Language EuLisp version
they started and the authors would like to thank all those
who have help ed in the development of EULISP
Initially funding for the EULISP group came from individ u
als institutions or companies but since the Commis
sion of the Europ ean Communities CEC as the EULISP
Technical Interest Group TIG also called the EULISP
committee supp orted by DG XI I I has provided the as
sistance without which this e ort would have faded away
In addition the EULISP group is grateful for the sup
p ort of British Council in France Alliance programme
British Council in Spain Acciones Integradas programme
British Council in Germany Academic Research Collab
oration programme British Standards Institute Centre
d Estudis Avan cats de Blanes CSIC Departament de Llen
guatges i Sistemes Inform atics LSI Universitat Polit ecnica
Foreword
de Catalunya Gesellschaft fur Mathematik und Datenver
arb eitung GMD ILOG S A Insiders GmbH Institut Na
The EULISP group rst met in Septemb er at IRCAM in
tional de Recherche en Informatique et en Automatique IN
Paris to discuss the need for a common Europ ean dialect of
RIA Institut de Recherche et de Co ordination Acoustique
Lisp Subsequent meetings formulated the view of EULISP
Musique IRCAM Rank Xerox France Science and Engi
that was presented at the ACM Conference on Lisp
neering Research Council Siemens AG University of Bath
and Functional Programming held at MIT Cambridge Mas
University of Technology Delft University of Edinburgh
sachussetts Padget et al and at the Europ ean Confer
Universit at Erlangen Universit e Paris VI LITP
ence on Arti cial Intelligence ECAI held in Brighton
Sussex Stoyan et al Since then progress has not
The following p eople in alphab etical order have con
b een steady but happ ening as various p eople had su cient
tributed in various ways to the evolution of the language
time and energy to develop part of the language Conse
Giusepp e Attardi Javier B ejar Russell Bradford Harry
quently although the vision of the language has in the most
Bretthauer Peter Broadb ery Christopher Burdorf J er ome
part b een shared over this p erio d only certain parts were
Chailloux Thomas Christaller Je Dalton Klaus D a ler
turned into physical descriptions and implementation s For
Harley Davis David DeRoure John Fitch Richard Gabriel
a nine month p erio d starting in January through the
Brigitte Glas Nicolas Graub e Dieter Kolb Jurgen Kopp
supp ort of INRIA it b ecame p ossible to start writing this
Pascal Kuczynski Antonio Moreno Eugen Neidl Pierre Par
do cument the EULISP de nition Since then a airs have
quier Keith Playford Willem van der Po el Christian Quein
returned to their previous state but with the evolution of
nec Enric Sesa Herb ert Stoyan and Richard Tobin
the implementations of EULISP and the background of the
foundations laid by the INRIA supp orted work there is con
The editors wish particularly to acknowledge the work of
vergence to a consistent and practical de nition
Harley Davis on the rst version of the description of the
ob ject system and of Harry Bretthauer on the second version
The acknowledgements for this rep ort fall into three cate
gories intellectual p ersonal and nancial
Julian Padget jap maths bath ac uk
Scho ol of Mathematical Sciences
The ancestors of EULISP in alphab etical order are Com
University of Bath
mon Lisp Steele InterLISP Teitelman LE
Bath Avon BA AY UK
LISP Chailloux et al LISP VM Alb erga et al
Scheme Clinger Rees and T Rees et al
Slade There has also b een some feedback from a lan
Greg Nuyens nuyens ilog fr
guage which has b een in uenced by EuLisp namely Dylan
ILOG SA
Shalit Thus the authors of this rep ort are pleased to
Avenue Galli eni
acknowledge b oth the authors of the manuals and de nitions
Gentilly CEDEX FRANCE
of the ab ove languages and the many who have dissected and
extended those languages in individ ual pap ers The various
pap ers on Standard ML Milner et al and the draft
rep ort on Haskell Hudak Wadler et al have also pro
editors
vided much useful input
The writing of this rep ort has at various stages b een sup
p orted by Bull S A Ecole Polytechnique LIX ILOG S A
Institut National de Recherche en Informatique et en Au
tomatique INRIA University of Bath and Universit e Paris
VI LITP The authors gratefully acknowledge this sup
p ort Many p eople from Europ ean Community countries
have attended and contributed to EULISP meetings since
Programming Language EuLisp version
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 Bo
brow et al Ob jVLisp Cointe Oaklisp Lang
Pearlmutter and MicroCeyx Chailloux et al
The greatest debt of TELOS is to CLOS from which it takes
the ideas of generic functions and multi metho ds In addi
tion most of the terminology the names and format of the
user level macros and the names of many of the functions in
the internal proto col are inspired by CLOS From Ob jVLisp
TELOS takes the principle of a re ective architecture which
emphasizes the p ower of metaclasses as an implementation
strategy From Oaklisp TELOS takes the idea of anonymous
classes Finally from MicroCeyx TELOS takes the idea of
a small highly e cient kernel tightly integrated with the
Intro duction
rest of the language In TELOS this integration is achieved
through the total merging of typ es with classes and message
The purp ose of this do cument is to de ne the programming
passing through normal function application Classes are
language EULISP EULISP is a dialect of Lisp and as such
rst class values The class structure integrates the primitive
owes much to the great b o dy of work that has b een done
classes describing fundamental datatyp es the de ned classes
on language design in the name of Lisp over the last thirty
and user de ned classes The function class of given an
years EULISP is the outcome of e orts on the part of many
ob ject returns the class of which it is a direct instance
p eople in countries of the Europ ean Community since
The guiding principles of the language are simplici ty expres
Mo dules and classes are the buildin g blo cks of b oth the
siveness completeness orthogonality of constructs formal
EULISP language and of application s written in EULISP The
de nition and e cient implementation
mo dule system exists to limit access to items by name That
is mo dules allow for hidden de nitions Each mo dule de nes
EULISP do es not claim any particular Lisp dialect as its
a fresh empty lexical environment This fresh environment
closest relative although parts of it were in uenced by fea
is the top lexical environment of that mo dule A de ning
tures found in Common Lisp InterLISP LE LISP LISP VM
form creates a new binding in the top lexical environment of
Scheme and T
the lexical environment in which it is evaluated
EULISP b oth intro duces new ideas and takes from these
Continuations are rst class in EULISP but they are not as
Lisps It also extends or simpli es their ideas as necessary
general as in Scheme They are weaker b ecause they can
It takes a class system but extends the notion by integrat
only b e used within the dynamic extent of their creation
ing the primitive typ es classes with user de ned classes
That also implies they can only b e used once These weaker
It has a condition system It intro duces a mo dule mecha
continuations are suitable for controlling simple non lo cal
nism for information hiding and separate compilation and it
exits and form the basis of the condition system of hand lers
has rst class continuations But this is not the place for a
Functions to o are rst class comprising the environment
detailed language comparison That can b e drawn from the
of de nition the closure of the de nition and an expression
rest of this rep ort However it is imp ortant to stress that the
as describ ed by Landin in ISWIM Landin
distinguishi ng features of EULISP are the integration of the
classical Lisp typ e system and the ob ject system into a sin
Dynamically scop ed bindings can b e created in EULISP but
gle class hierarchy the complementary abstraction facilities
their use is much more restricted than in most Lisps up to
provided by the class and the mo dule mechanism and su
now except Scheme EULISP enforces a strong distinction
p ort for concurrent execution EULISP inherits from Scheme
b etween lexical bindings and dynamic bindings by requir
the prop erties of static scoping a single lexical environment
ing the use of a sp ecial form called dynamic let for their
for all variables and the uniform treatment of op erator and
creation and two other sp ecial forms called dynamic and
op erands
dynamic setq for access and up date resp ectively
NOTE version Changes b etween this version and
are further improvements to the parallel pro cessing mo del and
Multiple control threads can b e created in EULISP and or
the addition and revision of some of the thread op erations a ma
derly access to data shared b etween more than one control
jor rewrite of input output functions and the asso ciated stream
thread can b e mediated by means of semaphores
classes a ma jor rewrite of telos to account for the revised meta
ob ject proto col a ma jor reorganisation of the do cument to re ect
b etter the structure of the language and hop efully to make it
Language Structure
easier to grasp the essentials of the design on rst reading
The EULISP de nition comprises the following items
Overview
Level comprises all the level functions macros
and sp ecial forms which is this do cument minus annex B
The op erator and the op erands of forms are treated in a uni
The class system can b e extended by user de ned struc
form manner Here EULISP continues the tradition exempli
ture classes and generic functions
ed in Scheme T LISP VM and Cambridge LISP Fitch
Norman In common with other LISP like languages
function parameters are passed by value and in common Level extends level with the functions macros
with Scheme and some other Lisps functions themselves are and sp ecial forms de ned in annex B The class system
rst class values can b e extended by user de ned classes and metaclasses
Programming Language EuLisp version
The implementation of level is not necessarily written or b The minimal requirements of a con guration that is
writable as a conforming level program capable of supp orting an implementation of an EULISP
pro cessor
Level is yet to b e elab orated
c The metho d of preparation of an EULISP program for
execution or the metho d of activation of this EULISP pro
A level function is a generic function de ned by this re
gram once prepared
p ort to b e part of a conforming pro cessor for level A func
tion de ned in terms of level op erations is an example of a
d The metho d of rep orting errors warnings or excep
level application Note that apart from new sp ecial forms
tions
the functionality for all level functions can b e de ned in
terms of level op erations Thus any level function is a
e The typ ographical representation of an EULISP pro
level application The same constructive de nition applies
gram for human reading
to level functions b eing level applications
To clarify certain instances of the use of English in this do c
Much of the functionality of EULISP is de ned in terms of
ument the following de nitions are provided
mo dules These mo dules might b e available and used at
any level but certain mo dules are required at certain levels
must a verbal form used to intro duce a required prop
Whenever a mo dule dep ends on the op erations available a
erty All conforming pro cessors must satisfy the prop erty
given level that dep endency will b e sp eci ed
should A verbal form used to intro duce a strongly rec
The main part of this do cument de nes the kernel of level
ommended prop erty Implementers of pro cessors are urged
of EuLisp The annex A de nes all the remaining classes and
but not required to satisfy the prop erty
mo dules which comprise level The de ned name of the
mo dule providing level of EuLisp is level eulisp which
imp orts and re exp orts the mo dules sp eci ed in Table
Normative References
Table Mo dules comprising level
The following standards contain provisions which through
references in this do cument constitute provisions of this def
Mo dule Section
inition At the time of writing the editions indicated were
character A
valid All standards are sub ject to revision and parties mak
collection A
ing use of this de nition are encouraged to apply the most
compare A
recent edition of the standard listed b elow
convert A
copy A
ISO Information processing ISO bit coded char
double A
acter set for information interchange Note this stan
elementary functions A
dard is currently under revision and interested parties should
formatted io A
reference the Draft International Standard version of
null A
ISO IEC
number A
pair A
ISO Data processing vocabulary
semaphore
spint A
ISO TR Information technology Guide
stream A
lines for the preparation of conformity clauses in program
string A
ming language standards
symbol A
table A
ISO TR Information technology Guide
thread
lines for the preparation of programming language standards
vector A
Note this is currently a draft technical report
BS Method of de ning Syntactic metalanguage
Level of EuLisp is de ned in annex B
Conformance De nitions
Scop e
The following terms are general in that they could b e applied
This do cument sp eci es the syntax and semantics of the
to the de nition of any programming language They are
computer programming language EULISP by de ning the re
derived from ISO IEC TR
quirements for a conforming EULISP pro cessor and a con
forming EULISP program the textual represenation of data
and algorithms
con guration Host and target computers any op
erating systems s and software run time system used to
This do cument do es not sp ecify
op erate a language processor
a The size or complexity of an EULISP program that
will exceed the capacity of any sp eci c con guration or conformity clause Statement that is not part of
pro cessor nor the actions to b e taken when those limits the language de nition but that sp eci es requirements for
are exceeded compliance with the language standard
Programming Language EuLisp version
conforming program Program which is written in NOTE The violation of the syntatic or static semantic re
quirements is not an error but an error might b e signaled by the
the language de ned by the language standard and which
program p erforming the analysis of the EULISP program
ob eys all the conformity clauses for programs in the language
standard
All errors sp eci ed in this de nition are dynamic unless ex
plicitly stated otherwise
conforming pro cessor Processor which pro cesses
conforming programs and program units and which ob eys all
the conformity clauses for processors in the language stan
Compliance
dard
An EULISP pro cessor can conform at any of the three levels
de ned under Language Structure in the Intro duction Thus
error Incorrect program construct or incorrect
a level conforming pro cessor must supp ort all the basic
functioning of a program as de ned by the language stan
expressions classes and class op erations de ned at level
dard
A level conforming pro cessor must supp ort all the basic
expressions classes class op erations and mo dules de ned at
level A level conforming pro cessor must supp ort all the
extension Facility in the processor that is not sp ec
classes class op erations and all of the mo dules de ned at
i ed in the language standard but that do es not cause any
level
ambiguity or contradiction when added to the language stan
dard
The following two rules govern the conformance of a pro ces
sor at a given level
implementation de ned Sp eci c to the proces
a A conforming processor must correctly pro cess all pro
sor but required by the language standard to b e de ned
grams conforming b oth to the standard at the sp eci ed
and do cumented by the implementer
level and the implementation de ned features of the pro
cessor
pro cessor Compiler translator or interpreter work
ing in combination with a con guration
b A conforming processor should o er a facility to rep ort
the use of an extension which is statically determinable
solely from insp ection of a program without execution
It is also considered desirable that a facility to rep ort the
Error De nitions
use of an extension which is only determinable dynamically
b e o ered
Errors in the languge describ ed in this de nition fall into one
of the following three classes
A level conforming program is one which observes the syn
tax and semantics de ned for level A level conforming
program might not conform at level A strictly conforming
dynamic error An error which is detected during
level program is one that also conforms at level A level
the execution of an EULISP program or which is a violation
conforming program observes the syntax and semantics
of the dynamic semantics of EULISP Dynamic errors have
de ned for level A level conforming program is also a
two classi cation s
level conforming program Hence by extension a level
strictly conforming program is also a level conforming
a Where a conforming processor is required to detect
program
the erroneous situation or b ehaviour and rep ort it This is
signi ed by the phrase an error is signaled The condition
In addition a conforming program at any level must not use
class to b e signaled is sp eci ed Signallin g an error con
any extensions implemented by a language processor but it
sists of identifying the condition class related to the error
can rely on implementation de ned features
and allo cating an instance of it This instance is initial
ized with information dep endent on the condition class A
The do cumentation of a conforming processor must include
conforming EULISP program can rely on the fact that this
condition will b e signaled
a A list of all the implementation de ned de nitions or
values
b Where a conforming processor might or might not de
tect and rep ort up on the error This is signi ed by the
b A list of all the features of the language standard
phrase is an error Such errors should b e detected and
which are dep endent on the processor and not imple
rep orted
mented by this processor due to non supp ort of a partic
ular facility where such non supp ort is p ermitted by the
standard
environmental error An error which is detected
by the con guration supp orting the EULISP pro cessor The
c A list of all the features of the language implemented
pro cessor must signal the corresp onding dynamic error which
by this processor which are extensions to the standard lan
is identi ed and handled as describ ed ab ove
guage
d A statement of conformity giving the complete ref
static error An error which is detected during the
erence of the language standard with which conformity
preparation of a EULISP program for execution such as a
is claimed and if appropriate the level of the language
violation of the syntax or static semantics of EULISP by the
supp orted by this pro cessor
EULISP program under preparation
Programming Language EuLisp version
Conventions this case any new metho ds must resp ect the domain and or
range of the generic function to which they are to b e at
tached The use of a class descriptive name in the context
This section de nes the conventions employed in this do cu
of a generic function de nition de nes the intention of the
ment how de nitions will b e will b e laid out the typ eface
de nition and is not necessarily a p oliced restriction
to b e used the meta language used in descriptions and the
naming conventions A later section contains de nitions
If it is required to indicate rep etition the notation
of the terms used in this do cument
+
expression and expression will b e used for zero or more
and one or more o ccurrences resp ectively The arguments in
Layout and Typ ography
some function descriptions are enclosed in square brackets
graphic representation and This indicates that the
Both layout and fonts are used to help in the description
argument is optional The accompanying text will explain
of EULISP A language element is de ned with its name as
what default values are used
the heading of a clause coupled with its classi catio n for
example
The result class of an op eration except in one case refers
special form name special form
to a primitive or a de ned class describ ed in this de nition
function name function
The exception is for predicates Predicates are de ned to
generic function name generic
return either the empty list written representing the
generic function name method
b o olean value false or any value other than representing
condition name super condition
true Although the class containing this set of values is not
de ned in the language notation is abused for convenience
Thus a sample entry might app ear as
and boolean is de ned for the purp oses of this rep ort to
sample function function
mean that set of values If the true value is a useful value
it is sp eci ed precisely in the description of the function
Arguments
arg An instance of class x
1
Naming
arg An instance of class x
2
Naming conventions are applied in the descriptions of prim
itive and de ned classes as well as in the choice of other
arg An optional argument of class x
3
function names Here is a list of the conventions and some
examples of their use
Result
The result class
name wrapping By convention the initial
bindings of classes have names which b egin with and
end with
Remarks
Some clarifying background to the actions of the function
binary pre x The two argument version of a n
ary argument function There is not always a corresp ondence
Examples
b etween the ro ot and the name of the n ary function for
Some examples of calling the function with certain argu
example binary plus is the two argument generic function
ments and the result that should b e returned
corresp onding to the n ary argument function
See also Cross references to other sections or to
class su x The name of a metaclass of a set of
other individu al relevant language elements
related classes For example function class which is the
metaclass of function generic function and any of their
sub classes and condition class is the class of all conditions
Meta language
The exception is class itself which is the default metaclass
The pre x should describ e the general domain of the classes
The terms used in the following descriptions are de ned in
in question but not necessarily any particular class in the
section
set
A standard function denotes a immutable mo dule binding of
the de ned name All the de nitions in this do cument are
generic pre x The generic version of the func
bindings in some mo dule except for the sp ecial form op era
tion named by the stem
tors which have no bindings anywhere All bindings and all
the sp ecial form op erators can b e renamed
hyphenation Function and class names made up
Frequently a class descriptive name will b e used in the ar
of more than one word are hyphenated for example
gument list of a function description to indicate a restriction
compute primitive reader using slot description
on the domain to which that argument b elongs In the case
of a function it is an error to call it with a value outside
the sp eci ed domain In the case of a generic function the p su x A predicate function is named by a p
domain can b e widened arbitrarily by the de nition of new su x if the function or class name is not hyphenated for
metho ds similarly the range except when the generic func instance consp and is named by a p su x if it is for
tion was de ned with a particular domain and or range In instance compatible superclass p
Programming Language EuLisp version
ref su x For each builtin or de ned class list are determined by the class of the class through methods
there is a eld accessor named class name ref where of the generic function compute class precedence list
appropriate and a corresp onding eld up dator setter
class name ref also where appropriate for example
class option A keyword and its asso ciated value
table ref This convention is broken by historical prece
applying to a class app earing in a class de nition form for
dent for the accessors to slots of pairs which are called car
example the predicate keyword and its value which de nes
and cdr
a predicate function for the class b eing de ned
De nitions
closure The closure of an expression E is the set
of all free variables that o ccur in E
This set of de nitions which will b e used throughout this
do cument is self consistent but might not agree with notions
congruent A constraint on the form of the
accepted in other language de nitions The terms are de ned
in alphab etical rather than dep endency order and where a lamb da list of a metho d which requires it to have the same
numb er of elements as the generic function to which it is to
de nition uses a term de ned elsewhere in this section it
is written in italics Some of the terms de ned here are b e attached
redundant Names in courier font refer to entities de ned
in the language
constant A numb er string character or the
empty list
accessor An accessor is a asso ciation of a reader and
a writer
constructor A constructor is a function which
creates an instance of a particular class
applicable metho d A method is applicabl e for a
particular set of arguments if each element in its signature is
continuation A continuation is a function of one
a superclass of the class of the corresp onding argument
parameter which represents the rest of the program For ev
ery p oint in a program there is the remainder of the program
applicable metho d list An applicable metho d list
coming after that p oint This can b e viewed as a function
is a list of all the methods applicabl e for a particular list of
of one argument awaiting the result of that p oint Such a
arguments to a generic function sorted according to method
function is called a continuation
signature sp eci city
converter function The generic function asso ci
applicable ob ject An applicabl e ob ject is an in
ated with a class the target that is used to pro ject an in
stance of function
stance of another class the source to an instance of the
target
binding A lo cation containing a value
de ning form Any form or any macro ex
pression expanding into a form whose op erator is one
binding form Any form or any macro expression
of defclass defcondition defconstant defgeneric
expanding into a form which causes the creation of inner
deflocal defmacro defmetaclass defstruct defun
dynamic or inner lexical bindings
defvar
b ound variable A variable x is b ound in an ex
direct instance A direct instance of a class class
1
pression E if x o ccurs in the scope of a de ning form which
is any object whose class is class
1
creates inner lexical bindings or of a binding form o ccurring
in E whose variable binding list contains x
direct slot description A class s direct slot de
scriptions are de ned sp eci cally for the class
class A class is an object which describ es the struc
ture and b ehavior of a set of objects which are its instances
A class ob ject contains inheritance information and a set of
direct sub class A class is a direct subclass of
1
slot descriptions which de ne the structure of its instances
class if class is a subclass of class class is not identical
2 1 2 1
A class object is an instance of a metaclass All classes in
to class and there is no other class which is a superclass
2 3
EULISP are subclasses of object and all instances of class
of class and a subclass of class
1 2
are classes
direct sup erclass A direct superclass of a class
class precedence list Each class has a linearized
class is any class for which class is a direct subclass
1 1
list of all its superclasses direct and indirect b eginning
with the class itself and ending with the ro ot of the in
discrimination Generic function applicatio n con heritance graph the class object This list determines
sists of two parts nding a set of methods applicabl e to the the sp eci city of slot and metho d inheritance A class s
given set of arguments and application of the method func class precedence list may b e accessed through the function
tions of those methods The rst part is called discrimination class precedence list The rules used to compute this
Programming Language EuLisp version
or method lookup Generic functions have an asso ciated func inde nite scop e An access constraint such that
tion called the discriminating function which implements the the scope of the variable is unlimited
discriminatio n Users can de ne new classes of generic func
tions which implement discrimination in new ways
indirect instance A indirect instance of a class
class is any object whose class is a subclass of class
1 1
dynamic environment The inner and top dy
namic environment taken together are referred to as the
indirect slot description A slot description is in
dynamic environment
direct for a class if the slot description is de ned for class
1 1
but was originally de ned for another class which is a su
2
perclass of class and incorp orated into class through inher
1 1
dynamic extent A lifetime constraint such that
itance An indirect slot description is also called an inherited
the entity is created on control entering an expression and
slot description
destroyed when control exits the expression Thus the entity
only exists for the time b etween control entering and exiting
the expression
indirect sub class A class is an indirect sub class
1
of class if class is a subclass of class class is not identical
2 1 2 1
to class and there is at least one other class which is a
2 3
dynamic scop e An access constraint such that
superclass of class and a subclass of class
1 2
the scope of the entity is limited to the dynamic extent of
the expression that created the entity
inheritance graph A directed lab elled acyclic
graph whose no des are classes and whose edges are de ned
dynamically closer If a form F is executed in
by the subclass relations b etween the no des This graph has
the dynamic extent of a form F then within the dynamic
a distinguis hed ro ot the class object which is a superclass
extent of F F is dynamicall y closer than F
of every class
extent That lifetime for which an entity exists
inherited slot description See indirect slot de
Extent is constrained to b e either dynamic or inde nite
scription
form One of constant symbol literal function call
initarg A symbol used as a keyword in an initlist
or special form
to mark the value of some slot Used in conjunction with
make and the other object initiali zati on functions to sp ecify
initial slot values An initarg may b e declared for a slot in a
free variable A variable x is free in an expression
class de nition form using the initarg slot option
E if x do es not o ccur in the lexical scope of any de ning which
creates inner lexical bindings or any binding form o ccurring
in E whose variable binding list contains x
initform A form which is evaluated to pro duce a
default initial slot value Initforms are closed in their lexi
cal environments and the resulting closure is called an init
function A function comprises at least an expres
function An initform may b e declared for a slot in a class
sion a set of identi ers which o ccur in the expression called
de nition form using the initform slot option
the parameters and the closure of the expression with re
sp ect to the lexical environment in which it o ccurs less the
parameter identi ers Note this is not a de nition of the
initfunction A function of no arguments whose
class function
result is used as the default value of a slot Initfunctions
capture the lexical environment of an initform declaration in
a class de nition form
generic function Generic functions are functions
for which the method executed dep ends on the class of its
arguments A generic function is de ned in terms of methods
initlist A list of alternating keywords and values
which describ e the action of the generic function for a sp eci c
which describ es some not yet instantiated ob ject Generally
set of argument classes called the metho d s signature
the keywords corresp ond to the initargs of some slot descrip
tion of some class
identi er An identi er is the syntactic represen
tation of a variable
inner dynamic Inner dynamic bindings are cre
ated by dynamic let referenced by dynamic and mo di ed
by dynamic setq Inner dynamic bindings extend and can
improp er list An improp er list is a list whose
shadow the dynamicall y enclosing dynamic environment
nal pair contains something other than the empty list in its
cdr eld
inner lexical Inner lexical bindings are created by
lambda and let cc referenced by variables and mo di ed by
inde nite extent A lifetime constraint such that setq Inner lexical bindings extend and can shadow the
the entity exists for ever In practice this means for as long lexically enclosing lexical environment Note that let cc
as the entity is accessible creates an immutable binding
Programming Language EuLisp version
instance Every object is the instance of some metho d lo okup See discrimination
class An instance thus describ es an object in relation to
its class An instance takes on the structure and b ehavior
metho d sp eci city A signature signature is
1
describ ed by its class An instance can b e either direct or
more sp eci c than another signature if the rst class in
2
indirect
signature is a subclass of the rst class in signature or
1 2
if they are the same the rest of signature is more sp eci c
1
instantiation graph A directed graph whose
than the rest of signature
2
no des are objects and whose edges are de ned by the in
stance relations b etween the objects This graph has only
multi metho d A method which sp ecializes on all
one cycle an edge from class to itself The instantation
its arguments All metho ds in this de nition are multi
graph is a tree and class is the ro ot
metho ds
lexically closer If a form F o ccurs in a form F
new instance A newly allo cated instance which
then any bindings created by F are lexically closer than
is distinct but can b e isomorphic to other instances
those of F
ob ject Any entity that can b e b ound to a
lexical environment The inner and top lexical
variable including entities from outside LISP s memory Ev
environment of a mo dule are together referred to as the lex
ery ob ject is an instance of some class
ical environment except when it is necessary to distinguish
b etween them
prop er list A prop er list is a list whose nal pair
contains the empty list in its cdr eld or is just the empty
lexical scop e An access constraint such that the
list
scope of the entity is limited to the textual region of the form
creating the entity See also lexical ly closer and shadow
reader A reader is a function of one argument
which returns the value of a particular slot in instances of a
literal An ob ject created by use of the quote op
particular class
erator
macro A macro is a function A macro is distin
re ective A system which can examine and mo d
guished from a function by when it is used macro functions
ify its own state is said to b e re ective EULISP is re ective to
are only used during the syntax expansion of mo dules to
the extent that it has explicit class ob jects and metaclasses
transform expressions
and user extensible op erations up on them
macro expression A form whose op erator names
scop e That part of the extent in which a given
a macro expansion function
variable is accessible Scop e is constrained to b e lexical dy
namic or inde nite
metaclass A metaclass is a class object whose in
stances are themselves classes All metaclasses in EULISP are
self instantiated class A class which is an in
instances of class which is an instance of itself All meta
stance of itself In EULISP class is the only example of
classes are also subclasses of class class is a metaclass
a self instantiated class
metho d A metho d describ es the action of a
setter function The function asso ciated with the
generic function for a particular list of argument classes
function that accesses a place in an entity which changes the
called the metho d s signature A method is thus said to add
value stored that place
to the b ehavior of each of the classes in its signature Meth
o ds are not functions but objects which contain among other
shadow If two entities are created for which the
information a function representing the metho d s b ehavior
same means of reference is used and either the form creating
one o ccurs lexically in the form creating the other where the
metho d combination The applicabl e metho d
means of reference has lexical scope or the form creating one
list for an argument list determines the next method called
is executed in the dynamic extent of the form creating the
by the sp ecial form call next method for any method in
other where the means of reference has dynamic scope then
the list the next method is simply the method following it in
the outer entity is shadowed by the inner one
the list
signature A signature is a list of classes derived
metho d function A function which implements
from a list of arguments or the list of classes for which a
the b ehavior of a particular method Metho d functions have
method is applicable
sp ecial restrictions which do not apply to all functions their
formal parameter bindings are immutable and the sp ecial
slot A named comp onent of an object which can forms call next method and next method p are only valid
b e accessed using the slot s accessor Each slot of an object within the lexical scop e of a metho d function
Programming Language EuLisp version
is describ ed by a slot description object asso ciated with the All these bindings are immutable deflocal creates a muta
class of the object When we refer to the structure of an ble top lexical binding All such bindings are referenced by
object this usually means its set of slots variables and those made by deflocal are mo di ed by setq
Each mo dule de nes its own distinct top lexical environment
slot description A slot description object de
variable A variable denotes a binding and is a
scrib es a slot in the instances of a class This descrip
means to reference the value stored in the binding
tion includes the slot s name its logical p osition in in
stances and a way to determine its default value A
class s slot descriptions may b e accessed through the func
writer A writer is a function of two arguments
tion class slot descriptions A slot description can b e
which changes the value of a particular slot in instances of a
either direct or indirect
particular class
slot option A keyword 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
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
any form which must b e evaluated in a sp eci c way
sp ecialize A verbal form used to describ e the cre
ation of a more sp eci c version of some entity Normally
applied to classes slot description s and metho ds
sp ecialize on A verbal form used to describ e re
lationship of metho ds and the classes sp eci ed in their sig
natures
sub class The b ehavior and structure de ned by a
class class are inherited by a set of classes which are termed
1
subclasses of class A subclass can b e either direct or indi
1
rect
sup erclass A class is a sup erclass of class i
1 2
class is a sub class of class A superclass can b e either
2 1
direct or indirect
symb ol A symb ol is a data structure often used
to represent an identi er
textual slot description A list of alternating
keywords and values starting with a keyword which rep
resents a not yet created slot description during class initial
isation
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 environ
ment of a mo dule by defclass defcondition defconstant
defgeneric defmacro defmetaclass defstruct and defun
Programming Language EuLisp version
Mo dules Syntax
Case is distinguish ed in each of characters strings and iden
The EULISP mo dule scheme has several in uences the exist
ti ers so that variable name and Variable name are dif
ing Le Lisp implementation the mo del de ned in the func
ferent but where a character is used in a p ositional numb er
tional language Haskell the ML mo dule system MacQueen
representation e g x Ad the case is ignored Thus case
the make environment mo dule mechanism used in C
is also signi cant in this do cument and as will b e observed
Scheme and T s locales
later all the sp ecial form and standard function names are
lower case In this section and throughout this do cument
The mo dule mechanism provides a means of abstraction and
the names for individu al character glyphs are those used in
a means of security for programs in a complementary style to
ISO IEC DIS
that provided by the ob ject system Indeed although ob jects
do supp ort data abstraction they do not supp ort all forms
The minimal character set to supp ort EULISP is de ned in
of information hiding For this reason it is imp ortant to
Table The language as de ned in this do cument uses
provide a mechanism o ering the complete hiding of names
only the characters given in this table Thus left hand sides
A mo dule de nes a mapping b etween a set of names and the
of the pro ductions in this table de ne and name groups of
bindings of those names in the imp orted mo dule Most such
characters which are used later in this de nition digit upper
bindings are immutable The exception are those bindings
lower other special and alphabetic
created by deflocal which may b e mo di ed by the de ning
and imp orting mo dules There are no implicit imp orts into
The syntax of the classes of ob jects that can b e read by
a mo dule and not even the sp ecial forms are available in a
EULISP is de ned in the section of this do cument corresp ond
mo dule that imp orts nothing A mo dule exp orts nothing by
ing to the class character A double float
default
null A pair A spint A
string A symbol A and vector A The
A mo dule de nition creates two new empty lexical
syntax for identi ers corresp onds to that for symb ols
environments the internal and the external top lexical en
vironments of the mo dule All the bindings in the mo dule
b o dy are stored in the internal top lexical along with those
Whitespace and Comments
bindings shared by imp ortation with other mo dules The
external top lexical shares those bindings from the internal
Whitespace characters are space and newline The newline
top lexical that are exp orted and also those of all the exp osed
character is also used to represent end of record for con gu
mo dules mo dules which are exp orted but not imp orted
rations providing such an input mo del thus a reference to
The names of mo dules are b ound in a disjoint binding en
newline in this de nition should also b e read as a reference
vironment which is only accessible via the mo dule de nition
to end of record The only use of whitespace is to improve
form That is to say mo dules are not rst class The rep
the legibil ity of programs for human readers Whitespace
resentation of the mo dule environment is implementation
separates tokens and is only signi cant in a string or when
de ned The b o dy of a mo dule de nition comprises an im
it o ccurs escap ed within an identi er
p ort directive followed by a syntax directive and a sequence
of de nitions expressions and exp ort directives The pro
A comment is intro duced by the comment begin glyph called
cessing of each of these is now discussed in detail
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
Imp orts
the newline Thus a comment is equivalent to whitespace
The imp ort directive is expressed in terms of mo dule names
and the lters except only and rename The syntax of
imp ort sp eci cations is given in Table An import spec
is a sequence of module names and or module directives and
denotes the union of all the names generated by each element
of the sequence
In pro cessing imp ort directives every name should b e
thought of as a pair of module name local name coupled
with some attributes mutable immutable syntax value
Intuitively a namelist of mo dule name lo cal name pairs is
generated by giving the mo dule name and then ltered by
except only and rename In addition all names with a
syntax attribute are ltered out b ecause syntax functions
can have no use at execution time In an imp ort directive
when a namelist has b een ltered the names are regarded as
b eing de ned in the internal top lexical environment of the
mo dule into which they have b een imp orted Should any two
instances of local name have di erent module names then
there is a name clash which is a static error Elements of an
import spec are interpreted as follows
except Filters the names from each module directive
discarding those sp eci ed and keeping all other names
The except directive is convenient when almost all of the
Programming Language EuLisp version
Table Minimal character set
digit j j j j j j j j j
upper A j B j C j D j E j F j G j H j I j J j K j L j M j N j O j P j
Q j R j S j T j U j V j W j X j Y j Z
lower a j b j c j d j e j f j g j h j i j j j k j l j m j n j o j p j
q j r j s j t j u j v j w j x j y j z
other j j j j j j j j j j j j j j j j j j j j j
special j j j j j j j j j
alert j backspace j delete j formfeed j linefeed j new line j return j space j tab j vertical tab
alphabetic upper j lower
names exp orted by a mo dule are required since it is only c If the identi er names a sp ecial form then the form
necessary to name those few that are not wanted to ex sp eci c expansion function is invoked
clude them
d If the form is a list the expansion pro cess is applied
module name All the exp orted names from module
to the op erator and the op erands of the form The result
name
is a form containing the results of the expansion of the
op erator and the op erands in the order corresp onding to
only Filters the names from each module directive
the order of the op erator and the op erands in the original
keeping only those names sp eci ed and discarding all other
form The expansion pro cess is applied to the resulting
names The only directive is convenient when only a few
form
names exp orted by a mo dule are requied since it is only
necessary to name those that are wanted to include them
The result of each step of the expansion pro cess is a form
containing references to the bindings visible from the mo dule
rename Filters the names from each module directive
in which the expansion function is de ned
replacing those with old name by new name Any name
not mentioned in the replacement list is passed unchanged
Note that once a name has b een replaced the new name
is not compared against the replacement list again Thus
Exp orts
a binding can only b e renamed once by a single rename
directive In consequence name exchanges are p ossible
The exp ort directive is expressed either in terms of bindings
names using export or export syntax or mo dule names
using expose The syntax of exp ort sp eci cations is given
Syntax
in Table
The syntax section de nes the expansion functions for the
Pro cessing exp ort directives employs the same mo del as for
b o dy of the mo dule This section comprises an imp ort di
imp orts namely a mo dule name lo cal name pair with the
rective for access to expanders de ned in other mo dules and
same ltering op erations When the namelist has b een l
a sequence of de nitions The imp ort directive is pro cessed
tered the names are added to the set of exp ortations of this
as describ ed ab ove except that all names which do not have
mo dule It is the union of all the exp ort directives in the
a syntax attribute are ltered out The b o dy of the syntax
b o dy of a mo dule de nes the externally visible top lexical
section is expanded according to the syntax environment de
environment of the mo dule Should any two instances of
ned by the imp ort directive of the syntax section All the
local name have di erent module names then there is a name
resulting functions are added to the syntax environment and
clash which is a static error Note that the external top
the b o dy of the mo dule is then expanded according to that
lexical environment might not b e a subset of the internal
environment
top lexical environment b ecause the external one can refer
ence mo dules which have not b een imp orted
NOTE version Currently the semantics of syntax expan
sion are unsatisfactory b ecause expanders are not opaque to the
The sequence of export specs in the mo dule b o dy is treated
user That is to say the resulting expansion can contain references
to bindings imp orted into the syntax mo dule and those mo dules
as the union of all the names generated by each export spec
must also b e imp orted explicitly by the user of the macro using the
It is a static error if any name o ccurs more than once Each
same binding renamings as the syntax mo dule Neither is there a
export spec is interpreted as follows
requirement for hygienic expansion so expander and user b ound
variables may interfere with one another It is intended that the
export Each of the names app earing in the export
next version of this do cument should sp ecify a syntax expansion
form is added to the external top lexical environment of
scheme that is opaque to the user
the mo dule
The basic expansion mechanism examines each form in the
mo dule b o dy applying the following pro cess
export syntax Each of the names app earing in the
export form is added to the external top lexical environ
a If the form is not a list the result is the original form
ment of the mo dule with the syntax attribute set
b If the form is a list and the op erator is an identi er
expose Pro cesses each of the module directives app ear
which is b ound in the syntax environment then the asso
ing in the expose form following the rules for import spec
ciated expansion function is called on a list of the un
and adds the resulting set of names to the external top
evaluated op erands of the form The expansion pro cess
lexical environment of the mo dule
is applied to the resulting form
Programming Language EuLisp version
Figure Example of imp ort and exp ort directives
defmodule example
module import everything from module
except function a module al l but function a from module
only function b module but just function b from module
rename function c function d exchange the names of the bindings of function c and
function d
function d function c module from module
syntax
syntax module al l of the module syntax module
rename syntax a syntax b syntax module rename the binding of syntax a from syntax module to
syntax b
rename syntax c syntax a syntax module now rename syntax c from syntax module as syntax a
expose module export al l of module
except function e module export al l of module except function e
export local definition but just three bindngs from this module
local definition
local definition
De nitions and Expressions cording to the op erators de ned in the syntax environment
constructed from the syntax imp ort directive and the lo cal
de nitions
De nitions in a mo dule only contain unquali ed names
that is local names using the ab ove terminology All top
lexical mo dule bindings are only ever created once and are
Environment Construction All the de ned variables
shared with all mo dules that imp ort the mo dule creating the
are collected and added to the mo dule s top lexical en
bindings Only top lexical bindings created by deflocal are
vironment
mutable and it is an error to mo dify an immutable bind
ing Expressions that is non de ning forms are collected
Exp ort Pro cessing The exp ortations are collected and
and evaluated in order of app earance at the end of the mo d
the set of exp orted names is constructed
ule de nition pro cess when the top lexical environment is
complete The exception to this is the progn form which is
Static Analysis The expanded b o dy of the mo dule is
descended and the forms within it are treated as if the progn
analysed It is a static error if a variable in the b o dy do es
were not present
not have a binding in the top lexical environment
Initializati on The mo dule is initiali zed by evaluating
Mo dule Pro cessing
the forms in the b o dy in the order they app ear
The following steps summarize the mo dule de nition pro
cess
Mo dule De nition
Imp ort Pro cessing Mo dule imp ort clauses either
sp ecify the imp ortation of a mo dule in its entirety or the
selective imp ortation of sp eci ed bindings from a mo dule
defmodule syntax
For each imp ort sp eci cation the originating mo dule must
exist and in the case of selective sp eci cations the named
binding s must b e exp orted from it Each imp ort sp eci
Syntax
cation contributes a set of bindings to the top lexical envi
The syntax of the text of a mo dule is given in Table
ronment of the mo dule b eing de ned Each such binding
is checked for name con ict since no two imp orted names
can b e the same Note that mutually referential mo dules
Arguments
are not p ossible b ecause of the de nition b efore use re
quirement Hence the imp ortation dep endencies form a
module name A symb ol used to name the mo dule
DAG
Syntax Expansion The syntax section sp eci es the import spec An expression sp ecifying the mo dules on
mo dules required for syntax expansion and any lo cally which the execution of this mo dule dep ends and how their
de ned syntax The b o dy of the mo dule is expanded ac exp orts are to b e named for reference in this mo dule
Programming Language EuLisp version
Table Mo dule syntax
import spec module directive
syntax spec j syntax import spec defmacro
export spec export j export syntax j expose
export export name
export syntax export syntax name
expose expose module directive
module directive module name j module lter
module lter except j only j rename
+
except except name module directive
+
only only name module directive
+
rename rename old name new name module directive
module expression export spec j level expression j de nition j progn expression
de nition level de nition
fdefmoduleg
syntax spec An expression sp ecifying the mo dules on Ob jects
which the expansion of this mo dule dep ends and how their
exp orts are to b e named for reference in this mo dule
In EULISP every ob ject in the system has a sp eci c class
Classes themselves are rst class ob jects In this resp ect
module expression A sequence of de nitions expres
EULISP di ers from statically typ ed ob ject oriented lan
sions and exp ort sp eci cations
guages such as C and CEYX The EULISP ob ject system
is called TELOS
Remarks
Programs written using TELOS typically involve the design
of a class hierarchy where each class represents a category of
The defmodule form de nes a mo dule named by module
entities in the problem domain and a protocol which de nes
name and stores a mo dule ob ject in the mo dule binding en
the op erations on the ob jects in the problem domain
vironment under the name module name
A class de nes the structure and b ehavior of its instances
Examples
Structure is the information contained in the class s instances
and behavior is the way in which the instances are treated
An example mo dule de nition with explanatory comments
by the proto col de ned for them
is given in Figure
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
whose b ehavior dep ends on the classes of their arguments
The particular class sp eci c b ehavior is partitioned into sep
arate units called methods A metho d is not a function itself
but is a closed expression which is a comp onent of a generic
function
It may b e p ossible in an implementation to acquire a p ointer
that do es not corresp ond to any EULISP ob ject It is an error
to pass such a p ointer to a function The default domain for
arguments of functions is object
Creating and Initializing Ob jects
Ob jects can b e created calling
constructors prede ned or user de ned or
make the general constructor function
The general constructor make creates a new ob ject calling
allocate and initiali zes it calling initialize allocate
discriminates on the class while initialize discrimina tes
on the new ob ject Both initialize and allocate as well
as more sp eci c constructors are describ ed in more detail
in section The default allocate metho d creates a new
uninitial ized ob ject that is all slots are unb ound The de
fault initialize metho d see b elow is applicabl e to any
ob ject although there are also more sp eci c metho ds for
classes slot descriptors generic functions and metho ds
Programming Language EuLisp version
Table generic prin output syntax
initialize generic function
prin datum prin character j number j prin string j
structure j prin symbol
Generic Arguments
prin character any character
prin string prin string char
object object The ob ject to initiali ze
prin symbol prin string
prin string char any character
initlist list The list of initiali zati on arguments
Result
is no writer for a slot its value cannot b e changed When
users de ne new classes they can sp ecify which readers and
The initialize d ob ject
writers should b e accessible in a mo dule and by which bind
ing Accessor bindings are not exp orted automatically when
Remarks
a class binding is exp orted They can only b e exp orted
explicitly
Initializes an ob ject using the most sp eci c metho d for the
class of the ob ject and returns the initialize d ob ject as the
At the metalevel there is a proto col which allows user de
result
ned metho ds for the computation of sp ecial accessors for
example those checking the typ e of a value when storing a
new one
initialize method
Sp eciali zed Arguments
External Representation
object object The ob ject to initiali ze
generic prin generic function
initlist list The list of initiali zati on arguments
Generic Arguments
Result
object object An ob ject to b e output on stream
The initialize d ob ject
stream stream The stream on which object is to b e
output
Remarks
This is the default metho d attached to initialize This
metho d p erforms the following steps
Result
a Check if the supplied initargs are legal and signal an
The ob ject supplied as the rst argument
error otherwise Legal initargs are those sp eci ed in the
class de nition directly or inherited from a sup erclass Ini
targs may b e slot names or other symb ols
Remarks
b Initialize the slots of the ob ject according to the ini
The individual metho ds for sp eci c classes de ne the for
targ if supplied or according to the initfunction stored
mat of the output The representation pro duced by
in the slot description followed by calling the anonymous
generic prin may b e more convenient for human reading
writer stored in the slot description The initfunction may
but is not guaranteed to by syntactically correct input for a
return unb ound if no initform has b een sp eci ed di
EuLisp pro cessor Sp eci cally generic prin will not out
rectly in the class de nition or none was inherited from a
put escaping information in characters strings or symb ols
sup erclass
This is summarised in the grammar in Table
Legal initargs which do not name a slot are ignored by the
default initialize metho d The default metho d can b e
generic write generic function
sp ecialized by calling call next method from more sp eci c
initialize metho ds
Generic Arguments
See also initialize metho ds for classes slot de
object object An ob ject to b e output on stream
scriptors generic functions and metho ds make allocate
stream stream The stream on which object is to b e
Accessing Slots
output
Ob ject comp onents slots can b e accessed using reader and
writer functions accessors only For system de ned ob ject
Result
classes there are prede ned readers and writers Some of
The ob ject supplied as the rst argument the writers are accessible using the setter function If there
Programming Language EuLisp version
Table generic write output syntax
Classes and Slot Desciptions
A class describ es a set of ob jects called its instances in
datum character j number j string j structure j
the problem domain Classes de ne the structure of their
symbol
instances through a set of slots which each instance contains
structure list j vector
Classes also de ne the b ehavior of their instances through
the metho ds which sp ecialize on them
Remarks
Inheritance is implemented through classes Each class has
The individual metho ds for sp eci c classes de ne the for
a class precedence list a linearized list of all the class s su
mat of the output The representation pro duced by
p erclasses which de nes the classes from which the class
generic write is guaranteed to b e syntactically correct in
inherits structure and b ehavior Slots and metho ds de ned
put for a EuLisp pro cessor and will result in an ob ject equal
for a class will also b e de ned for its sub classes but a sub class
to the original entity The syntax of ob jects output by
may sp ecialize them
generic write is given in Table
In EULISP classes are rst class ob jects and are instances of
some sp eci c class These classes of classes are called meta
classes Extensions such as multiple inheritance supp ort
for the change class functionality of CLOS and p ersistent
ob jects can b e supp orted through metaclasses In addition
metaclasses can provide new kinds of classes with reduced
p ower but increased e ciency the class structure class
is an example
Classes are de ned using the defstruct
defcondition and defclass de ning forms New
metaclasses are de ned using defmetaclass
Inheritance
The structure and b ehaviour de ned for a class is inherited
by all of its sub classes In practice this means that an in
stance of a class will contain all the slots de ned directly in
the class as well as all of those de ned in the class s sup er
classes In addition a metho d sp ecialized on a particular
class will b e applicabl e for direct and indirect instances of
the class
TELOS level provides only single inheritance meaning that
a class can have exactly one sup erclass but inde nitely
many sub classes In fact all classes in the level class in
heritance tree have exactly one sup erclass except the ro ot
class object which has no sup erclass
Metaclasses control the structure and b ehaviour of their in
stances and the representation of their metainstances It
might not b e p ossible to form a sub class link b etween two
classes of di erent metaclasses The meta ob ject proto col
MOP provides means to control compatibil ity b etween
classes with resp ect to the sub class relationhsip
Slot Descriptions
The comp onents of an ob ject are called its slots Each slot of
an ob ject is de ned by its class It is represented by a slot de
scription object which de nes where the slot is to b e stored
how it can b e accessed and its default value At level of
EULISP and ab ove the slot description mechanism is sp ecial
izable and extensible New slot description classes to supp ort
extensions such as the facets found in many knowledge rep
resentation languages multi valued slots typ ed slots and
slots whose values are not stored in the instance Slots
are de ned within a defstruct defcondition or defclass
de ning form New slot description classes are de ned by
defclass
Programming Language EuLisp version
System De ned Classes slot description A list of slot sp eci cations see b e
low comprising either a slot name or a list of a slot name
followed by some slot options
The basic classes of EULISP are elements of the ob ject system
class hierarchy which is shown in Figure Indentation indi
class option A sequence of keys and values see b elow
cates a sub class relationship to the class under which the line
has b een indented for example condition is a sub class
of object and the name following the class is the name
Remarks
of the metaclass for example the class of condition is
condition class The names given here corresp ond to
defstruct creates a new structure class The rst argument
the bindings of names to classes as they are exp orted from
is the name to which the new class will b e b ound The
the level level or level mo dules
second is identi er which names a variable to which the su
p erclass is b ound If superclass is the sup erclass is taken
Figure Level initial class hierarchy
to b e the ro ot structure class structure The list of slot
descriptions is describ ed b elow Finally a class option is a
object class
identi er followed by a corresp onding value which taken
character class
together apply to the class as a whole The syntax of
class class
defstruct is de ned in Table
condition class class
function class class
The slot options are interpreted as follows
number class class
structure class class
initarg symbol The value of this option is a identi er
naming a symb ol which is the name of an argument to b e
condition condition class
supplied in the init option s of a call to make on the new
function function class
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 ed
method class
once for a particular slot The same initarg name may b e
null class
used for several slots in which case they will share the
number number class
same initial value if the initarg is given to make
pair class
initform form The value of this option is a form which
semaphore class
is evaluated as the default value of the slot to b e used if
stream class
string class
no initarg is de ned for the slot or given to a call to make
structure structure class
The form is evaluated in the lexical environment of the call
symbol class
to defstruct and the dynamic environment of the call to
table class
make The form is evaluated each time make is called and
thread class
the default value is called for The order of evaluation of
vector class
the initforms in all the slots is determined by initialize
This option must only b e sp eci ed once for a particular
slot
The ro ot of the instantiatio n hierarchy is the class class
which is an instance of itself The ro ot of the inheritance
reader symbol The value is the identi er of the variable
hierarchy is the class object class de nes the basic
to which the reader function will b e b ound The reader
metho ds for access and mo di cation of ob jects comp onents
function is a means to access the slot The reader function
In this de nition unless otherwise sp eci ed all ob jects de
is a function of one argument which should b e an instance
clared to b e of a certain class may b e indirect instances of
of the new class No writer function is automatically cre
that class Furthermore unless otherwise sp eci ed classes
ated with this option This option can b e sp eci ed more
declared to b e sub classes of other classes may b e indirect
than once for a slot creating several readers It is an error
sub classes
to sp ecify the same reader writer or accessor name for
two di erent slots
De ning Classes
writer symbol The value is the identi er of the variable
to which the writer function will b e b ound The writer
function is a means to change the slot value The creation
defstruct de ning form
of the writer is analogous to that of the reader function
This option can b e sp eci ed more than once for a slot It
is an error to sp ecify the same reader writer or accessor
Syntax
name for two di erent slots
defstruct class name superclass slot description class
accessor symbol The value is the identi er of the vari
option
able to which the reader function will b e b ound In ad
dition the use of this slot option causes the creation of
Arguments
a writer function which is anonymous but asso ciated to
the reader via the setter mechanism This option can b e
class name A symb ol naming a binding to b e initiali sed sp eci ed more than once for a slot It is an error to sp ecify
with the new structure class the same reader writer or accessor name for two di erent
slots
superclass A symb ol naming a binding of a class to b e
used as the sup erclass of the new structure class The class options are interpreted as follows
Programming Language EuLisp version
Table defstruct syntax
class name identi er
superclass fan instance of structure class g
slot description slot name j slot name slot option
slot name identi er
slot option initarg identi er j
initform form j
reader reader name j
writer writer name j
accessor reader name
reader name identi er
writer name identi er
class option constructor constructor spec j
predicate predicate name
constructor spec constructor name init option
constructor name identi er
predicate name identi er
constructor constructor spec Creates containing the sup erclass If this list is empty the sup erclass
a constructor function for the new class The construc is object The third argument is a list of slot descriptio ns
tor sp eci cation gives the name to which the constructor the format of which is an extension of that for defstruct
function will b e b ound followed by a sequence of legal ini The remaining arguments are class options The syntax of
targs for the class The new function creates an instance defclass is given in Table All the slot options and class
of the class and lls in the slots according to the match options are exactly the same way as for defstruct
b etween the sp eci ed initargs and the given arguments to
the constructor function This option may b e sp eci ed any
numb er of times for a class Sp ecifying the constructor in
slot description class
this way is equivalent to writing a defconstructor form
for the class
The abstract class of all slot descriptions
predicate symbol Creates a predicate function for the
new class The predicate sp eci cation gives the name to
which the predicate function will b e b ound This option Creating Ob jects
may b e sp eci ed any numb er of times for a class Sp eci
fying the constructor in this way is equivalent to writing
make function
a defpredicate form for the class
Arguments
defclass de ning form
class The class of the ob ject to create
Syntax
key obj key obj Initializati on arguments
1 1 n n
defclass class name superclass slot description
class option
Result
An instance of class
Arguments
Remarks class name A symb ol naming a binding to b e initiali sed
with the new class
The general constructor make creates a new ob ject calling
allocate and initial izes it by calling initialize allocate
superclass A list of a single symb ol naming the bind
discriminates on the class while initialize discrimina tes
ing of the class to b e used as the sup erclass of the new
on the new ob ject
class Multiple sup erclasses can b e sp eci ed at level see
section B
telos condition condition
slot description A list of slot sp eci cations see b e
low comprising either a slot name or a list of a slot name
followed by some slot options
This is the general condition class for conditions arising from
op erations in the ob ject system
class option A sequence of keys and values see b elow
Remarks
This de ning form de nes a new class The resulting class
will b e b ound to class name The second argument is a list
Programming Language EuLisp version
Table defclass syntax level
class name identi er
superclass f class or the name of one of its subclassesg
slot description slot name j slot name slot option
slot name identi er
level slot option initarg identi er j
initform form j
reader reader name j
writer writer name j
accessor reader name j
level class option constructor constructor spec
predicate predicate name
Arguments Generic Functions and Metho ds
gf name One of a symb ol or a form denoting a setter
A generic function is a function whose application b ehaviour
function or a converter function
is determined by the classes of its arguments Each p otential
b ehavior is de ned by a metho d which sp eci es a signature
gen lambda list The parameter list of the generic func
of classes for which it is applicable A program s proto col
tion which may b e sp ecialised to restrict the domain of
is a set of generic functions and the relationships b etween
metho ds to b e attached to the generic function
them
init option Options as sp eci ed b elow
Generic functions replace the send construct found in many
ob ject oriented languages In contrast to sending a message
to a particular ob ject which it must know how to handle
Remarks
the metho d executed by a generic function is determined by
This de ning form de nes a new generic function The re all of its arguments Metho ds which sp ecialize on more than
one of their arguments are called multi methods
sulting generic function will b e b ound to gf name The
second argument is the formal parameter list An er
Generic functions are de ned using the defgeneric de ning
ror is signaled condition non congruent lambda lists
if any metho d de ned on this generic function do es not form which creates a named generic function in the top
lexical environment of the mo dule in which is app ears and
have a lamb da list congruent to that of the generic
function In addition an error is signaled condition generic lambda which creates an anonymous generic func
tion These forms are describ ed in detail later in this section
incompatible method signature if the metho d s sp ecial
ized lamb da list widens the domain of the generic function
A metho d describ es the applicatio n b ehaviour of a generic
In other words the lamb da lists of all metho ds must sp e
function for a particular sequence of classes called the cialize on sub classes of the classes in the lamb da list of the
metho d s domain Metho ds are not functions themselves
generic function This applies b oth to metho ds de ned at
but ob jects attached to a generic function containing closed the same time as the generic function and to any metho ds
expressions
added subsequently by defmethod or add method An init
option is a identi er followed by a corresp onding value The
Like slots metho ds are inherited from the sup erclass es of
syntax of defgeneric is given in Table
an ob ject That is if a metho d is applicabl e for a class
C it is also applicable for all of C s sub classes as well
The init option is
1 1
New metho ds may also b e de ned for these sub classes and
these metho ds are said to b e more speci c than the meth
method method spec This option is followed by a metho d
o ds de ned on the sup er classes However the more general
description A metho d description is a list comprising the
metho ds are accessible from the more sp eci c through the
sp ecialized lamb da list of the metho d which denotes the
call next method form Thus b ehavior can b e inherited
signature and a sequence of forms denoting the metho d
and extended in sub classes
b o dy The metho d b o dy is closed in the lexical envi
ronment in which the generic function de nition app ears
Metho ds can either b e de ned at the same time as the generic
This option may b e sp eci ed more than once
function or else de ned separately using the defmethod
macro which adds a new metho d to an existing generic func
Examples
tion This macro is describ ed in detail later in this section
In the following example of the use of defgeneric a generic
function named gf is de ned with three metho ds attached
to it The domain of gf is constrained to b e object
De ning Generic Functions and Metho ds
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
defgeneric de ning form
which is to say that class c class e and class g
must all b e sub class of class a
Syntax
defgeneric gf arg arg class a
defgeneric gf name gen lambda list level init option method m arg class b m arg class c
Programming Language EuLisp version
Table defgeneric syntax level
gf name identi er j setter identi er j converter identi er
gen lambda list spec lambda list
level init option method method description
method description spec lambda list form
spec lambda list spec variable variable
spec variable variable class j variable
class class name
method m arg class d m arg class e Remarks
method m arg class f m arg class g
Signalled by add method if the signature of the metho d
would widen the domain that is is less sp eci c than the
generic function
See also add method
non congruent lambda lists telos condition
defmethod macro
Init options
Syntax
generic function The generic function to b e extended
defmethod gf name spec lambda list form
or
method method The metho d to b e added
defmethod setter identi er spec lambda list form
or
defmethod converter identi er spec lambda list form
Remarks
Signalled by add method if the lamb da list of the metho d is
not congruent to that of the generic function
Remarks
This macro is used for de ning new metho ds on generic func
tions A new metho d ob ject is de ned with the sp eci ed
Sp ecializing Metho ds
b o dy and with the signature given by the sp ecialized lamb da
list This metho d is added to the generic function b ound to
The following op erators
gf name or convertor function asso ciated with class In the
call next method and next method p are used to sp e
former case if the sp ecialized l amb da li st is not congruent
cialize more general metho ds by calling them and p erhaps
with that of the generic function an error is signaled condi
p erforming some additional computations b efore and or af
tion non congruent lambda lists In addition an error
ter calling the next metho d It is an error to use either of
is signaled condition incompatible method signature if
these op erators outside a metho d b o dy Argument bindings
the metho d s sp ecialized lamb da list would widen the domain
inside metho ds are immutable Therefore an argument in
of the generic function
side a metho d retains its sp ecialize d class throughout the
pro cessing of the metho d
no applicable method telos condition
call next method special form
Init options
Syntax
generic function The generic function which was ap
call next method
plied
domain list The domain of the sought metho d
Result
The result of calling the next most sp eci c applicabl e
metho d
Remarks
Signalled by the discriminati ng function of a generic function
when there is no metho d which satis es the given signature
Remarks
The next most sp eci c applicable metho d is called with the
same arguments as the current metho d An error is signaled
incompatible method signature telos condition
condition no next method if there is no next most sp eci c
metho d
Init options
no next method telos condition
generic function The generic function to b e extended
Init options method method The metho d to b e added
Programming Language EuLisp version
method method The metho d which called Threads and Semaphores
call next method
The basic elements of parallel pro cessing in EULISP are pro
operand list list A list of the arguments to have b een
cesses and mutal exclusion which are provided by the classes
passed to the next metho d
thread and semaphore resp ectively
A thread is an abstract data typ e protecting some
Remarks
implementation de ned data A thread is allo cated and ini
Signalled by call next method if there is no next most sp e tialised like all other ob ject by using make This function
ci c metho d is called the initial function and is where execution starts
the rst time the thread is dispatched by the scheduler The
discussion identi es four states of a thread new running
ab orted and nished These are for conceptual purp oses only
next method p special form
and are not distinguish abl e in practice The transitions b e
tween these states are summarised in gure The initial
Syntax
state of a thread is new The union of the two nal states is
known as determined
next method p
A thread is made available for dispatch by starting it us
Result
ing the function thread start which changes its state to
running From running a thread b ecomes either nished or
If there is a next most sp eci c metho d next method p re
ab orted When a thread has nished the result of the initial
turns a non value otherwise it returns
function may b e accessed using thread value If a thread
is ab orted which can only o ccur as a result of a signal han
dled by the default handler then thread value will signal
the condition on the thread accessing the value Note that
thread value blo cks until the sp eci ed thread has b een de
termined
Access to shared resources or an undetermined thread while
a thread is running may cause it to b ecome blo cked Thus
a thread may b e blo cked on a semaphore input output or
thread value In each of these cases thread resechedule
is called to allow another thread to execute This function
may also b e called voluntarily A thread may b e unblo cked
by some other thread executing close semaphore on the
semaphore on which the rst thread is blo cked Thus the
call to thread reschedule returns
The actions of a thread can b e in uenced externally by
signal This function registers a condition to b e sig
nalled when the sp eci ed thread is rescheduled for execu
tion The condition must b e an instance of a sub class of
thread condition Conditions are delivered to the thread
in order of receipt A signal on a determined thread has no
e ect on either the signalled or signalli ng thread See also
section
A semaphore is an abstract data typ e protecting a binary
value call these values zero and one The op erations on a
sempahore are close semaphore and open semaphore The
open semaphore op erations sets the value to zero if it is one
or changes the state of the thread executing the op eration
to blocked if the value is zero and reschedules the thread
The close semaphore op eration sets the value to one and if
there are any threads blo cked on this semaphore one will b e
selected and unblo cked
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
a A pro cessor is free to use run to completion timeslic
ing and or concurrent execution
b A conforming program must assume the p ossibility of
concurrent execution of threads and will have the same
Programming Language EuLisp version
Figure State diagram for threads
change the data If it is not using a semaphore the fairness
guarantee ensures that in the same scenario the following
lo op will exit eventually
make
while data thread reschedule
V
NEW
Threads
thread start
V
The de ned name of this mo dule is thread This section
RUNNING
de nes the op erations on threads
default initial
signal function
thread class
handler returns
V V
ABORTED FINISHED
The class of all instances of thread
Init options
semantics in all cases see discussion of fairness which fol
lows
initfn initial function an instance of function which
will b e called when the resulting thread is started
c The default condition handler for a new thread when
invoked will change the state of the thread to aborted
size integer a p ositive integer sp ecifying in
save the signalled condition and reschedule the thread
implementation de n ed units the size of the thread to b e
allo cated
d An error is signaled condition wrong thread if a
continuation is called from a thread other than the one on
which it was created That is to say a continuation must
threadp function
only b e called from within its dynamic extent
e The lexical environment inner and top asso ciated
Arguments
with the initial function is shared by the thread as is the
top dynamic environment but each thread has a distinct
obj ob ject to examine
inner dynamic environment
Result
f The creation and starting of a thread represent
changes to the state of the pro cessor and as such are not
The supplied argument if it is an instance of thread other
a ected by the pro cessor s handling of errors signaled sub
wise
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
side the creation of the subsidiary thread has no default
thread reschedule function
e ect on the subsidiary thread
g The b ehaviour of i o on the same stream by multiple
This function takes no arguments
threads is unde ned
Result
The parallel semantics are preserved on a sequential run
to completion implementation by requiring communication
The result is
b etween threads to use only thread primitives and shared
data protected by semaphores b oth the thread primitives
Remarks
and semaphores will cause rescheduling so other threads can
b e assumed to have a chance of execution
This function is called for side e ect only and causes the
thread which executes it to b ecome blo cked If conditions are
There is no guarantee ab out which thread is selected next
p ending on the thread when thread reschedule continues
However a fairness guarantee is needed to provide the il
one is selected arbitrarily and signalled No further p ending
lusion that every other thread is running A strong guar
conditions will b e signalled until the handler pro cessing the
antee would ensure that every other thread gets scheduled
condition has exited Up on exit from the handler the thread
b efore a thread which reschedules itself is scheduled again
is rescheduled again
Such a scheme is usually called round robin This could
b e stronger than the guarantee provided by a parallel imple
See also thread value thread signal
mentation or the scheduler of the host op erating system
A weak but su cient guarantee is that if any thread resched
ules in nitely often then every other thread will b e scheduled
current thread function
in nitely often Hence if a thread is waiting for shared data
to b e changed by another thread and is using a semaphore
the other thread is guaranteed to have the opp ortunity to This function takes no arguments
Programming Language EuLisp version
Result
wait method
The thread on which current thread was executed
Sp ecialized Arguments
thread start function
thread thread The thread on which to wait
Arguments
timeout object The timeout p erio d
thread the thread to b e started which must b e in state
Result
new If not an error is signaled condition old thread
Returns thread if thread is determined
obj obj values to b e passed as the arguments to the
1 n
initial function of thread
See also wait
Result
thread condition condition
The thread which was was supplied as the rst argument
Init options
Remarks
current thread thread Thread which is signalling the
The state of thread is changed to running The values ob j
condition 1
to ob j will b e passed as arguments to the initial function of
n
thread
Remarks
This is the general condition class for all conditions arising
from thread op erations
thread value function
Arguments
wrong thread thread condition
thread the thread whose nished value is to b e accessed
Init options
continuation continuation A continuation
Result
The result of the initial function applied to the arguments
thread thread Thread on which continuation was cre
passed from thread start However if a condition is sig
ated
nalled on thread which is handled by the default handler
the condition will now b e signalled on the thread executing
Remarks
thread value
Signalled if the given continuation is called on a thread other
than the one on which it was created
Remarks
If thread is not determined the thread executing
old thread thread condition
thread value is blo cked until thread is determined
Init options
See also thread reschedule thread signal
thread thread A thread
Result
Remarks
The result is
Signalled by thread start if the given thread has b een
started already
Remarks
Registers the sp eci ed condition or by default an instance
generic prin method
of thread condition to b e signalled when thread is resched
uled for execution A thread signal on a determined thread
has no e ect on either the signalled or signalli ng thread
generic write method
Sp ecialized Arguments See also thread reschedule thread value
Programming Language EuLisp version
thread thread The thread to b e ouptut on stream
close semaphore function
stream stream The stream on which the represen
tation is to b e output
Arguments
semaphore the semaphore to b e closed
Result
The thread supplied as the rst argument
Result
The semaphore supplied as argument
Remarks
Outputs the external representation of thread on stream
Remarks
The external representation of thread is pro cessor de ned
Set the value of semaphore to one and if there are any threads
blo cked on this semaphore select one and unblo ck it This
op eration is atomic That thread may then attempt to op en
Semaphores
the semaphore again
The de ned name of this mo dule is semaphore
See also open semaphore
semaphore class
generic prin method
The class of all instances of semaphore This class has no
Arguments
init options The result of calling make on semaphore is a
new op en semaphore
semaphore the semaphore to b e ouptut on stream
stream the stream on which the representation is to b e
output
semaphorep function
Result
Arguments
The thread supplied as the rst argument
obj ob ject to examine
Remarks
Outputs the external representation of semaphore on stream
Result
The external representation of semaphore is pro cessor
The supplied argument if it is an instance of semaphore
de ned
otherwise
generic write method
open semaphore function
Arguments
Arguments
semaphore the semaphore to b e ouptut on stream
semaphore the semaphore to b e op ened
stream the stream on which the representation is to b e
output
Result
Result
The semaphore supplied as argument
The thread supplied as the rst argument
Remarks
Remarks
Set the value of semaphore to zero if it is one or blo ck the
Outputs the external representation of semaphore on stream
thread executing open semaphore if the value is to zero and
The external representation of semaphore is pro cessor
call thread reschedule This op eration is atomic On b e
de ned
ing unblo cked the call to open semaphore will continue by
attempting to op en the semaphore
See also close semaphore
Programming Language EuLisp version
Figure Level initial condition class hierarchy
Conditions
condition condition class
The de ned name of this mo dule is condition
execution condition condition
invalid operator condition
The condition system owes much to the Common Lisp er
bad apply argument condition
ror system Pitman and to the Standard ML excep
cannot update setter condition
tion mechanism It is a simpli cati on of the former and an
no setter condition
extension of the latter Following standard practice this
improper unquote splice condition
do cument has de ned the b ehaviour of functions in terms
environment condition condition
of their normal b ehaviour Where an exceptional b ehaviour
arithmetic condition condition
might arise this has b een de ned in terms of a condition
division by zero condition
However not all exceptional situations are errors Following
conversion condition condition
Pitman we use condition to b e a kind of o ccasion in a pro
no converter condition
gram when an exceptional situation has b een signaled An
stream condition condition
error is a kind of condition e rror and condition are also used
syntax error condition
as terms for the ob jects that describ e exceptional situations
thread condition condition
A condition can b e signaled continuably or non continuabl y
telos condition condition
no next method condition
These two classes are characterised as follows
non congruent lambda lists condition
incompatible method signature condition
a A condition might b e signaled when some limit has
no applicable method condition
b een transgressed and some corrective action is needed
b efore pro cessing can resume For example memory zone
exhaustion on attempting to heap allo cate an item can b e
corrected by calling the memory management scheme to
execution condition condition
recover dead space However if no space was recovered a
new kind of condition has arisen Another example arises
in the use of IEEE oating p oint arithmetic where a con
This is the general condition class for conditions arising from
dition might b e signaled to indicate divergence of an op
the execution of programs by the pro cessor
eration A continuable condition should b e signaled when
there is a strategy for recovery from the condition
environment condition condition
b Alternatively a condition might b e signaled when
some catastrophic situation is recognised such as the
This is the general condition class for conditions arising from
memory manager b eing unable to allo cate more memory
the environment of the pro cessor
or unable to recover su cent memory from that already
allo cated a non continuable condition should b e signaled
when there is no reasonable way to resume pro cessing
Condition Handling
A condition class is de ned with defcondition or defclass
Conditions are handled with a function called a hand ler
The de nition of a condition causes the creation of a new
Handlers are established dynamicall y and have dynamic
class of condition including a new condition class construc
scop e and extent Thus when a condition is signaled the
tor A condition is signaled using the function signal which
pro cessor will call the dynamically closest handler Note that
takes an instance of a condition and a resume continuation
it is the rst handler accepting to pro cess the condition that
or the empty list signifying a non continuabl e condition as
is used and not necessarily the most sp eci c Handlers are
arguments A condition can b e handled using the sp ecial
established by the sp ecial form with handler
form with handler which takes a function the handler
function and a sequence of forms to b e protected The
initial condition class hierarchy is shown in Figure
signal function
Called to indicate that sp eci ed condition has arisen during
the exection of a program
condition class
Arguments
Init options
condition The condition to b e signaled
message string A string continaing information which
should p ertain to the situation which caused the condition
function The function or continuation to b e called if
to b e signalled
the condition is handled and resumed that is to say the
condition is continuable
thread If this argument is not supplied the condition
is signalled on the thread which called signal otherwise
Remarks
thread indicates the thread on which condition is to b e
signalled
The class which is the sup erclass of all condition classes
Programming Language EuLisp version
Result Remarks
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
establishment of the new hand ler function
If the third argument is not supplied signal calls the dy
namically closest handler with condition the condition b e
c The sequence of protected forms is evaluated in order
ing signaled an d either continuation or If the second
and the value of the last one is returned as the result of
argument is a sub class of function that is the resume con
the with handler expression
tinuation to b e used in the case of a handler deciding to re
sume from a continuable condition If the second argument
d the hand ler function is disestablis hed and the previ
is it indicates that the condition was signaled as a non
ous handler is no longer shadowed
continuable condition i n this way the handler is informed
of the signaler s intention
The ab ove is the normal b ehaviour of with handler The
exceptional b ehaviour of with handler happ ens when there
If the third argument is supplied signal registers the
is a call to signal during the evaluation of protected form
sp eci ed condition to b e signalled when thread is resched
signal calls the dynamicall y closest hand ler function pass
uled for execution The condition must b e an instance of
ing on the two arguments given to signal The hand ler
thread condition otherwise an error is signalled condi
function is executed in the dynamic extent of the call to
tion wrong condition class on the thread calling signal
signal However any signals o ccurring during the exe
A signal on a determined thread has no e ect on either the
cution of hand ler function are dealt with by the dynami
signalled or signallin g thread
cally closest handler outside the extent of the form which
established hand ler function A hand ler function takes one
of three actions
See also thread reschedule thread value
with handler
a Return This causes the next closest enclosing
hand ler function to b e called passing on the condition
and the resume continuation This is termed declining
the condition The situation when there is no next closest
wrong condition class thread condition
enclosing handler is discussed later
b Call the resume continuation This action might b e
Init options
taken if the condition is recognised by the handler function
and might b e preceded by some corrective action This is
condition condition A condition
termed resuming the condition
Signalled by signal if the given condition is not an instance
c Not return and not call the resume continuation This
of thread condition
action might b e taken if the condition is recognised by the
handler function and might b e preceded by some corrective
action b efore some kind of transfer of control This is
termed accepting the condition
with handler special form
It is an error if the condition is declined and there is no next
closest enclosing handler In this circumstance the identi ed
Syntax
error is delivered to the con guration to b e dealt with in an
with handler handler function protected form
implementation de ned way
Examples
Arguments
An illustration of the use of all three cases is given in the
hand ler function A function or a generic function which
following unrealistic example
will b e called if a condition is signaled during the
synamic extent of protected forms A handler function
let cc accept
takes two arguments a condition and a resume func
with handler
generic lambda condition resume
tion continuati on The condition is the condition ob ject
method error xable return to cerror resume
that was passed to signal as its rst argument The re
c continuable condition
sume continuation is the continuation or that was
resume fix condition
given to signal as its second argument
method serious error exit from with hand ler accept
c condition
protected form The sequence of forms whose execution
accept
is protected by the hand ler function sp eci ed ab ove
otherwise by omission let another hand ler deal
with it decline
the protected expression
Result
something which might signal an error
The value of the last form in the sequence of protected forms
Programming Language EuLisp version
See also signal init option a sequence of options to b e passed to
initialize instance when making the instance of con
dition
Conditions
Result
conditionp function
The result of b oth of these functions is
Arguments
Remarks
obj ob ject to examine
The cerror and error functions signal continuable and non
continuable errors resp ectively Each calls signal with an
instance of a condition of condition class initiali zed from init
Result
option s the error message and a resume continuation In the
Returns obj if obj is a sub class of condition otherwise
case of cerror the resume continuation is the continuation
of the cerror expression In the case of error it is
signifying that the condition was not signaled continuably
condition message function
cerror and error can b e de ned in terms of more primitive
op erations
Arguments
cerror error message condition init arg
condition an instance of condition
let cc cerror fixed up
let c make condition init arg
signal c cerror fixed up
Result
return comes here
no hand ler c cerror fixed up
Returns the contents of the message slot of condition which
resume comes here
is a string
error error message condition init arg
initialize instance method
let c make condition init arg
signal c
return comes here
Arguments
no hand ler c
condition an instance of condition
The function no hand ler is that which changes the state of
the thread to aborted and saves the signaled condition for
init option a sequence of options
future reference This function is called after all handlers
have declined the condition That is no hand ler is only
called when none of the handlers can deal with the condition
Result
Note that b oth the condition and the resume continuation
A new initiali sed condition
are given to no hand ler as for any other handler function
so that for instance execution could b e resumed from the
debugger Also note that no hand ler is called in the envi
Remarks
ronment of the signal so that all the handlers in force at
the time of signaling are also in force during the call to no
First calls call next method to carry out initializ atio n sp ec
hand ler
i ed by sup erclasses then do es the condition sp eci c ini
tialization The following init option is recognised by this
metho d
defcondition de ning form
message The value must b e a string which should b e
used to convey information ab out the condition that has
arisen
Syntax
defcondition condition na me sup erclass init option
error function
Arguments
condition name A symb ol naming a binding to b e ini
cerror function
tialised with the new condition class
superclass A symb ol naming a binding of a class to b e
Arguments
used as the sup erclass of the new condition class
error message a string containing relevant information
init option A sequence of symb ols and expressions to
b e passed to al locate instance and initialize instance
condition class the class of condition to b e signalled
Programming Language EuLisp version
Remarks Expressions De nitions and Control
Forms
This de ning form de nes a new condition class The rst
argument is the name to which the new condition class will
This section gives the informal syntax of well formed expres
b e b ound The second is the sup erclass of the new condition
sions and describ es the semantics of the sp ecial forms func
and an init option is a identi er followed by its default
tions and macros of the level language In the case of level
initial value If superclass is the sup erclass is taken to b e
macros the description is augmented with an expansion
condition Otherwise superclass must b e condition or one
which has the required semantics However these descrip
of its sub classes
tions are not prescriptive of any pro cessor and a conforming
program cannot rely on adherence to these expansions
Atomic Expressions
constant syntax
There are two kinds of constant literal constants and de ned
constants The latter are considered under symbols A literal
constant is a numb 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 The external representation
of the empty list is The empty list is the only instance
of the class null For historical reasons the symb ol nil is
de ned to b e immutably b ound to the empty list
Examples
the empty list
a single precision integer
a a character
abc a string
defconstant de ning form
Syntax
defconstant identi er form
Arguments
identi er A symb ol naming an immutable top lexical
binding containing the value of form
form The form whose value will b e stored in the binding
of identi er
Remarks
The value of form is stored as the mo dule value of name It
is an error to set the value of a de ned constant to a di erent
value
symbol syntax
The current lexical binding of symbol is returned A symb ol
can also name a de ned constant that is an immutable
top lexical binding The de ned constant t has the value t
The de ned constant nil has the value which represents
the abstract b o olean value false The abstract b o olean value
true can represented by any value other than false that is
other than
Programming Language EuLisp version
Result
deflocal de ning form
A function with the sp eci ed lambda list and body
Syntax
Remarks
deflocal identi er form
The function construction op erator is lambda Access to the
lexical environment of de nition is guaranteed which may
cause the creation of a closure The syntax of lambda list is
Arguments
de ned by the following grammar
identi er A symb ol naming a binding containing the
lambda list identi er j simple list j rest list
value of form
simple list identi er
+
rest list identi er identi er
form The form whose value will b e stored in the binding
of identi er
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
Remarks
the arguments are b ound to the corresp onding identi ers
The value of form is stored as the mo dule binding value of
Otherwise lambda list must b e a rest list In this case each
name The binding created by a deflocal form is mutable
identi er preceding the dot is b ound to the corresp onding
argument and the identi er succeeding the dot is b ound to
a newly allo cated list whose elements are the remaining ar
Literal Expressions
guments These bindings have lexical scop e and extent It
is an error if the same identi er app ears more than once in
a lambda list quote special form
Syntax
function call special form
quote datum
Syntax
Arguments
operator operand
datum the datum to b e quoted
Arguments
Result
operator This may b e a symb ol b eing either the name
The result is datum
of a sp ecial form or a lexical variable or a function call
which must result in an instance of function An error is
signaled condition invalid operator if the op erator is
Remarks
neither the name of a sp ecial form nor a function
The result of pro cessing the expression quote datum is da
tum The ob ject datum can b e any external representation of
operand Each operand must b e either an atomic expres
a EULISP ob ject The sp ecial form quote can b e abbreviated
sion a literal expression or a function call
using apostrophe graphic representation in the standard
tokenisation scheme so that quote a can b e written a
Result
These two notations are used to incorp orate literal constants
in programs It is an error to mo dify the contents of a literal
The result is the result of the application of operator to the
expression Within a single mo dule multiple references to
evaluation of operand
the same eq literal pro duce the same literal
Remarks
Functions Application De nition
The operand expressions are evaluated in order from left to
right The operator expression may b e evaluated at any time
lambda special form
b efore during or after the evaluation of the op erands
Syntax
See also constant symbol quote
lambda lambda list body
invalid operator execution condition
Arguments
lambda list The parameter list of the function conform
Init options
ing to the syntax sp eci ed b elow
invalid operator object The ob ject which was b eing
body A sequence of forms
used as an op erator
Programming Language EuLisp version
operand list list The op erands prepared for the op er
ator
apply function
Remarks
Syntax
Signalled by function call if the op erator is not an instance
apply function obj obj
1 n
of function
Arguments
defmacro de ning form
function An expression which must evaluate to an in
stance of function
Syntax
defmacro macro name lambda list body
obj obj A sequence of expressions which wil b e
1 n 1
evaluated according to the rules given in function call
Arguments
obj An expression which must evaluate to a prop er list
n
An error is signaled condition bad apply argument if
macro name A symb ol naming a binding containing the
obj is not a prop er list
n
function with the sp eci ed lambda list and body
lambda list The parameter list of the function conform
Result
ing to the syntax sp eci ed under lambda
The result is the result of calling function with the actual
parameter list created by app ending obj to a list of the
n
body A sequence of forms
arguments obj through obj An error is signalled con
1 n 1
dition invalid operator if the rst argument is not an
instance of function
Remarks
The defmacro form de nes a function named by macro name
and stores the de nition as the mo dule binding value of
See also function call
macro name In addition the function macro name is ex
p orted with the syntax attribute set The interpretation of
the lambda list is as de ned for lambda see section
bad apply argument execution condition
The binding created by defmacro is immutable
Init options
See also lambda
arglist list A list of the ob jects passed to apply
defun de ning form
Remarks
Signalled by apply if its rst argument is not an instance of
Syntax
function
defun function name lamb da list b o dy
or
defun setter function name lamb da list b o dy
Assignments
An assignment op eration mo di es the contents of a binding
Arguments
named by a identi er that is a variable
The rst argument can take two forms
setq special form
function name A symb ol naming a binding contain
ing the function with the sp eci ed lambda list and body
Syntax
setter function name An expression denoting
the setter function to corresp ond to function name
setq identi er expression
lambda list The parameter list of the function conform
Arguments
ing to the syntax sp eci ed under lambda
identi er The identi er whose lexical binding is to b e
body A sequence of forms
up dated
Remarks
form An expression whose value is to b e stored in the
The defun form de nes a function named by function name
binding of identi er
and stores the de nition as the mo dule value of function
name The interpretation of the lambda list is as de ned for
Result
lambda see section The binding created by defun is
The result is the value of form immutable
Programming Language EuLisp version
Remarks Conditional Expressions
The form is evaluated and the result is stored in either the
closest lexical binding named by identi er It is an error to
if special form
mo dify an immutable binding
Syntax
setter function
if expression expression expression
Arguments
Arguments
access function An expression which must evaluate to antecedent An expression which may evaluate to any ob
an instance of function ject
consequence An expression which may evaluate to any
Result
ob ject
The update function corresp onding to access function
alternative An expression which may evaluate to any ob
ject
Remarks
A generalized place up date facility is provided by setter
Result
Given access function setter returns the corresp onding up
Either the value of consequence or alternative dep ending on
date function If no such function is known to setter an er
the value of antecedent
ror is signaled condition no setter Thus setter car
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
Remarks
tion which is accessed by the expression setter setter
The antecedent is evaluated If the result is true the conse
Thus setter setter an accessor an updator installs
quence is evaluated otherwise the alternative is evaluated
the function which is the value of an updator as the up dator
Both consequence and alternative must b e sp eci ed The
of the accessor function which is the value of an accessor
result of if is the result of the evaluation of whichever of
De ned up dator functions in this rep ort have the same im
consequence or alternative is chosen consequence is a single
mutable status as other standard functions such that at
form but alternative is a sequence of forms Each form in al
tempting to rede ne such a function for example setter
ternative is evaluated in order and the result of the last form
setter car a new value signals an error condition
is the result of the if expression Additional conditional
cannot update setter
forms when unless are given in section B
See also defun defmethod
cond macro
no setter execution condition
Syntax
cond antecedent form
Init options
object object The ob ject given to setter
Remarks
The cond macro provides a convenient syntax for collections
of if then elif else expressions The rewrite rules for cond
Remarks
are
Signalled by setter if there is no up dator for the given func
tion
cond
cond antecedent or antecedent
cond t form progn form
cannot update setter execution condition
or antecedent cond
1
cond antecedent
1
antecedent form antecedent form
2 2
Init options
if antecedent cond
1
progn form antecedent form
accessor object The given accessor ob ject
1
1
cond antecedent form
2
antecedent form
2
updator object The given up dator ob ject
2
Remarks
and macro
Signalled by setter setter if the up dator of the given
accessor is immutable
Syntax
and form See also setter
Programming Language EuLisp version
Remarks See also block return from
The expansion of an and form leads to the evaluation of the
sequence of forms from left to right The the rst form in
the sequence that evaluates to stops evaluation and none labels special form
of the forms to its right will b e evaluated The result of and
is If none of the forms evaluate to the value of the
Syntax
last form is returned The rewrite rules for and are
labels function name lambda list body labels body
and t
Remarks
and form form
and form form if form and form
The labels op erator provides for lo cal mutually recursive
1 2 1 2
function creation Each function name is b ound to a new
lo cation holding an unsp eci ed value making a new envi
ronment extended by those bindings Then for each set of
or macro
formal parameters and body a function is constructed using
lambda and the binding of the corresp onding function name
Syntax
is up dated to have the value of the lamb da expression The
scop e of the function names is the entire labels form The
or form
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 ab ove extended environment The result of evaluating
Remarks
the last form is returned as the result of the labels form
The expansion of an or form leads to the evaluation of the
sequence of forms from left to right The value of the rst
form that evaluates to true is the result of the or form and
let macro
none of the forms to its right will b e evaluated If none of the
forms evaluate to true the value of the last form is returned
The rewrite rules for or are
Syntax
let identi er binding body
or
or form form
or form form let x form
1 2 1
Remarks
if x x or form
2
The optional identi er denotes that the let form can b e called
from within its body This is an abbreviation for labels com
where x do es not o ccur free in any of form form
2 n
bined with let A binding is sp eci ed by either an identi er
or a two element list of an identi er and an initiali zin g form
All the initiali zi ng forms are evaluated in order from left to
Variable Binding and Sequences
right in the current environment and the variables named
by the identi ers in the bindings are b ound to new lo cations
let cc special form
holding the results Each form in body is evaluated in order
in the environment extended by the ab ove bindings The
result of evaluating the last form in body is returned as the
Syntax
result of the let form The rewrite rule for let is
let cc identi er body
let form progn form
let id form lambda id id id
1 1 1 2 3
Arguments
id form form
2 2
id form form
3 1 2
identi er To b e b ound to the continuation of the let cc
form
form
body A sequence of forms
let macro
Result
Syntax
The result of evaluating the last form in body
let identi er binding body
Remarks
Remarks
The identi er is b ound to a new lo cation which is initial
The optional identi er denotes that the let form can b e called ized with the continuation of the let cc form This binding
from within its body This is an abbreviation for labels com is immutable and has lexical scop e and inde nite extent
bined with let A binding is sp eci ed by a two element list Each form in body is evaluated in order in the environment
of a variable and an initiali zi ng form The rst initializ in g extended by the ab ove binding It is an error to call the con
form is evaluated in the current environment and the corre tinuation outside the dynamic extent of the let cc form that
sp onding variable is b ound to a new lo cation containing that created it The continuation is a function of one argument
Programming Language EuLisp version
result Subsequent bindings are pro cessed in turn evaluat o ccur during the pro cessing of the after forms the after
ing the initiali zin g form in the environment extended by the forms b eing pro cessed are not reentered Instead control is
previous binding Each form in body is evaluated in order in transferred to wherever sp eci ed by the new non lo cal exit
the environment extended by the ab ove bindings The result but the after forms of any intervening unwind protects b e
of evaluating the last form is returned as the result of the tween the dynamic extent of the target of control transfer
let form The rewrite rules for let are and the current unwind protect are evaluated in increasing
order of dynamic extent
let form progn form
let var form let var form
1 1 1 1
var form let var form Waiting on Events
2 2 2 2
var var
3 3
wait generic function
form form
Arguments
progn special form
obj An ob ject
timeout One of t or an instance of integer
Syntax
progn form
Result
Returns if timeout was reached otherwise a non value
Arguments
form A sequence of forms and in certain circumstances
Remarks
de ning forms
wait provides a generic interface to blo cking op erations Ex
ecution of the current thread will continue b eyond the wait
form only when one of the following happ ened
Result
The sequence of forms is evaluated in order returning the
a A predicate asso ciated with obj returns true
value of the last one as the result of the progn form
b After timeout time units
Remarks
c A signal is received
If the progn form o ccurs enclosed only by progn forms and
a defmodule form then the forms within the progn can b e
wait returns if timeout o ccurs else it returns a non nil
de ning forms It is a static error if this rule is violated
value
A timeout argument of or zero denotes a p olling op era
tion A timeout argument of t denotes inde nite blo cking
unwind protect special form
A timeout argument of a non negative integer denotes the
minimum numb er of time units b efore timeout The numb er
of time units in a second is given by the implementation
Syntax
de ned constant ticks per second
unwind protect protected form after form
Examples
Arguments
This co de fragment copies characters from stream s to the
current output stream until no data is received on the stream
protected form A form
for a p erio d of at least second
after form A sequence of forms
labels
loop
when wait s cuckoo heartbeat
Result
print read char s
The value of protected form
loop
loop
Remarks
See also threads streams
The normal action of unwind protect is to pro cess protected
form and then each of after forms in order returning the
value of protected form as the result of unwind protect A
non lo cal exit from the dynamic extent of protected form
ticks per second double oat
which can b e caused by pro cessing a non lo cal exit form
will cause each of after forms to b e pro cessed b efore con
The numb er of time units in a second expressed as a trol go es to the continuation sp eci ed in the non lo cal exit
double precision oating p oint numb er This value is form The after forms are not protected in any way by the
implementation de ned current unwind protect Should any kind of non lo cal exit
Programming Language EuLisp version
Table Quasiquote Syntax
anti quotation
unquotation
unquote splice
quasiquotation quasiquotation
1
template expression
0
quasiquotation template j quasiquote template
i i i
template oneofsimple datum list template vector template unquotation
i i i i
+
list template template or splice j template or splice template j
i i
i
i
template j quasiquotation
i i+1
vector template template or splice
i
i
unquotation template j unquote template
i i 1 i 1
template or splice template j splicing unquotation
i i i
splicing unquotation template j unquote splicing template
i i 1 i 1
Quasiquotation Expressions attempting to unquote splice an improp er list The in
sertion of the result of an unquote spli ce expression is as if
the op ening and closing parentheses of the list are removed
and all the elements of the list are app ended in place of the
quasiquote macro
unquote splice expression
The syntax forms unquote and unquote splicing can b e
Syntax
abbreviated resp ectively by using the glyph called comma
quasiquote skeleton or skeleton
preceding an expression and by using the diphthong
comma followed by the glyph called commercial at pre
ceding a form Thus unquote a may b e written a and
Remarks
unquote splicing a can b e written a
Quasiquotation is also known as backquoting A
quasiquoted expression is a convenient way of buildin g a
structure The skeleton describ es the shap e and generally
improper unquote splice execution condition
many of the entries in the structure but some holes remain
to b e lled The quasiquote macro might b e abbreviated by
using the glyph called grave accent so that quasiquote
Init options
expression can b e written expression A complete de
nition of the syntax of quasiquote expressions is given in
skeleton skeleton The skeleton that unquote is pro cess
Table
ing
splice list list The improp er list which has lead to
unquote syntax
the error
Syntax
Remarks
Signalled by quasiquote unquote form or form
if the result of an unquote splicing form is not a prop er
list
Remarks
See unquote splicing
Summary of Level Expressions and Def
initions
unquote splicing syntax
The syntax of all level expressions and de nitions is given
in Table Any pro ductions unde ned here app ear else
where in the de nition sp eci cally the syntax of certain
Syntax
classes of data are de ned in their own sections
unquote splicing form or form
Remarks
The holes in a quasiquoted expression are identi ed by un
quote expressions of which there are two kinds forms whose
value is to b e inserted at that lo cation in the structure and
forms whose value is to b e spliced into the structure at that
lo cation The former is indicated by an unquote expres
sion and the latter by an unquote splicing expression In
unquote splice the form must result in a prop er list An
error is signaled condition improper unquote splice on
Programming Language EuLisp version
Table Expressions and De nitions level
level de nition defconstant j defcondition j de ocal j defmacro j defmodule j defstruct j defun
defcondition defcondition condition name superclass init option
defconstant defconstant identi er form
de ocal deflocal identi er form
defmacro defmacro macro name lambda list body
defmodule defmodule module name import spec syntax spec module expression
import spec module directive
syntax spec j syntax import spec defmacro
export spec export j export syntax j expose
export export name
export syntax export syntax name
expose expose module directive
module directive module name j module lter
module lter except j only j rename
+
except except name module directive
+
only only name module directive
+
rename rename old name new name module directive
module expression export spec j level expression j de nition j progn expression
de nition level de nition
fdefmoduleg
defgeneric defgeneric gf name gen lambda list level init option
gf name identi er j setter identi er j converter identi er
gen lambda list spec lambda list
level init option method method description
method description spec lambda list form
spec lambda list spec variable variable
spec variable variable class j variable
class class name
defstruct defstruct class name superclass slot description class option
defun defun function name lambda list body j
defun setter function name lambda list body
level expression lex ref j literal j procedure cal l j macro cal l j level special j quasiquotation
level special conditional j lambda j let cc j progn j lex assign j unwind protect j
with hand ler
lex ref identi er
literal quotation j self evaluating
quotation quote datum
lex assign setq identi er expression
conditional if expression expression expression
lambda lambda lambda list body
lambda list identi er j simple list j rest list
simple list identi er
+
rest list identi er identi er
let cc let cc identi er body
progn progn form
with hand ler with handler hand ler function protected form
unwind protect unwind protect protected form after form
self evaluating character j number j string j vector
procedure cal l procedure operator operand
macro cal l macro operator operand
procedure operator expression
operand expression
macro operator symbol
variable identi er
body expression
Programming Language EuLisp version
Annex A
normative
Level Mo dule Library
A Characters A Result
Returns obj if obj is an instance of a sub class character
The de ned name of this mo dule is character
otherwise
A character syntax
A converter integer method
Character literals are denoted by the extension glyph called
A Arguments
hash followed by the character extension glyph called
reverse solidus followed by the name of the character
character A character
For most characters their name is the same as the glyph as
so ciated with the character for example the character a
has the name a and has the external representation a
A Result
Certain characters in the group named special see Table
Returns an instance of single precision integer which
and also Table A have symb olic names for example the
corresp onds to the p osition of the instance of character in
newline character has the name new line and has the exter
the default character set
nal representation newline These sp ecial cases are the
characters named in Table A
Table A Sp ecial Character Syntax
A equal method
Name Syntax
alert alert
A Arguments
backspace backspace
delete delete
character an instance of character
1
formfeed formfeed
linefeed linefeed
character an instance of character
2
new line newline
return return
tab tab
A Result
space space
Each instance of character is converted to a integer and the
vertical tab vertical tab
two values are compared using The result of equal is the
rst argument if the result of is non If not the result
Any character which do es not have a name and thereby
is
an external representation dealt with by the ab ove cases is
represented by x followed by up to four hexadecimal dig
its The value of the hexadecimal numb er represents the
A copy method
p osition of the character in the current character set Exam
ples of such character literals are x and xabcd which
denote resp ectively the characters at p osition and at p o
A Arguments
sition in the character set current at the time of read
ing or writing The syntax for the external representation of
character A character
characters is de ned in Table A
NOTE At present this do cument refers to the current char
A Result
acter set but de nes no means of selecting alternative character
Constructs and returns an instance of character whose
sets This is to allow for future extensions and implementation
value is the same under equal as the source
de ned extensions which supp ort more than one character set
A character class
A generic prin method
The class of all instances of character
A generic write method
A characterp function
A Arguments
character Character to b e ouptut on stream
A Arguments
stream Stream on which character is to b e ouptut
obj Ob ject to examine
Programming Language EuLisp version
Table A Character Syntax
character extension character extension character name
character name literal name j special name j control name j numeric
literal name alphanumeric j non alpha
control name control extension literal name
special name alert j backspace j delete j formfeed j linefeed j newline j
return j tab j space j vertical tab
character extension
control extension
numeric string hex digit digit digit digit
A Result A Collections
The character character
The de ned name of this mo dule is collection A col lection
is de ned as an instance of one of string list vector
table or any user de ned class for which a metho d is added
A Remarks
to any of the collection manipulation functions Collection
Output the interpretation of character on stream
do es not name a class and do es not form a part of the class
hierarchy
A generic write method
A empty p generic function
A Arguments
A size generic function
character Character to b e ouptut on stream
stream Stream on which character is to b e ouptut
A member generic function
A Result
The character character
A do generic function
A Remarks
A map generic function
Output external representation of character on stream in the
format name as describ ed at the b eginning of this section
A reduce generic function
A reduce generic function
A fill generic function
A catenate generic function
A filter generic function
Programming Language EuLisp version
A Comparing Ob jects
A eql function
The de ned name of this mo dule is compare Four functions
for comparing ob jects are de ned in EULISP of which is
A Arguments
sp eci cally for comparing numeric values and eq eql and
equal are for all ob jects The latter three are related in the
following way obj
1
eq a b eql a b equal a b
obj
2
eq a b eql a b equal a b
A Result
If the class of obj and of obj is the same and is a sub class
1 2
A eq function
of number the result is that of comparing them under If
the class of obj and of obj is the same and is a sub class
1 2
of character the result is that of comparing them under
A Arguments
equal Otherwise the result is that of comparing them under
eq
obj an ob ject
1
obj an ob ject
2
A equal generic function
A Result
A Arguments
Compares obj and obj and returns t if they are the same
1 2
ob ject otherwise
obj
1
A Remarks
obj
2
In the case of numb ers and characters the b ehaviour of eq
might di er b etween pro cessors b ecause of implementation
A Result
choices ab out internal representations Therefore eq might
The result is determined by whichever of the metho ds de ned
return t or for numb ers which are and similarly for char
here is applicable It is implementation de ned whether or
acters which are equal dep ending on the implementation
not equal will terminate on self referential structures
A generic function
A See also Class sp eci c sections which de ne meth
o ds on copy
A Arguments
A equal method
number an instance of number
1
number an instance of number
2
A Arguments
A Result
object an ob ject
1
One of the arguments or
object an ob ject
2
A Remarks
A Result
De ned over all numb er typ es If b oth numb ers are of the
If the class of each instance of object is the same then the
same class they are compared according to the compari
result is the conjunction of the pairwise application of equal
son function for numb ers of that class If the two instances
to the contents of the slots of the arguments If not the result
are numerically equal the result is the rst argument a
is
non value If not the result is Metho ds are de
ned for the following classes single precision integer
variable precision integer ratio float and complex
In the case of complex the result is determined by the con
junction of the pairwise applicatio n of to the real parts and
the imaginary parts
If the numb ers are not of the same class then one of the num
b ers is converted to the class of the other numb er according
to the proto col given in section A
A See also Class sp eci c sections which de ne meth
o ds on copy single precision integer and double oat
Programming Language EuLisp version
A Conversion source object The ob ject to b e converted
class class The class with which no converter function
The de ned name of this mo dule is convert
is asso ciated
It may seem that the natural way to de ne convert obj
target class is as a generic function sp ecializi ng on b oth pa
A Remarks
rameters However b ecause we want the b ehaviour to de
p end on the target class and not on the class of target class
Signalled by convert if there is no converter function for the
we would have to use class prototyp es as in up to version
given target class
or eql metho ds in order to make it work Neither is
desirable Some classes that might b e targets for conversion
for instance pair number cannot easily have prototyp es
A converter function
b ecause they cannot have direct instances eql metho ds if
they are desirable at all are to o great a complication for
level This suggests that it may have b een a mistake to
A Arguments
think in terms of multi metho ds Fortunately if we forget
them and consider classical metho ds a fairly reasonable so
target class The class whose set of conversion metho ds
lution app ears
is required
Advantages are that it is ob ject oriented in a natural way
A Result
there is no need for class prototyp es or eql metho ds and it
is asymmetric in the right direction the converter of a class
The accessor returns the converter function for the class
converts to rather than from instance of the class
target class The converter is a generic function with meth
o ds sp ecialized on the class of the ob ject to b e converted
Disadvantages are that metho ds are not inherited from more
Note that all converters de ned here whose target class is
general target classes althou gh this could b e argued the
string pro duce a string containing a representation of the
other way round to o
source ob ject as if it had output by write
Conversion b etween classes is provided by the function
convert which accesses a set of converter functions using
A setter converter setter
the target class the second argument to convert as a key
The resulting converter function is a generic function which
discriminates on the class of the ob ject which is to b e con
A Arguments
verted
target class The class whose converter function is to b e
replaced
A convert function
generic function The new converter function
A Arguments
A Result
obj An instance of some class to b e converted to an in
The new converter function The setter function replaces
stance of class
the converter function for the class target class by generic
function The new converter function must b e an instance
class The class to which obj is to b e converted
of generic function
A Result
A See also Converter metho ds from one class to an
Returns an instance of class which is equivalent in some class
other are de ned in the section p ertaining to the source
sp eci c sense to obj which may b e an instance of any typ e
class
Calls the converter function asso ciated with the class 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 obj
to an instance of class
A conversion condition condition
This is the general condition class for all conditions arising
from conversion op erations
A no converter conversion condition
A Init options
Programming Language EuLisp version
Table A Metho ds for double precision oats
A Copying Ob jects
binary plus
The de ned name of this mo dule is copy
binary difference
negate
binary times
A copy generic function
binary divide
binary lt
abs
A Arguments
zerop
signum
obj An ob ject to b e copied
positivep
negativep
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
A Double Precision Floats
exact b ehaviour for each class of obj is de ned by the most
applicable metho d for obj
A double float syntax
A See also Class sp eci c sections which de ne meth
A oating p oint numb er has six forms of external repre
o ds on copy
sentation dep ending on whether either or b oth the whole
and the fractional part are sp eci ed and on whether an ex
p onent is sp eci ed In addition a p ositive oating p oint
A copy method
numb er is optionally preceded by a plus sign and a neg
ative oating p oint numb er is preceded by a minus sign
For example simple oat simple oat
A Arguments
simple oat and with exp onents D
D D
object An ob ject the default metho d
The syntax for the external representation of double preci
A Result sion oating p oint literals is de ned in Table A The rep
resentation used by write and prin is that based on simple
Constructs and returns an instance of the same class as the
oat without an exp onent namely sign simple oat
source whose slot values are the same as those of the source
Finer control over the format of the output of oating p oint
under eql so that the resulting ob ject is the same under
numb ers is provided by some of the formatting sp eci cations
equal as the source
of format see section A
The de ned name of this mo dule is double Arithmetic op
erations for double float are de ned by metho ds to b e at
tached to the generic functions listed in Table A
A double float class
The class of all instances of double precision oat
A double float p function
A Arguments
obj Ob ject to examine
A Result
If obj is an instance of float the result is obj otherwise
The function float returns obj if obj is a sub class of float
and the double float p returns obj if it is an instance of
double float Otherwise b oth return
Programming Language EuLisp version
Table A Floating Point Syntax
oat sign u oat
sign f j g
u oat simple oat exponent
simple oat simple oat j simple oat j simple oat
simple oat udecimal oat separator
simple oat oat separator udecimal
simple oat udecimal oat separator udecimal
oat separator
exponent dexpt mark sign udecimal
dexpt mark fd j Dg
+
udecimal digit
digit f j j g
A Result
A most positive double float double oat
Given one argument returns the greatest integer value whose
magnitude is less than or equal to x Given two arguments
with an integer value as the second to sp ecify precision re
A Remarks
turns a oating p oint numb er which is the result of zeroing
The value of most positive double float is that p ositive
out the low n pr ecision digits where n is the numb er of
double precision oating p oint numb er closest in value to
digits of precision provided by the representation It is an
but not equal to p ositive in nity that the pro cessor pro
error if pr ecision is greater than n
vides
A truncate method
A least positive double float double oat
A Remarks
A Remarks
Implements truncate for double float
The value of least positive double float is that p ositive
double precision oating p oint numb er closest in value to
but not equal to zero that the pro cessor provides This
value is the same as the result of succ
A round generic function
A least negative double float double oat
A Arguments
oat An instance of float
A Remarks
The value of least negative double float is that negative
precision A single precision integer
double precision oating p oint numb er closest in value to
but not equal to zero that the pro cessor provides Even if
the pro cessor provide negative zero this value must not b e
A Result
negative zero This value is the same as the result of pred
Given one argument returns the integer whose value is clos
est to x except in the case when x is exactly half way b e
tween two integers when it is rounded to the one that is
A most negative double float double oat
even Given two arguments with an integer value as the
second to sp ecify precision returns a oating p oint numb er
which is the result of zeroing out the low n pr ecision
A Remarks
digits where n is the numb er of digits of precision provided
The value of most negative double float is that negative
by the representation The numb er of digits of precision and
double precision oating p oint numb er closest in value to
the radix of the precision are implementation d e ned val
but not equal to negative in nity that the pro cessor pro
ues If the resulting value is exactly half way b etween two
vides
pr ecision digit oating p oint numb ers the result is the one
with the even least signi cant digit It is an error if pr ecision
is greater than n
A truncate generic function
A Arguments
A round method
oat An instance of float
A Remarks
precision A single precision integer
Implements round for double float
Programming Language EuLisp version
A Result
A floor generic function
Returns an instance of single precision integer whose
value is closest to that of the oating p oint source
This is the same function as round without sp ecifying
A Arguments
the second argument An error is signaled condition
integer conversion overflow if the oating p oint num
oat An instance of float
b er cannot b e represented as a single precision integer
A integer conversion overflow
A Result
conversion condition
Computes the greatest integer value which is less than or
equal to oat
A Init options
source double The double oat to b e converted
A floor method
A Remarks
A Remarks
Signalled by the double metho d of converter spint if
Implements floor for double float
the magnitude of the double oat is greater than can b e
reprented by a single precision integer
A ceiling generic function
A copy method
A Arguments
A Arguments
oat An instance of float
double oat A double precision oat
A Result
A Result
Constructs and returns an instance of double float whose
Computes the least integer value that is greater than or equal
value is the same under as the source
to oat
A generic prin method
A ceiling method
A generic write method
A Remarks
Implements ceiling for double float
A Arguments
x The double oat to b e output on stream
A converter string method
stream The stream on which the representation is to b e
output
A Arguments
A Result
double oat A double precision oat
The double oat supplied as the rst argument
A Result
A Remarks
Constructs and returns a string the characters of which cor
Output the external representation of x on stream as de
resp ond to the external representation of the instance of
scrib ed in the intro duction to this section namely sign
double float
simple oat Finer control over the format of the output of
oating p oint numb ers is provided by some of the formatting
sp eci cations of format see section A
A converter single precision integer method
A Arguments
double oat A double precision oat
Programming Language EuLisp version
A Elementary Functions
A atan generic function
The de ned name of this mo dule is elementary functions
The contents of this mo dule are de ned as if all the num
A Arguments
b er classes of EULISP exist including complex Dep end
ing on the level of conformance of a given implementation
only the metho ds for the numb er classes de ned at the level
z A numb er
of the pro cessor need b e supplied to provide a compliant
elementary functions library mo dule
A Result
atan returns the arc tangent of its argument The unit of the
argument is radians Metho ds are de ned for the appropriate
A pi double oat
sub classes of integer and float and for ratio and complex
The metho ds for integer and ratio co erce their argument
to float and then compute the result The metho d for float
A Remarks
pro duces a float result the metho d for complex pro duces a
The value of pi is the ratio the circumference of a circle to its
complex result
diameter stored to double precision oating p oint accuracy
A atan generic function
A sin generic function
A Arguments
A cos generic function
x x Two numb ers
1 2
A tan generic function
A Result
atan returns the arc tangent of the quantity x x treating
1 2
A Arguments
the case x correctly Metho ds are de ned for integer
2
integer float float and ratio ratio If the argu
z A numb er
ments are not of the same sub class of number but in the
set given ab ove the lower one is co erced to the class of the
higher according to the proto col for the level b eing used see
gure A The metho ds for integer and ratio co erce their
A Result
arguments to float and then compute the result A float
sin returns the sine of its argument cos the cosine and tan
result is returned
the tangent The unit of the argument is radians Metho ds
are de ned for the appropriate sub classes of integer and
The range of the real part of the values returned by atan
float and for ratio and complex The metho ds for integer
and atan is pi pi
and ratio co erce their argument to float and then compute
the result The metho ds for float pro duce a float result
the metho ds for complex pro duce a complex result
A exp generic function
A Arguments
A acos generic function
z A numb er
A asin generic function
A Result
A Arguments
exp returns e raised to the p ower of x where e is the base
of the natural logarithms Metho ds are de ned for the ap
z A numb er
propriate sub classes of integer and float and for ratio
and complex The metho ds for integer and ratio co erce
their argument to float and then compute the result The
metho d for float pro duces a float result the metho d for
A Result
complex pro duces a complex result
acos returns the principal arc cosine and asin the princi
pal arc sine of its argument The unit of the result is radi
ans Metho ds are de ned for the appropriate sub classes of
A log generic function
integer and float and for ratio and complex The meth
o ds for integer and ratio co erce their argument to float
and then compute the result The metho ds for float pro
duce a float result when z otherwise a complex
A log generic function
result The metho ds for complex pro duce a complex result
Programming Language EuLisp version
A Result
A log generic function
expt returns the principal value that results from raising z
1
to the p ower z The complexity in the de nition of expt
2
stems from the di erent combinations of argument classes
A Arguments
and what might b e a reasonable result class for a given pair of
argument classes For the purp ose of de ning the b ehaviour
z A numb er
of this function the numb er classes are considered to form a
tower as follows
A Result
complex
complex ratio log returns the logarithm of z to the base of the natural log
complex integer arithms log returns the logarithm of z to base log
float returns the logarithm of z to base The result can b e
ratio either float or complex Metho ds are de ned for the ap
integer propriate sub classes of integer and float and for ratio
and complex The metho ds for integer and ratio co erce
their argument to float and then compute the result The
where the classes corresp ond to and approximate the ab
metho ds for float pro duce a float result when z is real
stract mathematical ob jects C Q i Z i R Q Z For each
and p ositive otherwise a complex result The metho ds for
argument class combination the entry in Table A shows
complex pro duce a complex result
the lowest class in which the result might b e expressed In
this sense we de ne the lower b ound class in which the result
can o ccur for a given pair of arguments The result of expt
should b e in the lowest class p ossible for a given argument
A sqrt generic function
combination without loss of information
A Arguments
A sinh generic function
z A numb er
sqrt returns the principal square ro ot of z
A cosh generic function
A sqrt method
A tanh generic function
A Arguments
A asinh generic function
integer An integer
A acosh generic function
A Result
The metho d for integer returns an integer if the argument is
A atanh generic function
a p ositive p erfect square a gaussian integer if the argument
is a negative p erfect square otherwise a float is returned
if the argument is p ositive or a complex if the argument is
A Arguments
negative
z A numb er
A sqrt method
A Result
These functions compute the hyp erb olic sine cosine tan
A Arguments
gent arc sine arc cosine and arc tangent functions The
result can b e float or complex Metho ds are de ned for the
double oat A double oat
appropriate sub classes of integer and float and for ration
and complex The metho ds for integer and rational co erce
their argument to float and then compute the result For
A Result
the sine cosine tangent and arc sine the metho ds for float
The metho d for double float returns a double float if the
pro duce a float result For the arc cosine the metho d for
argument is non negative and a complex if it is not
float pro duces a float if z otherwise a complex For
the arc tangent the metho d for float pro duces a float if
z otherwise a complex
A expt generic function
All metho ds pro duce a complex result for a complex argu
ment
A Arguments
NOTE more detailed speci cation is required for this
z z Two numb ers
1 2
library module in particular with respect to the han
Programming Language EuLisp version
Table A expt result classes
Base Exp onent Class
Class integer ratio float complex
integer integer integer float complex
ratio integer integer float complex
float float float float complex
complex integer integer integer complex complex
complex ratio integer integer complex complex
complex complex complex complex complex
d ling of negative and the stating of branches and A Formatted IO
cuts
The de ned name of this mo dule is formatted io
A scan mismatch stream condition
A Init options
format string string The value of this option is the for
mat 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 includin g the ob ject that caused
the condition to b e signaled
A Remarks
This condition is signaled by scan if the format string do es
not agree with the data received from stream
A scan function
A Arguments
format string A string containing format directives
stream A stream from which input is to b e taken
A Result
Returns a list of ob jects which have b een read
A Remarks
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 campatible with the sp eci ed directive The second
optional argument sp eci es a stream from which to take in
put If stream is not supplied input is taken from the stream
which is the value of calling standard input stream Scan
returns a list of the values read in
a any accept any ob ject
b binary an integer in binary format
c character a single character
d decimal an integer decimal format
Programming Language EuLisp version
m ne a xed format oating p oint numb er in FOR nr radix the integer argument is output in radix n
TRAN E format
s s expression uses write to output the ob ject
m nf an exp onential format oating p oint numb er
in FORTRAN F format t tab output su cient spaces to reach the next
tab stop
m ng a generalized oating p oint numb er in either
xed or exp onential format either xed format or exp o x hexadecimal the integer argument is output in
nential notation as appropriate hexadecimal format
o o ctal an integer in o ctal format newline output a newline character
conditional newline output a newline charac
r radix an integer in sp eci ed radix format
ter if it cannot b e determined that the output stream is
at the b eginning of a fresh line
x hexadecimal an integer in hexadecimal format
page separator output a page separator
newline matches a newline character in the
input
tilde output a tilde
A format function
A Arguments
stream One of t or an instance of stream
format string A string containing format directives
obj
A Result
Returns a list of unconsumed objs
A Remarks
Has side e ect of printing according to format string If
stream 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 exception of those pre xed by tilde
graphic representation as follows
a any use prin to output the ob ject
b binary the integer argument is output in binary
format
c character the next argument is displayed as a
character
d decimal the integer argument is output in deci
mal format
m ne xed format oating p oint the oating p oint
argument is output in FORTRAN E format
m nf exp onential oating p oint the oating p oint
argument is output in FORTRAN F format
m ng generalized oating p oint output the
oating p oint argument using either xed format or ex
p onential notation as appropriate
o o ctal the integer argument is output in o ctal
format
Programming Language EuLisp version
A The empty list A Remarks
Output the external representation of the empty list on
The de ned name of this mo dule is null The empty list is
stream as describ ed ab ove
disjoint from the class pair The combination of null
and pair allows the creation of prop er lists since a prop er
list is one whose last pair contains the empty list in its cdr
eld
A syntax
A Remarks
The empty list which is the only instance of the class null
has as its external representation an op en parenthesis fol
lowed by a close parenthesis The empty list is also used to
denote the b o olean value false
A null class
The class whose only instance is the empty list denoted
A null function
A Arguments
obj Ob ject to examine
A Result
Returns t if obj is the empty list otherwise
A length method
A Arguments
nul l The empty list
A Result
Returns zero
A generic prin method
A generic write method
A Arguments
nul l The empty list
stream The stream on which the representation is to b e
output
A Result
The empty list
Programming Language EuLisp version
A Numb ers
A floatp function
The de ned name of this mo dule is number The naming
conventions describ ed in section are applied in the following
de nitions A Arguments
Numb ers can take on many forms with unusual prop erties obj Ob ject to examine
sp ecialized for di erent tasks but two classes of numb er nor
mally su ce for the ma jority of needs Thus at level only
A Result
a limited set of numb er classes are de ned
If the class of obj is a sub class of float the result is obj
In Figure A is an example of what the initial numb er class
otherwise
hierarchy for level might lo ok like The inheritance rela
tionships by this diagram are part of this de nition but it
is not de ned whether they are direct or not For example
A arithmetic condition condition
integer and float are not necessarily direct sub classes of
number and the class of each numb er class might b e a sub
class of number class Since there are only two concrete
A Init options
numb er classes at level co ercion is simple as shown in g
ure A Any level version of a library mo dule for example
operator object The op erator which signalled the con
elementary functions need only de ne metho ds for these
dition
two classes
operand list list The op erands passed to the op erator
A number class
A Remarks
This is the general condition class for conditions arising from
The abstract class which is the sup erclass of all numb er
arithmetic op erations
classes
A equal method
A numberp function
A Arguments
A Arguments
number an instance of number
1
obj Ob ject to examine
number an instance of number
2
A Result
If the class of obj is a sub class of number the result is obj
A Result
otherwise
If the class of number and number is the same sub class of
1 2
number the result of equal is the result of If the instances
are not of the same sub class of number the result is
A integer class
The abstract class which is the sup erclass of all integer num
A function
b ers
A Arguments
A integerp function
z z A sequence of instances of number
1 2
A Arguments
A Result
obj Ob ject to examine
Computes the sum of the arguments using the generic func
tion binary plus Given zero arguments returns of
class integer One argument returns that argument The
A Result
arguments are combined left asso ciatively
If the class of obj is a sub class of integer the result is obj
otherwise
A function
A float class
A Arguments
The abstract class which is the sup erclass of all oating p oint
z z A non empty sequence of instances of number
1 2
numb ers
Programming Language EuLisp version
Figure A Level numb er class hierarchy and co ercion chart
number number class single precision integer
float number class double float
double float number class
integer number class
single precision integer number class
A Result A Result
Determines whether the sequence of numb ers x up to
Computes the result of subtracting successive arguments 1
x is strictly decreasing according to the generic function
from the second to the last from the rst using the generic
n
binary lt
function binary difference Zero arguments is an error
One argument returns the negation of the argument The
arguments are combined left asso ciativel y
A function
A function
A Arguments
x x A sequence of at least two instances of number
1 2
A Arguments
z z A sequence of instances of number
1 2
A Result
Determines whether the sequence of numb ers x up to x is
1 n
increasing according to the generic function binary le
A Result
Computes the pro duct of the arguments using the generic
function binary times Given zero arguments returns
A function
of class integer One argument returns that argument The
arguments are combined left asso ciativel y
A Arguments
A function
x x A sequence of at least two instances of number
1 2
A Result
A Arguments
Determines whether the sequence of numb ers x up to x is
1 n
z z A non empty sequence of instances of number
1 2
decreasing according to the generic function binary ge
A Result
A max function
Computes the result of dividin g the rst argument
by its succeeding arguments using the generic function
binary divide Zero arguments is an error One argument
A Arguments
computes the recipro cal of the argument
x x A non empty sequence of instances of
1 2
number
A function
A Result
Determines the maximal element of the numb ers x up to
1
A Arguments
x using the generic function binary lt Zero arguments is
n
an error One argument returns x
1
x x A sequence of at least two instances of number
1 2
A Result
A min function
Determines whether the sequence of numb ers x up to
1
x is strictly increasing according to the generic function
n
A Arguments
binary lt
x x A non empty sequence of instances of
1 2
number
A function
A Result
A Arguments
Determines the minimal element of the numb ers x up to x
1 n
using the generic function binary lt Zero arguments is an
x x A sequence of at least two instances of number
1 2
error One argument returns x
1
Programming Language EuLisp version
A gcd generic function A positivep generic function
A Arguments
A Arguments
x An instance of number
z z A non empty sequence of instances of num
1 2
b er
A Result
Compares x against the zero element of the class of x using
A Result
the generic function binary lt
Computes the greatest common divisor of z up to z using
1 n
the generic function binary gcd Zero arguments is an error
One argument returns z
1
A negativep generic function
A lcm generic function
A Arguments
x An instance of number
A Arguments
q q A non empty sequence of instances of
1 2
A Result
number
Compares x against the zero element of the class of x using
the generic function binary lt
A Result
Computes the least common multiple of q up to q using
1 n
A binary plus generic function
the generic function binary lcm Zero arguments is an error
One argument returns q
1
A Arguments
z z Two instances of number
A abs generic function
1 2
A Result
A Arguments
Compute the sum of z and z
1 2
z An instance of number
A binary difference generic function
A Result
Compute the absolute value of z
A Arguments
z z Two instances of number
1 2
A zerop generic function
A Result
A Arguments
Compute the di erence of z and z
1 2
x An instance of number
A negate generic function
A Result
Compares z with the zero element of the class of z using the
A Arguments
generic function
z An instance of number
A signum generic function
A Result
Compute the additive inverse of x
A Arguments
x An instance of number
A binary times generic function
A Result
A Arguments
If zerop x then returns x Otherwise returns the result of
z z Two instances of number
converting to the class of x with the sign of x
1 2
Programming Language EuLisp version
A Result A Pairs and Lists
Compute the pro duct of z and z
1 2
The de ned name of this mo dule is pair
A binary divide generic function
A pair syntax
A Arguments
A pair is written as obj obj where obj is the car and
1 2 1
obj is the cdr There are two sp ecial cases in the print
2
z z Two instances of number
1 2
representation of pair If obj is the empty list then the
2
pair is written as obj If obj is an instance of pair
1 2
A Result
then the pair is written as obj obj obj where obj
1 3 4 3
is the car of obj and obj is the cdr with the ab ove rule
2 4
Compute the ratio of z and z If the divisor is the
1 2
for the empty list applying By induction a list of length
zero element of the class an error is signaled condition
n is written as obj obj obj with the ab ove rule
1 n 1 n
division by zero
for the empty list applying The representations of obj and
1
obj are determined by the external representations de ned
2
in other sections of this de nition see character A
A binary lt generic function
double float A null A spint A
string A symbol A and vector A as
well as instances of pair itself The syntax for the external
A Arguments
representation of pairs and lists is de ned in Table A
x x Two instances of number
1 2
A pair class
A Result
Compare x with x returning t if x precedes x according
1 2 1 2
The class of all instances of pair Instances of the class
to the ordering metho d of the class of higher class of x and
1
pair also known informally as a dotted pair is a tuple
x
2
whose slots are called for historical reasons car and cdr
Pairs are created by the function cons and the slots are ac
cessed by the functions car and cdr The ma jor use of pairs
A binary gcd generic function
is in the construction of prop er lists A prop er list is de
ned as either the empty list denoted by or a pair whose
cdr is a prop er list An improp er list is one containing a cdr
A Arguments
which is not a list see Table A
q q Two instances of number
1 2
A consp function
A Result
Compute the greatest common divisor of q and q
1 2
A Arguments
obj Ob ject to examine
A binary lcm generic function
A Result
A Arguments
Returns obj if obj is a sub class of pair otherwise
q q Two instances of number
1 2
A atom function
A Result
Compute the lowest common multiple of q and q
1 2
A Arguments
obj Ob ject to examine
A Result
If obj is not an instance pair obj is returned otherwise
A cons function
A Arguments
Programming Language EuLisp version
Table A Pair and List Syntax
pair pair begin obj pair separator obj pair end
1 2
pair begin
pair separator whitespace whitespace
pair end
list empty list j list head
empty list
list head pair begin obj list tail
1 1
list tail improper tail j pair end j obj list tail
i i i i+1
improper tail pair separator obj
i i
obj An ob ject to b e stored in the car eld of the result A Remarks
1
pair
Note that if obj is not then the use of setter cdr will
make pair an improp er list It is an error to apply these
obj An ob ject to b e stored in the cdr eld of the result
2
setter functions to anything other than a pair
pair
A converter string method
A Result
Allo cates a new pair initiali zed to obj and obj
1 2
A Arguments
pair A list of characters
A car function
A Result
Constructs and returns a string the characters of which cor
A cdr function
resp ond to the characters comprising the rst elements of the
top level pairs of the instance of pair It is an error if the
source is not a prop er list An error is signaled condition
A Arguments
not a character unless all of those elements are instances
of the class character
pair An instance of pair
A not a character conversion condition
A Result
Given an instance of pair such as the result of cons obj
1
A Init options
obj the function car returns obj and cdr returns obj
2 1 2
source list The list of ob jects to b e converted into a
string
A Remarks
It is an error to apply car or cdr functions to anything other
A Remarks
than a pair The empty list written is not a pair car
and cdr is an error
Signalled by the pair metho d of converter string unless
the source list contains only characters
A setter car setter
A converter string method
A setter cdr setter
A Arguments
pair A list of characters
A Arguments
pair An instance of pair
A Result
Constructs and returns a vector the elements of which corre
obj An ob ject
sp ond to rst elements of the top level pairs in the instance
of pair It is an error if the source is not a prop er list
A Result
Given an instance of pair such as the result of cons obj
1
A equal method
obj the function setter car replaces obj with obj and
2 1
setter cdr replaces obj with obj The setter functions
2
A Arguments return obj
Programming Language EuLisp version
pair an instance of pair
1
A copy alist function
pair an instance of pair
2
A Arguments
A Result
alist A prop er list of pairs
The result is the conjunction of the pairwise applicatio n of
equal to the car elds and the cdr elds of the arguments
A Result
Constructs and returns a copy of the list alist copying b oth
the top level pairs and the second level pairs the asso cia
A copy method
tions
A Arguments
A copy list function
pair A pair
A Arguments
A Result
list A list prop er or improp er
Constructs and returns an instance of pair whose elements
are the same as those of the source under eql so that the
resulting pair is the same under equal as the source
A Result
Constructs and returns a copy of list by copying the top level
pairs only
A list function
A copy tree function
A Arguments
obj obj A sequence of ob jects
1 n
A Arguments
list A list prop er or improp er
A Result
Allo cates a set of pairs each of which has b een initiali zed with
A Result
obj in the car eld and the pair whose car eld contains
i
Constructs and returns a copy of list by copying the top level
obj in the cdr eld Returns the pair whose car eld
i+1
pairs and then op erates recursively on each of those pairs
contains obj
1
thus copying every pair in list
A length method
A generic prin method
A Arguments
A generic write method
pair A pair
A Arguments
A Result
pair The pair to b e output on stream
Returns the count of the numb er of top level pairs in list
stream The stream on which the representation is to b e
output
A Remarks
The list need not b e a prop er list
A Result
The pair supplied as the rst argument
A Examples
A Remarks
Output the external representation of pair on stream as de
scrib ed in the intro duction to this section Both metho ds
length result is
call the generic function again to pro duce the external rep
length cons result is
resentation of the car and cdr slots of the pair
length cons result is
length cons cons result is
Programming Language EuLisp version
Table A Metho ds for single precision integers
A Result
Returns obj if obj is an instance of spint
binary plus
binary difference
negate
binary times
A evenp generic function
binary lt
binary gcd
A Arguments
binary lcm
abs
number An instance of number
zerop
signum
positivep
A Result
negativep
If number is an instance of a suitable sub class of number
returns t if the remainder from dividing i by two is zero
otherwise
A Single Precision Integers
The de ned name of this mo dule is spint
A evenp method
A single precision integer syntax A Remarks
Implements evenp for single precision integers
A p ositive integer is has its external representation as a se
quence of digits optionally preceded by a plus sign A nega
A oddp generic function
tive integer is written as a sequence of digits preceded by a
minus sign For example
A Arguments
Integer literals have an external representation in any base
up to base For convenience base base and base
number An instance of number
have distinguis hed notations b o and x resp ectively
For example b o and x d all
denote the same value
A Result
If number is an instance of a suitable sub class of number
The general notation for an arbitrary base is base r where
returns t if the remainder from dividing i by two is non
base is an unsigned decimal numb er Thus the ab ove ex
zero otherwise
amples may also b e written r r
r r d or rya The syntax for the external
representation of integer literals is de ned in Table A
A oddp method
NOTE At present this do cument do es not de ne a class inte
ger with variable precision It is planned this should app ear in a
future version at level of the language The class will b e named
Implements oddp for single precision integer
variable precision integer with the shorter alias vpint The
syntax given here is applicable to b oth single and variable preci
sion integers
A division by zero arithmetic condition
The class is named single precision integer but it is
also called by the shorter alias spint Arithmetic op era
Signalled by any of quotient remainder and modulo if their
tions for single precision integer are de ned by metho ds
second argument is zero
to b e attached to the generic functions listed in Table A
A quotient generic function
A single precision integer class
A Arguments
The class of all instances of single precision integers Also
named spint
integer integer Two instances of integer
1 2
A Result
A single precision integer p function
If number is an instance of a suitable sub class of number
returns q by solving the equation number number q r
1 2
A Arguments
where r lies b etween zero inclusive and the number
2
sig n number exclusive Sign combination for quotient
1
obj Ob ject to examine
is as follows
Programming Language EuLisp version
Table A Integer Syntax
integer sign uinteger
sign f j g
uinteger ubinary j uoctal j udecimal j uhexadecimal j uinteger with base
+
ubinary extension fb j Bg digit
+
uoctal extension fo j Og digit
+
udecimal digit
+
uhexadecimal extension fx j Xg digit
+
uinteger with base extension udecimal fr j Rg digit udecimal
digit f j g
digit f j j g
digit f j j j fa j Agg
digit f j j j fa j Ag j j fy j Ygg
digit f j j j fa j Ag j j fy j Yg j fz j Zgg
integ er integ er
2 2
A Arguments
integ er q q
1
i i Two instances of integer
integ er q q
1 2
1
A Result
A quotient method
If i is an instance of a suitable sub class of integer returns
m by solving the equation integ er integ er q r
1 2
A Remarks
where r lies b etween zero inclusive and the integ er
2
sig n integ er exclusive and m is constrained by m
Implements quotient for single precision integer An error is
1
jq j Sign combination for modulo is given in Table A
signalled condition division by zero if integer is zero
2
A remainder generic function
A modulo method
A Remarks
i i i
1 2
Implements modulo for single precision integer An error is
signalled condition division by zero if integer is zero
2
A Arguments
integer integer Two instances of integer
1 2
A most positive single precision integer
single precision integer
A Result
If integer is an instance of a suitable sub class of integer
A Remarks
returns r by solving the equation integ er integ er q
1 2
r where r lies b etween zero inclusive and the integ er
2
This is an implementation d e ned constant A conform
sig n integ er exclusive Sign combination for remainder
1
ing pro cessor must supp ort a value greater than or equal
is as follows
to and greater than or equal to the value of
maximum vector index
integ er integ er
2 2
integ er r r
1
integ er r r
1
A most negative single precision integer
single precision integer
A remainder method
A Remarks
This is an implementation de ned constant A conforming
A Remarks
pro cessor must supp ort a value less than or equal to
Implements remainder for single precision integer An er
ror is signalled condition division by zero if integer is
2
zero
A converter character method
A modulo generic function
A Arguments
single precision integer A single precisi on i nteger
i i i
1 2
Programming Language EuLisp version
Table A Sign combination in modulo
integ er integ er
2 2
integ er r remainder i remainder i i i
1 2 1 2 2
integ er remainder i remainder i i i r
1 2 1 2 2
A Result
A generic prin method
Returns an instance of character whose p osition in the
default character set corresp onds to that sp eci ed by the
instance of integer An error is signaled condition
A generic write method
cannot convert to character if the sp eci ed p osition
do es not exist
A Arguments
A no such character conversion condition
i The single precision integer to b e output on stream
stream The stream on which the representation is to b e
Signalled by the conversion metho d from spint to
output
character if there is no character in the defaul character
set corresp onding to the p osition sp eci ed by the integer
A Result
The single precision integer supplied as the rst argument A See also converter character
A Remarks
A converter string method
Output external representation of i on stream in decimal as
describ ed in the intro duction to this section
A Arguments
single precision integer A single precisi on i nteger
A Result
Constructs and returns a string the characters of which cor
resp ond to the external representation of the instance of
single precision integer in decimal
A converter double float method
A Arguments
single precision integer A single precision integer
A Result
Returns an instance of double float whose value is the
oating p oint approximation to the single precision integer
source
A copy method
A Arguments
single precision integer A single precision integer
A Result
Constructs and returns
an instance of single precision integer whose value is
the same under as the source
Programming Language EuLisp version
Table A Initial stream class hiearchy
A file streamp function
stream stream class
file stream stream
stream properties stream properties class
A Arguments
stream direction stream properties
input stream
obj ob ject to examine
output stream
io stream
stream unit stream properties
A Result
The supplied argument if it is an instance of file stream
stream positionable p stream properties
otherwise
A Streams
A stream condition condition
The de ned name of this mo dule is stream
This is the general condition class for conditions arising from
op erations on streams
A stream class
A syntax error condition
The abstract class of all instances of stream
This is the general condition class for conditions arising from
The initial class hiearchy of streams and stream prop erties
using the function read
is shown in Table A
A input stream p function
A file stream class
The class of all instances of file stream This is the only
A Arguments
sub class of stream de ned at level
obj Ob ject to examine
A Init options
A Result
direction direction An instance of
The supplied argument if one of its stream direction is an
stream direction
instance of input stream otherwise
transaction unit unit An instance of stream unit
or character indicating a character stream or
A output stream p function
spint indicating a binary stream
positionable boolean Either or non
A Arguments
obj Ob ject to examine
A input stream stream direction
A Result
Used to indicate stream direction when making instances of
The supplied argument if one of its stream direction is an
file stream
instance of output stream otherwise
A io stream stream direction
A io stream p function
Used to indicate stream direction when making instances of
A Arguments
file stream
obj Ob ject to examine
A ouput stream stream direction
A Result
Used to indicate stream direction when making instances of The supplied argument if one of its stream direction is an
file stream instance of output stream otherwise
Programming Language EuLisp version
A Result
A character stream p function
A stream
NOTE version In a future version it is forseen that a
A Arguments
more general approach to le naming will b e adopted such as the
pathnames of Common Lisp At that time it will b e appropriate
to add another metho d to open where the hand le argument is
obj Ob ject to examine
an instance of pathname Thus at present no implementation
indep endent way of naming les is provided
A Result
The supplied argument if one of its prop erties is an instance
A open p generic function
of character stream otherwise
A Generic Arguments
A binary stream p function
stream stream A stream
A Arguments
A Result
A non value if stream is op en otherwise
obj Ob ject to examine
A open p method
A Result
The supplied argument if one of its prop erties is an instance
A Sp ecialized Arguments
of binary stream otherwise
stream file stream A le stream
A open generic function
A Result
A non value if stream is op en otherwise
A Generic Arguments
stream stream The stream to b e op ened
A close generic function
hand le object The name of the ob ject internal or
external to the pro cessor
A Generic Arguments
initlist list A list of initiali zati on options
stream stream A stream
A Result
A Result
If stream is op en it is closed Returns
A stream
A close method
A open method
A Sp ecialized Arguments
A Sp ecialized Arguments
stream file stream A le stream
stream file stream The stream to b e op ened
hand le string The name of the le to b e op enend
A Result
If stream is op en it is closed Returns
initlist list A list of initiali zati on options as fol
lows
A write unit generic function
direction direction An instance of
stream direction
A Generic Arguments
transaction unit unit An instance of
stream unit
stream stream A stream
positionable boolean Either or non
object object An ob ject
Programming Language EuLisp version
A Result
A prin function
The object is written to stream Returns
A Arguments
A write unit method
object
A Sp ecialized Arguments
stream
stream file stream A le stream
A Result
character character A character
If stream is op en object is output on stream
A Result
A generic prin generic function
If the transaction unit of stream is character the char
acter is written to stream Returns
A Generic Arguments
A write unit method
stream stream The stream on which object is to b e
output
A Sp ecialized Arguments
object object The ob ject to b e output on stream
stream file stream A le stream
A Result
integer spint A single precision integer
If stream is op en object is output on stream
A Result
A See also Sections on the di erent classes de
If the transaction unit of stream is spint the integer is
ned at level for metho ds o on this function
written to stream Returns
A read unit generic function
A write function
A Generic Arguments
A Arguments
stream stream A stream
object
A Result
stream
The next ob ject input from stream The class of the ob ject
is restricted to that of the transaction unit of the stream
A Result
If stream is op en object is output on stream
A read unit method
A Sp ecialized Arguments
A generic write generic function
stream file stream A le stream
A Generic Arguments
A Result
stream stream The stream on which object is to b e
output
An ob ject representing the next transaction unit input from
stream The class of this ob ject is determined by the trans
object object The ob ject to b e output on stream
action unit prop erty of stream
A Result
A read function
If stream is op en object is output on stream
A Arguments
A See also Sections on the di erent classes de
stream An instance of stream
ned at level for metho ds o on this function
Programming Language EuLisp version
A Result
A flush generic function
An ob ject corresp onding to the next element pro cessed by
read from stream
A Generic Arguments
A Remarks
stream stream A stream
When a syntax error is detected an error is signaled condi
tion syntax error The p osition of the stream b eing read
is unde ned after such an error o ccurs
A Result
Any remaining bu ered output to stream is forced out
A generic read generic function
A flush method
A Generic Arguments
A Sp ecialized Arguments
stream stream A stream
stream file stream A le stream
prototype object An ob ject
A Result
A Result
Any remaining bu ered output to stream is forced out
The next ob ject input from stream
A wait method
A generic read method
A Sp ecialized Arguments
A Sp ecialized Arguments
stream file stream The file stream on which
to wait
stream file stream A le stream
timeout object The timeout p erio d
prototype object An ob ject
A Result
A Result
Returns stream if stream is an input stream or an io stream
and has input available
The next ob ject input from stream What is protptype for
A See also wait
A peek unit generic function
A Generic Arguments
stream stream A stream
A Result
The next ob ject that could b e input from stream The class
of the ob ject is restricted to that of the transaction unit of
the stream
A peek unit method
A Sp ecialized Arguments
stream file stream A le stream
A Result
An ob ject representing the next transaction unit that o culd
b e input from stream The class of this ob ject is determined
by the transaction unit prop erty of stream
Programming Language EuLisp version
Table A Examples of string literals
A Strings
Example Contents
The de ned name of this mo dule is string
a nb a newline and b
c c and
x x followed by space
xabcde xabcd followed by e
A string syntax
x x x followed by x
x x followed by
xabcg xabc followed by g
String literals are delimited by the string begin and string
x abc xab followed by c
end glyphs which are b oth de ned as the glyph called quo
tation mark For example abcd
Sometimes it might b e desirable to include string delimiter
characters in strings The aim of escaping in strings is to ful
A string class
ll this need The string escape glyph is de ned as reverse
solidus String escaping can also b e used to include cer
tain other characters that would otherwise b e di cult to de
The class of all instances of string
note The set of named sp ecial characters see section A
have a particular syntax to allow their app earance in strings
A Init options
To allow arbitrary characters to app ear in strings the argu
ment to the hex insertion digram is an integer denoting the
size spint The numb er of characters in the string
p osition of the character in the current character set In the
Strings are zero based and thus the maximum index is
case of hex insertion each d denotes any hexadecimal digit
size If not supplied the size is zero
A summary of string escape digrams app ears in Table A
Some examples of string literals app ear in Table A
fill character A character with which to initial ize the
string If not supplied the ll character is x
Table A String escap e digrams
Digram Interpretation
A stringp function
a alert
b backspace
d delete
A Arguments
f formfeed
l linefeed
obj Ob ject to examine
n new line
r return
t tab
A Result
v vertical tab
Returns obj if obj is an instance of a sub class string other
string begin
wise
string end
string escape
xdddd hex insertion
A string ref function
The syntax for the external representation of strings is de
ned in Table A
A setter string ref setter
NOTE At present this do cument refers to the current char
acter set but de nes no means of selecting alternative character
A Arguments
sets This is to allow for future extensions and implementation
de ned extensions which supp ort more than one character set
string Source string
The function write outputs a re readable form of any es
n An instance of single precision integer
cap ed characters in the string For example a n b input
notation is the string containing the characters newline
character An instance of character for setter
a and b The function write pro duces a n b
whilst prin pro duces
A Result
a
Access and up date elements of a string It is an error if n
b
is outside the range zero to one less than the length of the
string
Characters which do not have a glyph asso ciated with their
p osition in the character set are output as a hex insertion
in which all four hex digits are sp eci ed even if there are
A converter pair method
leading zeros The function prin outputs the interpretation
of the characters according to the de nitions in section A
A Sp ecialized Arguments and omits the string begin and string end characters
Programming Language EuLisp version
Table A String Syntax
string string begin string char string end
string begin
string char normal char j escape diphthong
string end
normal char any character begin end or escape excepted
escape diphthong string escape string insertion
string escape
string insertion string begin j string end j string escape j hex insertion j string new line
hex insertion string hex digit digit digit digit
string new line n j N
string hex x j X
string string A string to b e converted to a list of
characters
A string lt function
A Result
A Arguments
Constructs and returns a prop er list of characters the ele
string string Two instances of string
1 2
ments of which corresp ond to the characters in the external
representation of the instance of string as would b e gener
ated by write
A Result
If the sequence of characters in string is alphab etical l y less
1
than that in string returns t else
2
A equal method
A string slice function
A Sp ecialized Arguments
string string an instance of string
1
A Arguments
string string an instance of string
2
string An instance of string
start An instance of single precision integer
A Result
If the length of each instance of string is the same then the
An instance of single precision integer
result is the conjunction of the pairwise application of equal
to the elements of the arguments If not the result is
A Result
Returns a newly allo cated string containing the characters
of string starting at start up to end
A copy method
A Sp ecialized Arguments
A string append function
string string A string
A Arguments
string string Two instances of string
A Result
1 2
Constructs and returns an instance of string whose char
acters are the same as the source and such that the resulting
A Result
string is the same under equal as the source
Returns a newly allo cated string containing the characters
of string followed by the characters of string
1 2
A length method
A generic prin method
A Sp ecialized Arguments
A Sp ecialized Arguments
string string An instance of string
string string String to b e ouptut on stream
A Result
stream stream Stream on which string is to b e oup
Returns the numb er of characters in string
tut
Programming Language EuLisp version
A Result A Symb ols
The string string
The de ned name of this mo dule is symbol
Output external representation of string on stream as de
scrib ed in the intro duction to this section interpreting each
of the characters in the string The op ening and closing quo
A symbol syntax
tation marks are not output
The syntax of symb ols also serves as the syntax for identi
ers Identi ers in EULISP are very similar lexically to iden
A generic write method
ti ers in other Lisps and in other programming languages
Informally an identi er is a sequence of alphabetic digit and
other characters starting with a character that is not a digit
A Sp ecialized Arguments
Characters which are special see section A must b e es
cap ed if they are to b e used in the names of identi ers
string string String to b e ouptut on stream
However b ecause the common notations for arithmetic op er
ations are the glyphs for plus and minus have another
stream stream Stream on which string is to b e oup
use to indicate the sign of a numb er these glyphs are classi
tut
ed as identi ers in their own right as well as b eing part of
the syntax of a numb er
A Result
Sometimes it might b e desirable to incorp orate characters
The string string
in an identi er that are normally not legal constituents The
aim of escaping in identi ers is to change the meaning of
Output external representation of string on stream as de
particular characters so that they can app ear where they are
scrib ed in the intro duction to this section replacing single
otherwise illegal Identi ers containing characters that are
characters with escap e sequences if necessary Op ening and
not ordinarily legal constituents can b e written by delimiting
closing quotation marks are output
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 escapes For example
is the identi er whose name contains the three characters
and and a 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 escapes
Any identi er can b e used as a literal in which cases it de
notes a symbol Because there are two escaping mechanisms
and b ecause the rst character of a token a ects the inter
pretation of the remainder there are many ways in which to
input the same identi er If this identi er is used as a literal
the results of pro cessing each token denoting the identi er
will b e eq to one another For example the following tokens
all denote the same symb ol
which will b e output by 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 symb ols For example a b and abc def are two sym
b ols as output by write such that read can read them as
two symb 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 symb ol a followed by the start of a list the
symb ol b and the symb ol abc def
The syntax of the external representation of identi ers and
Programming Language EuLisp version
Table A Identi er Symb ol Syntax
symbol identi er
identi er normal identi er j peculiar identi er
normal identi er non digit constituent
peculiar identi er sign identi er j point identi er
sign identi er fsign j sign fnon digit j sign j pointgg constituent
point identi er point fnon digit j sign j pointg constituent
constituent non digit j digit j sign j point
alphanumeric alphabetic j digit
non digit alphabetic j other j escaped
escaped single escaped j multiple escaped
multiple escaped multiple escape fsingle escaped j non escapeg multiple escape
single escaped single escape fany characterg
non escape not single escape multiple escape
multiple escape
single escape
point
A Result symb ols is de ned in Table A
Returns a string which is equal to that given as the argument
to the call to make symbol which created symbol
A symbol class
A symbol exists p function
The class of all instances of symbol
A Arguments
A Init options
string A string containing the characters to b e used to
string string The string containing the characters to b e
determine the existence of a symb ol with that name
used to name the symb ol
A Result
A symbolp function
Returns the symb ol whose name is string if that symb ol has
already b een constructed by make symbol Otherwise re
turns
A Arguments
obj Ob ject to examine
A generic prin method
A Result
A generic write method
Returns obj if obj is an instance of a sub class of symbol
A Sp ecialized Arguments
A gensym function
symbol symbol The symb ol to b e output on stream
A Arguments
stream stream The stream on which the represen
tation is to b e output
string A string contain characters to b e prep ended to
the name of the new symb ol
A Result
The symb ol supplied as the rst argument
A Result
Makes a new symb ol with a name generated by a pro cessor
de ned mechanism Optionally a pre x string for this name
A Remarks
may b e sp eci ed
Outputs the external representation of symbol on stream as
describ ed in the intro duction to this section interpreting
each of the characters in the name
A symbol name function
A generic write method
A Arguments
symbol An instance of symbol
A Sp ecialized Arguments
Programming Language EuLisp version
A Tables symbol symbol The symb ol to b e output on stream
stream stream The stream on which the represen
The de ned name of this mo dule is table Tables provide a
tation is to b e output
general key to value asso ciation mechanism
A Result
A table class
The symb ol supplied as the rst argument
The class of all instances of table
A Remarks
Outputs the external representation of symbol on stream as
A Init options
describ ed in the intro duction to this section If any charac
ters in the name would not normally b e legal constituents of
comparator function The function to b e used to com
an identi er or symb ol the output is preceded and succeeded
pare keys
by multiple escap e characters
A tablep function
A Arguments
obj Ob ject to examine
A Result
Returns obj is obj is an instance of table
A table ref function
A Arguments
table An instance of table
key An ob ject to b e used to identify an entry in the
table
no entry value An ob ject to b e returned in the case
that key is not found
A Result
If key is in table matched by the comparator function then
the asso ciated value is returned If key is not in table the
value is returned However if the optional parameter
no entry value is provided and key is not in table the value
no entry value is returned
A setter table ref setter
A Arguments
table An instance of table
key An ob ject to b e used to identify an entry new or
existing in the table
value An ob ject to b e asso ciated with key in table
A Result
If key do es not o ccur in table a new entry is made asso ciating
key and value If key do es o ccur then the asso ciation is
changed to value value obj is returned
Programming Language EuLisp version
Table A Vector Syntax
A table delete function
vector extension vector begin obj vector end
extension
vector begin
A Arguments
vector end
table An instance of table
key An ob ject to b e used to identify an entry new or
A Vectors
existing in the table
The de ned name of this mo dule is vector
A Result
If key o ccurs in table b oth the key and its asso ciated value
A vector syntax
are deleted from the table If key do es not o ccur in table no
action is taken
A vector is written as obj obj For example
1 n
is a vector of three elements the integers
A generic prin method
and The representations of obj are determined by the
i
external representations de ned in other sections of this
de nition see character A double float A
A generic write method
null A pair A spint A string A
and symbol A as well as instances of vector itself
The syntax for the external representation of vectors is de
A Arguments
ned in Table A
table The table to b e output on stream
A vector class
stream The stream on which the representation is to b e
output
The class of all instances of vector
A Result
The table supplied as the rst argument
A Init options
size spint The numb er of elements in the vector Vec
A Remarks
tors are zero based and thus the maximum index is size
Output the external representation of table on stream
If not supplied the size is zero
The external representation of instances of table is
implementation de ned
fill object An ob ject with which to initial ize the string
If not supplied the ll ob ject is
A vectorp function
A Arguments
obj Ob ject to examine
A Result
Returns obj if obj is an instance of vector
A length method
A Arguments
vector A vector
A Result
Returns the length of vector which is the maximum index
plus one
Programming Language EuLisp version
A Result
A vector ref function
If the maximum index of each instance of vector is the same
under then the result is the conjunction of the pairwise
application of equal to the elements of the arguments If
not the result is
A setter vector ref setter
A Arguments
A copy method
vector A vector
A Arguments
n An integer to sp ecify the index of an element in the
vector
vector A vector
obj An ob ject to b e stored as element n of vector
A Result
Constructs and returns an instance of vector whose ele
A Result
ments are the same as those of the source under eql so
The accessor returns and the up dator changes the contents
that the resulting vector is the same under equal as the
of the nth index of vector The value stored in index p osition
source
n is obj which is returned
A generic prin method
A make initialized vector function
A generic write method
A Arguments
obj obj obj A sequence of ob jects
A Arguments
1 2 n
vector the vector to b e ouptut on stream
A Result
stream the stream on which the representation is to b e
Allo cate a vector of size n and store obj in vector ref
1
output
v obj in p osition vector ref v up to obj in
2 n
vector ref v n Returns the initialized vector
A Result
The vector supplied as the rst argument
A maximum vector index integer
A Remarks
A Remarks
Output the external representation of pair on stream as de
This is an implementation de ned constant A conforming
scrib ed in the intro duction to this section Both metho ds
pro cessor must supp ort a maximum vector index of at least
call the generic function again to pro duce the external rep
resentation of the elements stored in the vector
A converter pair method
A Arguments
vector A vector
A Result
Constructs and returns a prop er list the elements of which
corresp ond to the elements stored in the instance of vector
A equal method
A Arguments
vector an instance of vector
1
vector an instance of vector
2
Programming Language EuLisp version
Annex B
normative
Programming Language EuLisp Level
B Classes and Ob jects shared slot description for slots whose values are
shared by all the instances of the class New slot descrip
tion classes can b e de ned and used here This option can
B defclass de ning form
only b e sp eci ed once for a particular slot Within a class
di erent slots can have di erent slot description classes
B Syntax
identi er expression The symb ol named by identi er
defclass class name superclass slot description
and the value of expression are passed to make of the slot
class option
description class along with other slot options The values
are evaluated in the lexical and dynamic environment of
the defclass For the language de ned slot description
B Arguments
classes no slot initargs are de ned which are not sp eci ed
by particular defclass slot options
class name A symb ol naming a binding to b e initiali sed
with the new class
The additional class option s are
superclass A list of symb ols naming bindings of
metaclass class The value of this option is the class of
classes to b e used as the sup erclasses of the new class
the new class By default this is class This option
This is di erent from defcalss at level where only one
must only b e sp eci ed once for the new class
sup erclass may b e sp eci ed
identi er expression The symb ol named by identi er
slot description A list of slot sp eci cations see b e
and the value of expression are passed to make on the class
low comprising either a slot name or a list of a slot name
of the new class This list is app ended to the end of the
followed by some slot options An additional class option
list that defclass constructs The values are evaluated
at level allows for the sp eci cation of the class of the slot
in the lexical and dynamic environment of the defclass
description
This option is used for metaclasses which need extra in
formation not provided by the standard options
class option A sequence of keys and values see b elow
An additional class options at level allows for the sp eci
cation of the metaclass of the class
B Remarks
This de ning form de nes a new class The resulting class
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
The third argument is a list of slot descriptions The remain
ing arguments are class options The syntax of defclass is
given in Table B
Table B defclass syntax level
class name identi er
superclass f class or one of its subclassesg
slot description slot name j
slot name slot option
slot name identi er
slot option slot class slot description class j
identi er expression
level slot option
class option metaclass class name j
identi er expression
level class option
The additional slot option s are
slot class class The corresp onding value is a sub
class of slot description An implementation
conforming at level provides the slot description
class local slot description for slots particu
lar to instances Extension mo dules can de ne
Programming Language EuLisp version
B Generic Functions defgeneric gf arg arg class a
class another gf class
B defgeneric de ning form
class key a class value a
class key b class value b
B Syntax
method method class another method class a
defgeneric gf name gen lambda list level init option
method class a key a method class a value a
m arg class b m arg class c
B Arguments
method method class another method class b
method class b key a method class b value a
m arg class d m arg class e
gf name As level See section
method method class another method class c
lambda list As level See section
method class c key a method class c value a
m arg class f m arg class g
init option Format as level but with additional op
tions which are de ned b elow
B Remarks
B defmethod macro
This de ning form de nes a new generic function The re
sulting generic function will b e b ound to gf name The sec
B Syntax
ond argument is the formal parameter list An error is sig
defmethod method init option gf name spec lambda list
naled condition non congruent lambda lists if any of
form
the metho ds de ned on this generic function do not have
or
lamb da lists congruent to that of the generic function This
defmethod method init option setter identi er spec
applies b oth to metho ds de ned at the same time as the
lambda list form
generic function and to any metho ds added subsequently by
or
defmethod or add method An init option is a identi er fol
defmethod method init option converter identi er
lowed by its initial value The syntax of defgeneric is an
spec lambda list form
extension of the level syntax see Table B
The additional init option s are interpreted as follows
B Remarks
The syntax of defmethod is extended to accept init options
class gf class The class of the new generic function
for the metho d class of the generic function to which the
This must b e a sub class of generic function The de
metho d is to b e attached Otherwise the b ehaviour is as
fault is generic function
that de ned in level
method class method class The class of all metho ds to
b e de ned on this generic function All metho ds of a
B generic lambda macro
generic function must b e instances of this class or of one
of its sub classes The metho d class must b e a sub class of
method and is by default method
B Syntax
generic lambda lambda list level init option
identi er expression The symb ol named by identi er
and the value of expression are passed to make on the in
stance of the new generic function and each new metho d
B Remarks
The values are evaluated in the lexical and dynamic envi
ronment of the defgeneric This option is used for classes
generic lambda creates and returns an anonymous generic
function that can b e applied immediately much like the nor which need extra information not provided by the stan
dard options
mal lambda The rst argument is a lamb da list while
the init option s are interpreted exactly as for the level
de nition of defgeneric An error is signaled condition
no applicable method if an attempt is made to apply a
B Examples
generic function which has no applicabl e metho ds for the
In the following example of the use of defgeneric a generic
classes of the arguments supplied
function named gf is de ned The di erences b etween this
function and gf see are
B Examples
a The class of the generic function is sp eci ed
In the following example an anonymous version of gf see
another gf class along with some init options re
defgeneric ab ove is de ned In all other resp ects the re
lated to the creation of an instance of that class
sulting ob ject is the same as gf
b The class of the metho ds to b e attached to the
generic lambda arg arg class a
generic function is sp eci ed another method class
along with an init option related to the creation of an in
class another gf class
stance of that class
class key a class value a
Programming Language EuLisp version
Table B defgeneric syntax level
level init option level init option j
class gf class j
method class method class j
method level method description j
gf init option
gf class a subclass of generic function
method class a subclass of method
level method description method init option spec lambda list form
gf init option identi er expression
method init option identi er expression
class key b class value b
method m arg class d m arg class e
method method class another method class a
method class a key a method class a value a
m arg class b m arg class c
method method class another method class b
method class b key a method class b value a
m arg class d m arg class e
method method class another method class c
method class c key a method class c value a
m arg class f m arg class g
B See also defgeneric
B generic labels macro
B Syntax
generic labels lambda list level init option form
B Remarks
This form is analogous to the normal labels The rst ar
gument is a binding list of the same form as that sp eci ed
for the level de nition of defgeneric The lexical environ
ment of each de ned generic function includes the others
just like labels
B Examples
In the following example two generic functions gf a and
gf b are de ned In addition the same init options
namely class and method class can b e sp eci ed
generic labels
gf a arg arg class a
method method class another method class a
method class a key a method class a value a
m arg class b m arg class c
method method class another method class b
method class b key a method class b value a
m arg class d m arg class e
method method class another method class c
method class c key a method class c value a
m arg class f m arg class g
gf b arg class b arg class c
method m arg class b m arg class c
Programming Language EuLisp version
Table B Slot Description Metaob ject Classes
B Re ection on Ob jects
object abstract class
The only re ective capability of any ob ject is the access to
class metaclass
its class that is introsp ection
metaclass metaclass
abstract class metaclass
slot description class
B class of function
B Re ection on Classes and Slot Descriptions
B Arguments
Standard classes are not rede nable and supp ort single in
object An ob ject
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
The class of the ob ject
facilities can b e provided by extensions The distinction
b etween metaclasses and non metaclasses is made explicit
by a sp ecial class named metaclass which is the class
B Remarks
of all metaclasses This is di erent from Ob jVlisp where
class of is a total function capable of taking any entity in
whether a class is a metaclass dep ends on the sup erclass list
the system and returning an ob ject representing the class of
of the class in question It is implementation de ned whether
that entity The comp osition of this function with itself is a
metaclass itself is sp ecializab le or not This implies that
function that returns the metaclass of an ob ject class of
implementations are free to restrict the instantiation tree
is a re ective op eration
excluding the sel nstantiati on lo op of metaclass to a
depth of three levels
B Examples
The minimal information asso ciated with a class metaob ject
In the following examples we explore the class hierarchy
is
starting from the single precision integer
a The name which has no semantic e ect
class of
single precision integer
b The class precedence list ordered most sp eci c rst
class of class of
b eginning with the class itself
class
class of class of class of
c The list of e ective slot descriptions
metaclass
class of class of class of class of
d The list of e ective initargs
metaclass
Standard classes supp ort lo cal slots only Shared slots can b e
provided by extensions The minimal information asso ciated
with a slot description metaob ject is
a The name which is required to p erform inheritance
computations
b The initfunction called by default to compute the
initial slot value when creating a new instance
c The reader which is a function to read the corresp ond
ing slot value of an instance
d The writer which is a function to write the corre
sp onding slot of an instance
The metaob ject classes de ned for slot descriptions at level
are shown in Table B
B slot description class
The abstract class of all slot descriptions
B local slot description class
The class of all lo cal slot descriptions
Programming Language EuLisp version
B Init options
B class initargs function
name string The name of the slot useful for debugging
only
B Arguments
reader function The function to access the slot
class A class
writer function The function to up date the slot
B Result
initfunction function The function to compute the
A list of symb ols corresp onding to the slot names sp eci ed
initial value in the absence of supplied value
when the class was de ned and any additional keywords for
slot options or class options
B class name function
B Remarks
The initargs contain the legal keywords which can b e used
B Arguments
to initiali ze instances of the class
class A class
B slot description name function
B Result
B Arguments
The symb ol which was given as the rst argument to
defstruct or defclass when the class was de ned
slot description A slot description
B Remarks
B Result
The class name has no signi cance other than for debugging
The symb ol which was used to name the slot when the class
of which the slot description is part was de ned
B class precedence list function
B Remarks
The slot description name is used to identify a slot descrip
B Arguments
tion in a class It has no e ect on bindings
class A class
B slot description initfunction function
B Result
B Arguments
A list of classes which are the sup erclasses of class in order
of increasing generality
slot description A slot description
B Remarks
B Result
The class precedence list controls the inheritance of slots and
A function
metho ds
B slot description slot reader function
B class slot descriptions function
B Arguments
B Arguments
slot description A slot description
class A class
B Result
A function
B Result
A list of slot descriptions one for each of the slots of an
instance of class
B slot description slot writer function
B Remarks
B Arguments
The slot descriptions determine the instance size numb er of
slot description A slot description
slots and the slot access
Programming Language EuLisp version
B Result initargs
A function
slot descriptions
B De ning Metaclasses c Compute new slot accessors and ensure all new and
inherited accessors to work correctly on instances of the
new class
B defmetaclass de ning form
d Make the results accessible by class readers
B Syntax
The basic call structure is laid out in Figure B
defmetaclass class name superclass slot description
class option
B Initializing Slot Descriptions
B Arguments
B initialize method
class name A symb ol naming a binding to b e initiali sed
with the new class
B Sp ecialized Arguments
superclass A symb ol naming a binding of a class to b e
slot description slot description A slot descrip
used as the sup erclass of the new class
tion
slot description A list of slot sp eci cations see b e
low
initlist list A list of initiali zati on options as fol
lows
class option A sequence of symb ols see b elow
name symbol The name of the slot
B Remarks
initfunction function A function
This de ning form de nes a new metaclass The resulting
metaclass will b e b ound to class name The second argu
ment is a sup erclass A valid class option is predicate
B Result
The initialize d slot description
B Initializing Classes
B Inheritance Proto col
B initialize method
B compatible superclasses p generic function
B Sp ecialized Arguments
B Generic Arguments
class class A class
class class Class b eing de ned
initlist list A list of initiali zati on options as fol
lows
direct superclasses list List of p otential direct su
p erclasses
name symbol Name of the class b eing initializ ed
direct superclasses list List of direct sup erclasses
B Result
direct slot descriptions list List of slot sp eci ca
True or false
tions
direct initargs list List of direct initargs
B Remarks
Checks compatibili ty b etween class and the list of direct su
p erclasses
B Result
The initialize d class
B compatible superclasses p method
B Remarks
The initializa tion of a class takes place as follows
B Sp ecialized Arguments
a Check compatibility of direct sup erclasses
class class Class b eing de ned
b Perform the logical inheritance computations of
direct superclasses list List of p otential direct su
p erclasses
class precedence list
Programming Language EuLisp version
Figure B Initialization Call Structure
COMPATIBLE SUPERCLASSES P cl direct superclasses boolean
COMPATIBLE SUPERCLASS P cl superclass boolean
COMPUTE CLASS PRECEDENCE LIST cl direct superclasses list class
COMPUTE INHERITED INITARGS cl direct superclasses list list initarg
COMPUTE INITARGS cl direct initargs inherited initargs list initarg
COMPUTE INHERITED SLOT DESCRIPTIONS cl direct superclasses list list slotd
COMPUTE SLOT DESCRIPTIONS cl direct slotds inherited slotds list slotd
either
COMPUTE DEFINED SLOT DESCRIPTION cl slotd init list slotd
COMPUTE DEFINED SLOT DESCRIPTION CLASS cl slotd init list slotd class
or
COMPUTE SPECIALIZED SLOT DESCRIPTION cl inherited slotds slotd init list slotd
COMPUTE SPECIALIZED SLOT DESCRIPTION CLASS cl inherited slotds slotd init list slotd class
COMPUTE AND ENSURE SLOT ACCESSORS cl effective slotds inherited slotds list slotd
COMPUTE SLOT READER cl slotd effective slotds function
COMPUTE SLOT WRITER cl slotd effective slotds function
ENSURE SLOT READER cl slotd effective slotds reader function
COMPUTE PRIMITIVE READER USING SLOT DESCRIPTION slotd cl effective slotds function
COMPUTE PRIMITIVE READER USING CLASS cl slotd effective slotds function
ENSURE SLOT WRITER cl slotd writer function
COMPUTE PRIMITIVE WRITER USING SLOT DESCRIPTION slotd cl effective slotds function
COMPUTE PRIMITIVE WRITER USING CLASS cl slotd effective slotds function
B Result B Remarks
True or false This metho d returns true if the class of the rst argument
is a sub class of the class of the second argument false oth
erwise
B Remarks
The default metho d calls compatible superclass p on class
and the rst element of the direct superclasses single inher
B compatible superclass p method
itance assumption
B Sp ecialized Arguments
B compatible superclass p generic function
subclass class Class b eing de ned
superclass abstract class Potential direct sup er
B Generic Arguments
class
subclass class Class b eing de ned
B Result
superclass class Potential direct sup erclass
True
B Result
B Remarks
True or false
This metho d always returns true
B Remarks
Checks compatibili ty b etween a sub class b eing de ned rst
B compatible superclass p method
argument and a p otential sup erclass second argument
B Sp ecialized Arguments
B compatible superclass p method
subclass abstract class Class b eing de ned
superclass class Potential direct sup erclass
B Sp ecialized Arguments
subclass class Class b eing de ned
B Result
False
superclass class Potential direct sup erclass
B Remarks
B Result
True or false This metho d always returns false
Programming Language EuLisp version
B compute class precedence list generic function B compute slot descriptions method
B Generic Arguments B Sp ecialized Arguments
class class Class b eing de ned
class class Class b eing de ned
direct superclasses list List of direct sup erclasses
slot specs list List of direct slot sp eci cations
inherited slot description lists list A list of lists
B Result
in fact one list of inherited slot descriptions
List of classes
B Result
B Remarks
List of e ective slot descriptions
Computes and returns a list of classes which represents the
linearized inheritance hierarchy of class and the given list
B Remarks
of direct sup erclasses b eginning with class and ending with
object
The default metho d computes two sublists
a Sp ecialized slot descriptions by calling
compute specialized slot description on class each
B compute class precedence list method
inherited slot description wrapp ed by a list and the corre
sp onding same name slot speci cation if there exits one
B Sp ecialized Arguments
or otherwise
class class Class b eing de ned
b New slot descriptions by
calling compute defined slot description on class and
direct superclasses list List of direct sup erclasses
each slot speci cation which has no corresp onding same
name inherited slot description
B Result
The metho d returns the concatenation of these two lists as
its result The order of elements in the list is signi cant
List of classes
All sp ecialized slot descriptions have the same p osition as
in the e ective slot descriptions list of the direct sup erclass
B Remarks
due to the single inheritance The slot accessors computed
later may rely on this assumption minimizing the numb er of
This metho d can b e considered to return a cons of its rst
metho ds to one for all sub classes and minimizing the access
argument and the class precedence list of the rst element
time to an indexed reference
of list single inheritance assumption
B
B compute slot descriptions generic function
See also compute specialized slot description
compute defined slot description
compute and ensure slot accessors
B Generic Arguments
class class Class b eing de ned
B compute initargs generic function
direct slot descriptions list A list of direct slot de
scriptions
B Generic Arguments
inherited slot descriptions list A list of lists of in
class class Class b eing de ned
herited slot descriptions
initargs list List of direct initargs
B Result
inherited initarg lists list A list of lists of inher
List of e ective slot descriptions
ited initargs
B Remarks
B Result
Computes and returns the list of e ective slot descriptions
List of symb ols
of class
B Remarks
B
See also compute inherited slot descriptions Computes and returns all legal initargs for class
Programming Language EuLisp version
B See also compute inherited initargs
B compute inherited initargs generic function
B compute initargs method
B Generic Arguments
class class Class b eing de ned
B Sp ecialized Arguments
direct superclasses list List of direct sup erclasses
class class Class b eing de ned
initargs list List of direct initargs
B Result
inherited initarg lists list A list of lists of inher
List of lists of symb ols
ited initargs
B Remarks
B Result
Computes and returns a list of initarg lists Its result is used
List of symb ols
by compute initargs as an argument value
B Remarks
B See also compute initargs
This metho d app ends the second argument with the rst ele
ment of the third argument single inheritance assumption
removes duplicates and returns the result
B compute inherited initargs method
B Sp ecialized Arguments
B compute inherited slot descriptions
generic function
class class Class b eing de ned
direct superclasses list List of direct sup erclasses
B Generic Arguments
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 e ective slot description lists
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
B Sp ecialized Arguments
slot spec list Canonicalized slot sp eci cation
class class Class b eing de ned
B Result
direct superclasses list List of direct sup erclasses
Slot description
B Result
B Remarks
List of lists of inherited slot descriptions
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
The result of the default metho d is a list of one element a list
of e ective slot descriptions of the rst element of the second
argument single inheritance assumption Its result is used B
by compute slot descriptions as an argument value See also compute defined slot description class
Programming Language EuLisp version
B compute defined slot description method B compute specialized slot description
generic function
B Sp ecialized Arguments
B Generic Arguments
class class Class b eing de ned
class class Class b eing de ned
slot spec list Canonicalized slot sp eci cation
inherited slot descriptions list List of inherited
slot descriptions
B Result
slot spec list Canonicalized slot sp eci cation or
Slot description
B Remarks
B Result
Computes and returns a new ef
Slot description
fective slot description Its class 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
class class Class b eing de ned
B compute specialized slot description 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
slot spec list Canonicalized slot sp eci cation or
Determines and returns the slot description class corresp ond
ing to class and list
B Result
B See also compute defined slot description
Slot description
B compute defined slot description class
B Remarks
method
Computes and returns a new ef
fective slot description Its class is determined by calling
compute specialized slot description class
B Sp ecialized Arguments
class class Class b eing de ned
B
See also compute specialized slot description class
slot spec list Canonicalized slot sp eci cation
B compute specialized slot description class
B Result
generic function
The class slot description
B Generic Arguments
B Remarks
class class Class b eing de ned This metho d just returns the class slot description
Programming Language EuLisp version
inherited slot descriptions list List of inherited A new metho d might b e necessary if the sub classes have a
slot descriptions di erent instance allo cation or if the slot p ositions cannot
b e kept the same as in the sup erclass in multiple inheri
slot spec list Canonicalized slot sp eci cation or tance extensions This can b e done during the initializa tion
computations
B Result
B compute and ensure slot accessors
Slot description class
generic function
B Remarks
B Generic Arguments
Determines and returns the slot description class corresp ond
class class Class b eing de ned
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
slot descriptions list List of e ective slot descrip
in slot spec
tions
inherited slot descriptions list List of inherited
B
slot descriptions
See also compute specialized slot description
B Result
B compute specialized slot description class
List of e ective slot descriptions
method
B Remarks
B Sp ecialized Arguments
Computes new accessors or ensures that inherited accessors
class class Class b eing de ned
work correctly for each e ective slot description
inherited slot descriptions list List of inherited
slot descriptions
B compute and ensure slot accessors method
slot spec list Canonicalized slot sp eci cation or
B Sp ecialized Arguments
class class Class b eing de ned
B Result
The class slot description
slot descriptions list List of e ective slot descrip
tions
B Remarks
inherited slot descriptions list List of inherited
slot descriptions
This metho d just returns the class slot description
B Result
B Slot Access Proto col
List of e ective slot descriptions
The slot access proto col is de ned via accessors readers and
writers only There is no primitive like CLOS s slot value
B Remarks
The accessors are generic for standard classes since they
have to work on sub classes and should do the applicabil i ty
The default metho d checks if it is a new slot description not
check anyway The key idea is that the discriminati on on
an inherited one If yes
slot descriptions and classes is p erformed once at class de
nition time rather than again and again at slot access time
a calls compute slot reader to compute a new slot
reader and stores the result
Each slot description has exactly one reader and one writer
as anonymous ob jects If a reader writer slot option is sp eci
b calls compute slot writer to compute a new slot
ed in a class de nition the anonymous reader writer of that
writer and stores the result
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
If not assumes that the inherited values remain valid Last
ob ject is b ound to all the identi ers If the accessor slot
it ensures the reader and writer to work correctly calling
option is sp eci ed the anonymous writer will b e installed as
ensure slot reader and ensure slot writer
the setter of the reader Sp ecialized slot descriptions refer
to the same ob jects as those in the sup erclasses single in
heritance makes that p ossible Since the readers writers are
B compute slot reader generic function
generic it is p ossible for a sub class at the meta level to add
new metho ds for inherited slot description s in order to make
B Generic Arguments the readers writers applicabl e on instances of the sub class
Programming Language EuLisp version
class class Class
B compute slot writer method
slot description slot description Slot
description
B Sp ecialized Arguments
slot descriptions list List of e ective slot descrip
tions 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
B Result
stances of class returning the slot value corresp onding to
Generic function
slot description The third argument can b e used in order to
compute the logical slot p osition
B Remarks
The default metho d returns a new generic function of two
B compute slot reader method
arguments without any metho ds Its domain is the pro duct
of class and object
B Sp ecialized Arguments
B ensure slot reader generic function
class class Class
slot description slot description Slot
B Generic Arguments
description
class class Class
slot descriptions list List of e ective slot descrip
tions
slot description slot description Slot
description
B Result
slot descriptions list List of e ective slot descrip
Generic function
tions
reader function The slot reader
B Remarks
The default metho d returns a new generic function of one
argument without any metho ds Its domain is class
B Result
Function
B compute slot writer generic function
B Remarks
Ensures function works correctly on instances of class
B Generic Arguments
class class Class
B ensure slot reader method
slot description slot description Slot
description
B Sp ecialized Arguments
slot descriptions list List of e ective slot descrip
class class Class
tions
slot description slot description Slot
description
B Result
Function
slot descriptions list List of e ective slot descrip
tions
B Remarks
reader generic function The slot reader
Computes and returns a new slot writer applicable to in
stances of class and any value to b e stored as the new slot
B Result
value corresp onding to slot description The third argument
can b e used in order to compute the logical slot p osition Generic function
Programming Language EuLisp version
B Remarks compute primitive writer using slot description
is called by the metho d function to compute the primitive
The default metho d checks if there is a metho d in the
writer
generic function If not it creates and adds a new one The
new metho d has
domain class
B compute primitive reader using slot description
generic function
method fufunction nction lambda object class
primitive reader object
B Generic Arguments
compute primitive reader using slot description
is called by the metho d function to compute the primitive
slot description slot description Slot
reader
description
class class Class
B ensure slot writer generic function
slot descriptions list List of e ective slot descrip
tions
B Generic Arguments
class class Class
B Result
Function
slot description slot description Slot
description
B Remarks
slot descriptions list List of e ective slot descrip
tions
Computes and returns a function which returns a slot value
when applied on an instance of class
writer function The slot writer
B compute primitive reader using slot description
B Result
method
Function
B Sp ecialized Arguments
B Remarks
Ensures function to work correctly on instances of class
slot description slot description Slot
description
B ensure slot writer method
class class Class
slot descriptions list List of e ective slot descrip
B Sp ecialized Arguments
tions
class class Class
B Result
slot description slot description Slot
description
Function
slot descriptions list List of e ective slot descrip
tions
B Remarks
Calls compute primitive reader using class This is the
writer generic function The slot writer
default metho d
B Result
B compute primitive reader using class
Generic function
generic function
B Remarks
B Generic Arguments
The default metho d checks if there is a metho d in the
generic function If not creates and adds a new one The
class class Class
new metho d has
slot description slot description Slot
domain class object
description
method fufunction nction lambda obj class
slot descriptions list List of e ective slot descrip
new value object
tions
primitive writer obj new value
Programming Language EuLisp version
B Result B Result
Function
Function
B Remarks
B Remarks
Computes and returns a function which returns the slot value
Calls compute primitive writer using class This is the
when applied on an instance of class
default metho d
B compute primitive writer using class
B compute primitive reader using class method
generic function
B Sp ecialized Arguments
B Generic Arguments
class class Class
class class Class
slot description slot description Slot
description slot description slot description Slot
description
slot descriptions list List of e ective slot descrip
tions
slot descriptions list List of e ective slot descrip
tions
B Result
B Result
Function
Function
B Remarks
B Remarks
The default metho d returns a function of one argument
Computes and returns a function which stores the new slot
value when applied on an instance of class and new value
B compute primitive writer using slot description
generic function
B compute primitive reader using class method
B Generic Arguments
B Sp ecialized Arguments
slot description slot description Slot
description
class class Class
class class Class
slot description slot description Slot
description
slot descriptions list List of e ective slot descrip
tions
slot descriptions list List of e ective slot descrip
tions
B Result
Function
B Result
Function
B Remarks
Computes and returns a function which stores a new slot
B Remarks
value when applied on an instance of class and a new value
The default metho d returns a function of two arguments
B compute primitive writer using slot description
B Predicates and Constructors
method
B compute predicate generic function
B Sp ecialized Arguments
B Generic Arguments
slot description slot description Slot
description
class class Class
class class Class
B Result
slot descriptions list List of e ective slot descrip
Function
tions
Programming Language EuLisp version
B Remarks class class A class
Computes and returns a predicate function of one argument
initlist list A list of initiali zati on arguments
B compute predicate method
B Result
An instance of the rst argument
B Sp ecialized Arguments
class class Class
B Remarks
Creates an instance of the rst argument Users may de ne
new metho ds for new metaclasses
B Result
Function
B allocate method
B Remarks
Computes and returns a predicate function of one argument
B Sp ecialized Arguments
which returns true when applied on direct or indirect in
stances of class and false otherwise
class class A class
initlist list A list of initiali zati on arguments
B compute constructor generic function
B Result
B Generic Arguments
An instance of the rst argument
class class Class
B Remarks
parameters list Argument list of the function b e
ing created
The default metho d creates a new uninitial i zed instance of
the rst argument The initlist is not used by this allocate
metho d
B Result
Function
B Low Level Allo cation Primitives
B Remarks
This mo dule provides primitives which are necessary to im
Computes and returns a constructor function
plement new allo cation metho ds p ortably However they
should b e de ned in such a way that ob jects cannot b e de
stroyed unintentional ly In consequence it is an error to use
primitive class of primitive ref and their setters on
B compute constructor method
ob jects not created by primitive allocate
B Sp ecialized Arguments
B primitive allocate function
class class Class
parameters list Argument list of the function b e
B Arguments
ing created
class A class
B Result
size An integer
Function
B Result
B Remarks
An instance of the rst argument
Computes and returns a constructor function which returns
a new instance of class when applied
B Remarks
B Instance Allo cation
This function returns a new instance of the rst argument
which has a vector like structure of length size The com
p onents of the new instance can b e accessed by means
B allocate generic function
of primitive ref and setter primitive ref It is in
tended to b e used in new allocate metho ds de ned for new
B Generic Arguments metaclasses
Programming Language EuLisp version
B primitive class of function B setter primitive ref function
B Arguments
B Arguments
object An ob ject created by primitive allocate
object An ob ject created by primitive allocate
index The index of a comp onent
B Result
value The new value which can b e any ob ject
A class
B Result
The new value
B Remarks
This function returns the class of an ob ject It is similar to
class of which has a de ned b ehaviour on any ob ject It is
B Remarks
an error to use primitive class of on ob jects which were
Stores and returns the new value as the ob jects comp onent
not created by primitive allocate
corresp onding to the supplied index It is an error if the
index is out of range This function is intended to b e used
when de ning new kinds of accessors for new metaclasses
B setter primitive class of setter
B Arguments
object An ob ject created by primitive allocate
class A class
B Result
The class
B Remarks
This function supp orts p ortable implementations of
a dynamic classi catio n like change class in CLOS
b automatic instance up dating of rede ned classes
B primitive ref function
B Arguments
object An ob ject created by primitive allocate
index The index of a comp onent
B Result
An ob ject
B Remarks
Returns the value of the ob jects comp onent corresp onding
to the supplied index It is an error if the index is out of
range This function is intended to b e used when de ning
new kinds of accessors for new metaclasses
Programming Language EuLisp version
Table B Metaob ject Classes
B generic function name function
Table B Generic Function Metaob ject Classes
object abstract class
B Arguments
class metaclass
metaclass metaclass
generic function A generic function
abstract class metaclass
function class metaclass
generic function function class
B Result
method class
A symb ol
B Remarks
B Re ection on Generic Functions and
The name has only debugging purp oses
Metho ds
The generic dispatch is class based i e metho ds are class
B See also class name
sp eci c Instance sp eci c metho ds can b e provided even
p ortably in an extension mo dule by de ning a new generic
function class We think it is confusing to have generic func
B generic function domain function
tions with b oth class sp eci c and instance sp eci c meth
o ds Combining di erent discriminati on strategies in a single
generic function is rather a shortcoming than an advantage
B Arguments
The argument precedence order is always left to right
generic function A generic function
The minimal information asso ciated with a generic function
metaob ject is
B Result
a The name which has no semantic e ect
List of classes
b The domain restricting the domain of each added
metho d to a sub domain
B Remarks
c The range restricting the range of each added metho d
Returns the domain of a generic function All metho ds at
to a subrange
tached to a generic function have sub domains of it
d The metho d class restricting each added metho d to
b e an instance direct or indirect of that class
B generic function range function
e The list of all added metho ds
B Arguments
f The metho d lo ok up function to collect and sort the
applicabl e metho ds
generic function A generic function
g The discriminatin g function to p erform the generic
dispatch
B Result
A class
The minimal information asso ciated with a metho d metaob
ject is
B Remarks
a The domain which is a list of classes
Returns the range of a generic function Each metho d at
tached to a generic function must have a subrange of it
b The range which is a class
c The function comprising the co de of the metho d
B generic function method class function
d The generic function if the metho d has b een added
to one at the most
B Arguments
generic function A generic function
The metaob ject classes for generic functions de ned at level
are shown in Table B
B Result
B Introsp ection
A class
Programming Language EuLisp version
B Remarks B Result
Returns the metho d class of a generic function Each metho d
List of classes
attached to a generic function must b e an instance of that
class When a metho d is de ned using defmethod it will b e
an instance of that class by default
B Remarks
Returns the domain of a metho d
B generic function methods function
B method range function
B Arguments
B Arguments
generic function A generic function
method A metho d
B Result
A list of metho ds
B Result
A class
B Remarks
Returns a list of metho ds attached to the generic function
B Remarks
Returns the range 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 A metho d
B Result
A function
B Result
B Remarks
A function
Returns a function applicabl e on same arguments as the
generic function which returns a sorted list of applicabl e
B Remarks
metho ds when applied
Returns the function which is called when a metho d is called
The metho d itself can not b e applied or called as a function
B generic function discriminating function
function
B method generic function function
B Arguments
B Arguments
generic function A generic function
method method A metho d
B Result
A function
B Result
A generic function or false
B Remarks
Returns a function applicabl e on same arguments as the
generic function which is called everytime when the generic
B Remarks
function is called It p erforms the generic dispatch and calls
Returns the generic function to which the metho d is at
the applicable metho ds
tached false otherwise
B method domain function
B Sp ecial forms or macros
The followin macros hide the implementation details of call
B Arguments
ing metho ds arranging the next metho ds so that they are
accessible by call next method etc
method A metho d
Programming Language EuLisp version
generic function generic function A generic func
tion
B method function lambda macro
B call method macro
B Result
The initiali zed metho d
B apply method macro
B Remarks
B Initializing Generic Functions and Meth
Initializes and returns the method There is nothing sp ecial
o ds
to sp ecify for this metho d
B initialize method
B Metho d Lo okup and Generic Dispatch
B Sp ecialized Arguments
B compute method lookup function
generic function
generic function generic function A generic
function
B Generic Arguments
initlist list A list of initiali zati on options as fol
lows
generic function generic function A generic
function
name symbol The name of the generic function
domain list A list of classes which span the do
domain list List of argument classes
main
range class The class of the result
B Result
method class class Class of attached metho d
A function
methods list List of metho ds to b e attached
B Remarks
B Result
Computes and returns a function which is called at least ones
The initializ ed generic function
for a particular domain in order to select and sort the appli
cable metho ds by the system provided dispatch mechanism
Users may de ne new metho ds for it in order to implement
B Remarks
di erent metho d lo okup strategies Althought there is just
Initializes and returns the generic function It calls
one lo okup strategie provided by the system each generic
compute method lookup function
function may have its own more e cient lo okup function
compute discriminating function and stores their results
as well as the direct information passed as arguments
B compute method lookup function method
The basic call structure is
COMPUTE METHOD LOOKUP FUNCTION
B Sp ecialized Arguments
generic function domain function
COMPUTE DISCRIMINATING FUNCTION
generic function generic function A generic
generic function domain lookup fn methods function
function
domain list A list of classes which span the do
B initialize method
main
B Sp ecialized Arguments
B Result
method method A metho d
A function
initlist list A list of initiali zati on options as fol
lows
B Remarks
domain list List of argument classes Computes and returns a function which is called at least ones
for a particular domain in order to select and sort the appli
range class The class of the result cable metho ds by the system provided dispatch mechanism
It is not sp eci ed whether or not each generic function gets
function function A function its own lo okup function
Programming Language EuLisp version
remove a metho d with the same domain as the metho d b e
ing added Instead remove method must b e used explicitly
B compute discriminating function
b efore adding the new one
generic function
B Generic Arguments
B add method generic function
generic function generic function A generic
B Generic Arguments
function
generic function generic function A generic
domain list A list of classes which span the do
function
main
method method A metho d to b e attached
lookup function function The metho d lo okup
function
B Result
methods list A list of metho ds attached to the
The generic function
generic function
B Remarks
B Result
Adds a metho d to a generic function User may de ne new
A function
metho ds to it for new generic function and metho d classes
B Remarks
B add method method
Computes and returns a function which is called whenever
the generic function is called It is the controller of the
generic dispatch Users may de ne new metho ds for new
B Sp ecialized Arguments
generic function classes in order to implement other dispatch
strategies e g eql discrimi nati on as in CLOS
generic function generic function A generic
function
method method A metho d to b e attached
B compute discriminating function method
B Result
B Sp ecialized Arguments
The generic function
generic function generic function A generic
function
B Remarks
Checks if the domain the range as well as the class of the
domain list A list of classes which span the do
metho d are more sp ecial than those of the generic function
main
If not signals an error Checks if there is a metho d with the
same domain attached to the generic function already If
lookup function function The metho d lo okup
yes signals an error If no error o ccures adds the metho d to
function
the generic function Dep ending on particular optimizations
of the generic dispatch adding a metho d may cause some
methods list A list of metho ds attached to the
up dating computations
generic function
B remove method generic function
B Result
A function
B Generic Arguments
B Remarks
generic function generic function A generic
Computes and returns a function which is called whenever
function
the generic function is called It is unsp eci ed which opti
mizations are provided by this function
method method A metho d to b e removed
B Result
B Extending Generic Functions by New
Metho ds
The generic function
These op erations provide means to add and remove meth
B Remarks
o ds dynamicall y to from generic functions They are in
Removes a metho d from a generic function User may de ne tended to supp ort p ortable programming environment im
new metho ds for new generic function and metho d classes plementations In contrast to CLOS add method do es not
Programming Language EuLisp version
B Dynamic Binding
B remove method method
B dynamic special form
B Sp ecialized Arguments
B Syntax
generic function generic function A generic
dynamic identi er
function
method method A metho d to b e removed
B Arguments
identi er A symb ol naming a dynamic binding
B Result
The generic function
B Result
The value of closest dynamic binding of symbol named by
B Remarks
identi er is returned If no such binding exists an error is
If the metho d is attached to the generic function it will b e
signaled condition unbound dynamic variable
removed as well as the backp ointer from the metho d to the
generic function Dep ending on particular optimizations of
the generic dispatch removing a metho d may cause some
B dynamic setq special form
up dating computations
B Syntax
dynamic setq identi er form
B Arguments
identi er A symb ol naming a dynamic binding to b e
up dated
form An expression whose value will b e stored in the
dynamic binding of identi er
B Result
The value of form
B Remarks
The form is evaluated and the result is stored in the closest
dynamic binding of symbol named by identi er An error
is signaled condition unbound dynamic variable if sym
bol is not dynamicall y apparent and has no dynamic global
value
B unbound dynamic variable execution condition
B Init 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
B dynamic let special form
B Syntax
dynamic let binding form
Programming Language EuLisp version
B Arguments when antecedent form
binding A list of binding sp eci ciers
B Remarks
body A sequence of forms
The when op erator evaluates antecedent and if the result is
not the forms are evaluated from left to right It is
equivalent to if with a null alternative If the evaluation of
B Result
antecedent is not the result of the when form is that of
The sequence of forms is evaluated in order returning the
the evaluation of the last form otherwise the result is
value of the last one as the result of the dynamic let form
The rewrite rule for when is
B Remarks
when Is an error
A binding sp eci er is either an identi er or a two element
when antecedent
list of an identi er and an initiali zi ng form All the initial
when form form if form progn form
1 2 1 2
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 environment to
B unless macro
hold the results These bindings have dynamic scop e and
dynamic extent Each form in body is evaluated in order in
the environment extended by the ab ove bindings The result
B Syntax
of evaluating the last form in body is returned as the result
unless antecedent form
of dynamic let
B Remarks
B defvar de ning form
The unless op erator evaluates the rst form and if the result
is the remaining forms are evaluated from left to right It
B Syntax
is equivalent to if with a null consequence If the evaluation
of the rst form is the result of the unless form is the
defvar name expression
result of the evaluation of the last form otherwise the result
is The rewrite rule for unless is
B Arguments
identi er A symb ol naming a top dynamic binding con
unless Is an error
taining the value of form
unless antecedent
unless form form if form progn form
1 2 1 2
form The form whose value will b e stored in the top
dynamic binding of identi er
B Exit Extensions
B Remarks
B block macro
The value of form is stored as the top dynamic value
of the symb ol named by identi er The binding created
by defvar is mutable An error is signaled condition
B Syntax
dynamic multiply defined on evaluating this form more
block identi er form
than once for the same identi er
B Remarks
B dynamic multiply defined execution condition
The blo ck expression is used to establish a statically scop ed
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
B Init options
invoked anywhere within the blo ck by using return from
The forms are evaluated in sequence and the value of the
symbol symbol A symb ol naming the dynamic variable
last one is returned as the value of the blo ck form See also
which has already b een de ned
let cc The rewrite rules for block are
B Remarks
block Is an error
Signalled by defvar if the named dynamic variable already
block identi er
exists
block identi er form let cc identi er form
Exiting from a block by whatever means causes the restora
B Conditional Extensions
tion of the lexical environment and dynamic environment
that existed b efore block entry The ab ove rewrite for block
B when macro
do es not prevent the block b eing exited from anywhere in its
dynamic extent since the block exit function is a rst class
B Syntax item and can b e passed as an argument like other values
Programming Language EuLisp version
B See also return from B Remarks
In throw the tag names the continuation of the catch from
which to return throw is the invo cation of the continuation
B return from macro
of the catch named tag The form is evaluated and the value
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
B Syntax
binding of the symb ol which is where the continuation is
return from identi er form
b ound The rewrite rules for throw are
throw Is an error
B Remarks
throw tag dynamic tag
In return from the identi er names the continuation of the
throw tag form dynamic tag form
lexical block from which to return return from is the
invo cation of the continuation of the blo ck named by identi
B See also catch
er The form is evaluated and the value is returned as the
value of the blo ck named by identi er The rewrite rules for
return from are
B Summary of Level Expressions and Def
return from Is an error
initions
return from identi er identi er
return from identi er form identi er form
The syntax of all level expressions and de nitions is given
in Table B Any pro ductions unde ned here app ear else
where in the de nition sp eci cally the syntax of most ex
B See also block
pressions and de nitions is completed in the section de ning
level
B catch macro
B Syntax
catch tag form
B Remarks
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
to create a dynamically scop ed binding of tag to the contin
uation of the catch form The continuation can b e invoked
anywhere within the dynamic extent of the catch form by
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
catch Is an error
catch tag progn tag
catch tag form let cc tmp
dynamic let tag tmp
form
Exiting from a catch by whatever means causes the restora
tion of the lexical environment and dynamic environment
that existed b efore the catch was entered The ab ove rewrite
for catch causes the variable tmp to b e shadowed This is
an artifact of the ab ove presentation only and a conforming
pro cessor must not shadow any variables that could o ccur in
the b o dy of catch in this way
B See also throw
B throw macro
B Syntax
throw tag form
Programming Language EuLisp version
Table B Expressions and De nitions level
module expression export spec j level expression j level expression j de nition j progn expression
de nition level de nition j level de nition
fdefmoduleg
level de nition defclass j defcondition j defgeneric j defvar j
level de nition
defclass defclass class name superclass slot description class option
class name identi er
superclass f class or one of its subclassesg
slot description slot name j
slot name slot option
slot name identi er
slot option slot class slot description class j
identi er expression
level slot option
class option metaclass class name j
identi er expression
level class option
defgeneric defgeneric gf name gen lambda list level init option
level init option level init option j
class gf class j
method class method class j
method level method description j
gf init option
gf class a subclass of generic function
method class a subclass of method
level method description method init option spec lambda list form
gf init option identi er expression
method init option identi er expression
defvar defvar name expression
level expression dynamic let j dyn ref j dyn assign j level expression
dyn ref dynamic identi er
dyn assign dynamic setq identi er form
dynamic let dynamic let binding form
Programming Language EuLisp version
References Padget et al Padget J A et al Desiderata for the
Standardisation of Lisp Pro ceedings of ACM
Conference on Lisp and Functional Programming
Alb erga et al Alb erga C N Bosman Clark C
pp published by ACM Press New York
Mikelsons M Van Deusen M Padget J A
Experience with an Uncommon LISP Pro ceedings
Padget Padget J A A Simple Light weight Pro
of ACM Symp osium on LISP and Functional
cess Mechanism in Lisp in preparation
Programming ACM New York also available
as IBM Research Rep ort RC
Pitman Pitman K M An Error System for Com
Bobrow et al Bobrow D G DiMichiel L G
mon Lisp ISO WG pap er N
Gabriel R P Keene S E Kiczales G Mo on D A
Common Lisp Object System Speci cation SIG
Rees et al Rees J A The T Manual YALEU
PLAN Notices Vol Septemb er
Technical Rep ort
Chailloux et al Chailloux J Devin M Hul
Slade Slade S The T Programming Language a
lot J M LELISP A Portable and E cient Lisp
Dialect of Lisp Prentice Hall
System Pro ceedings of ACM Symp osium on
Lisp and Functional Programming Austin Texas
Shalit Shalit A Dylan an object oriented dy
pp published by ACM Press New York
namic language Apple Computer Inc
Chailloux et al Chailloux J Devin M Dup ont
Steele Steele G L Jr Common Lisp the Lan
F Hullot J M Serp ette B Vuillemin J le lisp
guage Digital Press and Common Lisp the
de l INRIA Version Manuel de r ef erence IN
Language second edition Digital Press
RIA Ro cquencourt May
Stoyan et al Stoyan H et al Towards a Lisp
Clinger Rees Clinger W Rees J A eds
Standard published in the Pro ceedings of the
3
The Revised Report on Scheme SIGPLAN Notices
Europ ean Conference on Arti cial Intelligence
Vol No
Teitelman Teitelman W The Interlisp Reference
Cointe Cointe P Mateclasses are First Class the
Manual Xerox Palo Alto Research Center
ObjVlisp model Pro ceedings of OOPSLA pub
lished as SIGPLAN Notices Vol No pp
Fitch Norman Fitch J P Norman A C Im
plementing Lisp in a High Level Language Software
Practice and Exp erience Vol pp
Friedman Haynes Friedman D Haynes C
Constraining Control Pro ceedings of th Annual
ACM Symp osium on Principles of Programming
Languages pp published by ACM Press
New York
Hudak Wadler et al Hudak P Wadler P
eds Report on the Functional Programming Lan
guage Haskel l Yale University Department of Com
puter Science Research Rep ort YALEU DCS RR
Decemb er
Landin Landin P J The Next Programming
Languages Communications of the ACM Vol No
pp
Lang Pearlmutter Lang K J Pearlmutter
B A Oaklisp An Object Oriented Dialect of
Scheme Lisp and Symb olic Computation Vol
No June pp published by Kluwer
Academic Publishers Boston
MacQueen MacQueen D et al Modules for
Standard ML Pro ceedings of ACM Symp o
sium on Lisp and Functional Programming Austin
Texas pp published by ACM Press New
York
Milner et al Milner R et al Standard ML Lab
oratory for the Foundations of Computer Science
University of Edinburgh Technical Rep ort
Programming Language EuLisp version
Function Index
number primitive allocate level
primitive class of level
number
primitive ref level
number
prin stream
number
read stream
number
scan formatted io
number
semaphorep semaphore
number
setter level
number
setter car pair
apply level
setter cdr pair
atom pair
setter converter convert
binary stream p stream
setter primitive class of level
car pair
setter primitive ref level
cdr pair
setter string ref string
cerror condition
setter table ref table
characterp character
setter vector ref vector
character stream p stream
signal condition
class initargs level
single precision integer p spint
class name level
slot description initfunction level
class of level
slot description name level
class precedence list level
slot description slot reader level
class slot descriptions level
slot description slot writer level
close semaphore semaphore
string append string
condition message condition
string lt string
conditionp condition
stringp string
cons pair
string ref string
consp pair
string slice string
convert convert
symbol exists p symbol
converter convert
symbol name symbol
copy alist pair
symbolp symbol
copy list pair
table delete table
copy tree pair
tablep table
current thread thread
table ref table
double float p double
threadp thread
eq compare
thread reschedule thread
eql compare
thread start thread
error condition
thread value thread
file streamp stream
vectorp vector
floatp number
vector ref vector
format formatted io
write stream
generic function discriminating function level
generic function domain level
generic function method class level
generic function method lookup function level
generic function methods level
generic function name level
generic function range level
gensym symbol
input stream p stream
integerp number
io stream p stream
list pair
make level
make initialized vector vector
max number
method domain level
method function level
method generic function level
method range level
min number
null null
numberp number
open semaphore semaphore
output stream p stream
Programming Language EuLisp version
Macro Index
and level
apply method level
block level
call method level
catch level
cond level
defmethod level
defmethod level
generic labels level
generic lambda level
let level
let level
method function lambda level
or level
quasiquote level
return from level
throw level
unless level
when level
Programming Language EuLisp version
Generic Function Index
compare generic read stream
generic write level
abs number
generic write stream
acos elementary functions
initialize level
acosh elementary functions
lcm number
add method level
log elementary functions
allocate level
log elementary functions
asin elementary functions
log elementary functions
asinh elementary functions
map character
atan elementary functions
member character
atan elementary functions
modulo spint
atanh elementary functions
negate number
binary difference number
negativep number
binary divide number
oddp spint
binary gcd number
open stream
binary lcm number
open p stream
binary lt number
peek unit stream
binary plus number
positivep number
binary times number
quotient spint
catenate character
read unit stream
ceiling double
reduce character
close stream
reduce character
compatible superclasses p level
remainder spint
compatible superclass p level
remove method level
compute and ensure slot accessors level
round double
compute class precedence list level
signum number
compute constructor level
sin elementary functions
compute defined slot description level
sinh elementary functions
compute defined slot description class level
size character
sqrt elementary functions
compute discriminating function level
tan elementary functions
compute inherited initargs level
tanh elementary functions
compute inherited slot descriptions level
truncate double
compute initargs level
wait level
compute method lookup function level
write unit stream
compute predicate level
zerop number
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
compute slot descriptions level
compute slot reader level
compute slot writer level
compute specialized slot description level
compute specialized slot description class
level
copy copy
cos elementary functions
cosh elementary functions
do character
empty p character
ensure slot reader level
ensure slot writer level
equal compare
evenp spint
exp elementary functions
expt elementary functions
fill character
filter character
floor double
flush stream
gcd number
generic prin level
generic prin stream
Programming Language EuLisp version
Metho d Index
add method level generic prin spint
generic prin string
allocate level
generic prin symbol
ceiling double
generic prin table
close stream
generic prin thread
compatible superclasses p level
generic prin vector
compatible superclass p level
generic read stream
compatible superclass p level
generic write character
compatible superclass p level
generic write character
compute and ensure slot accessors level
generic write double
compute class precedence list level
generic write null
compute constructor level
generic write pair
compute defined slot description level
generic write semaphore
compute defined slot description class level
generic write spint
generic write string
compute discriminating function level
generic write symbol
compute inherited initargs level
generic write symbol
compute inherited slot descriptions level
generic write table
compute initargs level
generic write thread
compute method lookup function level
generic write vector
compute predicate level
initialize level
compute primitive reader using class level
initialize level
compute primitive reader using class level
initialize level
compute primitive reader using slot description
initialize level
level
initialize level
compute primitive writer using slot description
initialize instance condition
level
length null
compute slot descriptions level
length pair
compute slot reader level
length string
compute slot writer level
length vector
compute specialized slot description level
modulo spint
compute specialized slot description class
oddp spint
level
open stream
converter character spint
open p stream
converter double float spint
peek unit stream
converter integer character
quotient spint
converter pair string
read unit stream
converter pair vector
remainder spint
converter single precision integer double
remove method level
converter string double
round double
converter string pair
sqrt elementary functions
converter string pair
sqrt elementary functions
converter string spint
truncate double
copy character
wait stream
copy copy
wait thread
copy double
write unit stream
copy pair
write unit stream
copy spint
copy string
copy vector
ensure slot reader level
ensure slot writer level
equal character
equal compare
equal number
equal pair
equal string
equal vector
evenp spint
floor double
flush stream
generic prin character
generic prin double
generic prin null
generic prin pair
generic prin semaphore
Programming Language EuLisp version
Condition Index
arithmetic condition number
bad apply argument level
cannot convert to character spint
cannot update setter level
conversion condition convert
division by zero spint
dynamic multiply defined level
environment condition condition
execution condition condition
improper unquote splice level
incompatible method signature level
integer conversion overflow double
invalid operator level
no applicable method level
no converter convert
non congruent lambda lists level
no next method level
no setter level
no such character spint
not a character pair
nt character pair
old thread thread
scan mismatch formatted io
stream condition stream
syntax error stream
telos condition level
thread condition thread
unbound dynamic variable level
wrong condition class condition
wrong thread thread
Programming Language EuLisp version
Constant Index
input stream stream
io stream stream
least negative double float double
least positive double float double
maximum vector index vector
most negative double float double
most negative single precision integer spint
most positive double float double
most positive single precision integer spint
nil
ouput stream stream
pi elementary functions
t
ticks per second level
Programming Language EuLisp version
General Index
character
character
character extension glyph
characterp
character stream p
Common Lisp
class
constructor
null
primitive
self instantiated
abs class option
accessor class precedence list
acos class initargs
acosh class name
add method class of
allocate class precedence list
and class slot descriptions
applicable metho d CLOS
applicable metho d list close
applicable ob ject close semaphore
apply closure
apply method collection
asin comment
asinh comment begin glyph
assignment Common Lisp Error System
atan compatible superclasses p
atan compatible superclass p
atanh compliance
atom compute and ensure slot accessors
backquoting compute class precedence list
base compute constructor
arbitrary base literals compute defined slot description
limitation on input compute defined slot description class
binary literals compute discriminating function
binary difference compute inherited initargs
binary divide compute inherited slot descriptions
binary gcd compute initargs
binary lcm compute method lookup function
binary lt compute predicate
binary plus compute primitive reader using class
binary stream p compute primitive reader using slot description
binary times compute primitive writer using class
binding compute primitive writer using slot description
dynamically scop ed compute slot descriptions
mo dule compute slot reader
of mo dule names compute slot writer
top dynamic compute specialized slot description
binding form compute specialized slot description class
block cond
see also let cc condition
b o olean condition
de nition of continuable
b ound variable non continuabl e
call method condition message
call next method conditionp
Cambridge LISP con guration
car conformance
case sensitivity level
catch level
catenate level
cdr conforming pro cessor
ceiling conforming program
cerror conformity clause
character least negative double precision oat
Programming Language EuLisp version
least p ositive double precision oat dynamic scop e
maximum vector index dynamicall y closer
most negative double precision oat dynamic let
most negative single precision integer dynamic setq
most p ositive double precision oat elementary functions
most p ositive single precision integer empty list
congruent empty p
cons ensure slot reader
consp ensure slot writer
constant environmental error
de ned eq
literal implementation de n ed b ehaviour
constructor eql
continuation equal
conventions error
convert error
converter can b e signaled
converter character dynamic
converter double float environmental
converter function handler
converter integer signaled
converter pair static
converter single precision integer level
converter string level
copy level
copy alist libraries
copy list evenp
copy tree except
cos exp
cosh export
current thread export syntax
defclass expose
defcondition expt
defconstant extension
defgeneric extent
de ning form empty list
defclass oating p oint
defcondition integer
defconstant list
defgeneric null empty list
deflocal pair
defmacro string
defmetaclass vector
defstruct external representation see also prin and write
defun write
defvar file stream
deflocal file streamp
defmacro fill
defmetaclass filter
defmethod float
defmodule floatp
defstruct floor
defun flush
defvar form
direct instance format
direct slot description formatted io
direct sub class free variable
direct sup erclass function
discriminatio n accessor function
do calling
double oat standard function
double float up dator function
double float gcd
double float p generic arithmetic
dynamic generic function
dynamic environment discrimina tion
dynamic error lamb da list
dynamic extent generic function discriminating function
Programming Language EuLisp version
generic function domain LE LISP
generic function method class LeLisp
generic function method lookup function length
generic function methods let
generic function range let
generic labels let cc
generic lambda see also block and return from
generic prin level
level classes
generic read character
generic write double float
float
gensym integer
Haskell null
hexadecimal
pair
notation in strings semaphore
hexadecimal literals spint
identi er
stream
de nition of string
p eculiar identi ers symbol
syntax table
if thread
implementation de ned vector
b ehaviour of eq level mo dules
b ehaviour of equal
character
oating p oint precision collection
least negative double precision oat compare
least p ositive double precision oat
condition
maximum vector index convert
mo dule binding environment copy
most negative double precision oat
double
most negative single precision integer elementary functions
most p ositive double precision oat formatted io
most p ositive single precision integer level euli sp
representation of tables null
time units p er second numb er
unhandled conditions pair
improp er list
semaphore
inde nite extent spint
inde nite scop e stream
indirect instance
string
indirect slot description symb ol
indirect sub class table
single thread
inheritance graph vector
inherited slot description lexical environment
initarg lexical scop e
initform lexicall y closer
initfunction LISP VM
initializ ation list
initialize list
initialize instance empty
init list literal
inner dynamic
arbitrary base
inner lexical binary
input stream p character
instance hexadecimal
direct mo di cation of
indirect o ctal
instantiation graph quotation
integer local slot description
integerp log
InterLISP log
io stream p log
labels macro
lambda de nition by defmacro
lamb da list macro expansion see also syntax
lcm macro expression
Programming Language EuLisp version
macros see also syntax prop er list
make function call
make initialized vector quasiquotati on
map quasiquote
max abbreviation with
member quotation
metaclass quote
metho d abbreviation with
applicable quotient
bindings read
list of applicable reader
lo okup read unit
sp eci city reduce
metho d combination reduce
metho d function re ective
metho d lo okup remainder
metho d sp eci city remove method
method domain rename
method function return from
method function lambda see also let cc
method generic function round
method range scan
MicroCeyx scop e
min in labels expressions
mo dule of dynamic let bindings
environments of lambda bindings
imp orts of let cc binding
name bindings self instantiated class
modulo semaphore
multi metho d semaphore
negate semaphorep
negativep setq
new instance setter
next method p setter car
null setter cdr
null setter converter
null setter function
number setter primitive class of
numberp setter primitive ref
Oaklisp setter string ref
ob ject setter table ref
Ob jVLisp setter vector ref
o ctal literals shadow
oddp signal
only signature
open signum
open p sin
open semaphore single inheritance
or single precision integer
output stream p single precision integer
pair single precision integer
pair single precision integer p
pair sinh
peek unit size
positivep slot
primitive allocate accessor
primitive class of reader
primitive ref writer
prin slot description
constants direct
op erand indirect
op erator slot description list
symb ols slot option
pro cessor slot description
representation of semaphore slot description initfunction
representation of threads slot description name
gensym names slot description slot reader
progn slot description slot writer
Programming Language EuLisp version
sp ecial form table
call next method table
dynamic table delete
dynamic let tablep
table ref
dynamic setq
if tan
tanh
labels
inheritance
lambda
thread
let cc
thread
next method p
threadp
progn
thread reschedule
function call
thread start
quote
thread value
setq
throw
unwind protect
top dynamic
with handler
top lexical
sp ecialize
truncate
sp ecialize on
unless
sqrt
unquote
Standard ML
abbreviation with
standard mo dule
unquote splicing
static error
abbreviation to
stream
unwind protect
stream
variable
string
vector
string
vector
string
vector
hex insertion character
vectorp
string begin glyph
vector ref
string end glyph
wait
escaping in
when
hexadecimal notation in
de nition of
string escap e glyph
with handler
string append
write
string lt
writer
stringp
write unit
string ref
zerop
string slice
sub class
direct
indirect
sup erclass
direct
symb ol
symbol
symbol
symbol exists p
symbol name
symbolp
syntax
external representations
generic function lamb da list
identi er
lamb da list
character
constant
defmodule
double float
pair
single precision integer
string
symbol
unquote
unquote splicing
vector
syntax expansion
T