Schema Transformation Processors for Federated Objectbases
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Dotty Phantom Types (Technical Report)
Dotty Phantom Types (Technical Report) Nicolas Stucki Aggelos Biboudis Martin Odersky École Polytechnique Fédérale de Lausanne Switzerland Abstract 2006] and even a lightweight form of dependent types [Kise- Phantom types are a well-known type-level, design pattern lyov and Shan 2007]. which is commonly used to express constraints encoded in There are two ways of using phantoms as a design pattern: types. We observe that in modern, multi-paradigm program- a) relying solely on type unication and b) relying on term- ming languages, these encodings are too restrictive or do level evidences. According to the rst way, phantoms are not provide the guarantees that phantom types try to en- encoded with type parameters which must be satised at the force. Furthermore, in some cases they introduce unwanted use-site. The declaration of turnOn expresses the following runtime overhead. constraint: if the state of the machine, S, is Off then T can be We propose a new design for phantom types as a language instantiated, otherwise the bounds of T are not satisable. feature that: (a) solves the aforementioned issues and (b) makes the rst step towards new programming paradigms type State; type On <: State; type Off <: State class Machine[S <: State] { such as proof-carrying code and static capabilities. This pa- def turnOn[T >: S <: Off] = new Machine[On] per presents the design of phantom types for Scala, as im- } new Machine[Off].turnOn plemented in the Dotty compiler. An alternative way to encode the same constraint is by 1 Introduction using an implicit evidence term of type =:=, which is globally Parametric polymorphism has been one of the most popu- available. -
Cross-Platform Language Design
Cross-Platform Language Design THIS IS A TEMPORARY TITLE PAGE It will be replaced for the final print by a version provided by the service academique. Thèse n. 1234 2011 présentée le 11 Juin 2018 à la Faculté Informatique et Communications Laboratoire de Méthodes de Programmation 1 programme doctoral en Informatique et Communications École Polytechnique Fédérale de Lausanne pour l’obtention du grade de Docteur ès Sciences par Sébastien Doeraene acceptée sur proposition du jury: Prof James Larus, président du jury Prof Martin Odersky, directeur de thèse Prof Edouard Bugnion, rapporteur Dr Andreas Rossberg, rapporteur Prof Peter Van Roy, rapporteur Lausanne, EPFL, 2018 It is better to repent a sin than regret the loss of a pleasure. — Oscar Wilde Acknowledgments Although there is only one name written in a large font on the front page, there are many people without which this thesis would never have happened, or would not have been quite the same. Five years is a long time, during which I had the privilege to work, discuss, sing, learn and have fun with many people. I am afraid to make a list, for I am sure I will forget some. Nevertheless, I will try my best. First, I would like to thank my advisor, Martin Odersky, for giving me the opportunity to fulfill a dream, that of being part of the design and development team of my favorite programming language. Many thanks for letting me explore the design of Scala.js in my own way, while at the same time always being there when I needed him. -
Blossom: a Language Built to Grow
Macalester College DigitalCommons@Macalester College Mathematics, Statistics, and Computer Science Honors Projects Mathematics, Statistics, and Computer Science 4-26-2016 Blossom: A Language Built to Grow Jeffrey Lyman Macalester College Follow this and additional works at: https://digitalcommons.macalester.edu/mathcs_honors Part of the Computer Sciences Commons, Mathematics Commons, and the Statistics and Probability Commons Recommended Citation Lyman, Jeffrey, "Blossom: A Language Built to Grow" (2016). Mathematics, Statistics, and Computer Science Honors Projects. 45. https://digitalcommons.macalester.edu/mathcs_honors/45 This Honors Project - Open Access is brought to you for free and open access by the Mathematics, Statistics, and Computer Science at DigitalCommons@Macalester College. It has been accepted for inclusion in Mathematics, Statistics, and Computer Science Honors Projects by an authorized administrator of DigitalCommons@Macalester College. For more information, please contact [email protected]. In Memory of Daniel Schanus Macalester College Department of Mathematics, Statistics, and Computer Science Blossom A Language Built to Grow Jeffrey Lyman April 26, 2016 Advisor Libby Shoop Readers Paul Cantrell, Brett Jackson, Libby Shoop Contents 1 Introduction 4 1.1 Blossom . .4 2 Theoretic Basis 6 2.1 The Potential of Types . .6 2.2 Type basics . .6 2.3 Subtyping . .7 2.4 Duck Typing . .8 2.5 Hindley Milner Typing . .9 2.6 Typeclasses . 10 2.7 Type Level Operators . 11 2.8 Dependent types . 11 2.9 Hoare Types . 12 2.10 Success Types . 13 2.11 Gradual Typing . 14 2.12 Synthesis . 14 3 Language Description 16 3.1 Design goals . 16 3.2 Type System . 17 3.3 Hello World . -
Webassembly Specification
WebAssembly Specification Release 1.1 WebAssembly Community Group Andreas Rossberg (editor) Mar 11, 2021 Contents 1 Introduction 1 1.1 Introduction.............................................1 1.2 Overview...............................................3 2 Structure 5 2.1 Conventions.............................................5 2.2 Values................................................7 2.3 Types.................................................8 2.4 Instructions.............................................. 11 2.5 Modules............................................... 15 3 Validation 21 3.1 Conventions............................................. 21 3.2 Types................................................. 24 3.3 Instructions.............................................. 27 3.4 Modules............................................... 39 4 Execution 47 4.1 Conventions............................................. 47 4.2 Runtime Structure.......................................... 49 4.3 Numerics............................................... 56 4.4 Instructions.............................................. 76 4.5 Modules............................................... 98 5 Binary Format 109 5.1 Conventions............................................. 109 5.2 Values................................................ 111 5.3 Types................................................. 112 5.4 Instructions.............................................. 114 5.5 Modules............................................... 120 6 Text Format 127 6.1 Conventions............................................ -
1 Intro to ML
1 Intro to ML 1.1 Basic types Need ; after expression - 42 = ; val it = 42: int -7+1; val it =8: int Can reference it - it+2; val it = 10: int - if it > 100 then "big" else "small"; val it = "small": string Different types for each branch. What will happen? if it > 100 then "big" else 0; The type checker will complain that the two branches have different types, one is string and the other is int If with then but no else. What will happen? if 100>1 then "big"; There is not if-then in ML; must use if-then-else instead. Mixing types. What will happen? What is this called? 10+ 2.5 In many programming languages, the int will be promoted to a float before the addition is performed, and the result is 12.5. In ML, this type coercion (or type promotion) does not happen. Instead, the type checker will reject this expression. div for integers, ‘/ for reals - 10 div2; val it =5: int - 10.0/ 2.0; val it = 5.0: real 1 1.1.1 Booleans 1=1; val it = true : bool 1=2; val it = false : bool Checking for equality on reals. What will happen? 1.0=1.0; Cannot check equality of reals in ML. Boolean connectives are a bit weird - false andalso 10>1; val it = false : bool - false orelse 10>1; val it = true : bool 1.1.2 Strings String concatenation "University "^ "of"^ " Oslo" 1.1.3 Unit or Singleton type • What does the type unit mean? • What is it used for? • What is its relation to the zero or bottom type? - (); val it = () : unit https://en.wikipedia.org/wiki/Unit_type https://en.wikipedia.org/wiki/Bottom_type The boolean type is inhabited by two values: true and false. -
Distributive Disjoint Polymorphism for Compositional Programming
Distributive Disjoint Polymorphism for Compositional Programming Xuan Bi1, Ningning Xie1, Bruno C. d. S. Oliveira1, and Tom Schrijvers2 1 The University of Hong Kong, Hong Kong, China fxbi,nnxie,[email protected] 2 KU Leuven, Leuven, Belgium [email protected] Abstract. Popular programming techniques such as shallow embeddings of Domain Specific Languages (DSLs), finally tagless or object algebras are built on the principle of compositionality. However, existing program- ming languages only support simple compositional designs well, and have limited support for more sophisticated ones. + This paper presents the Fi calculus, which supports highly modular and compositional designs that improve on existing techniques. These im- provements are due to the combination of three features: disjoint inter- section types with a merge operator; parametric (disjoint) polymorphism; and BCD-style distributive subtyping. The main technical challenge is + Fi 's proof of coherence. A naive adaptation of ideas used in System F's + parametricity to canonicity (the logical relation used by Fi to prove co- herence) results in an ill-founded logical relation. To solve the problem our canonicity relation employs a different technique based on immediate substitutions and a restriction to predicative instantiations. Besides co- herence, we show several other important meta-theoretical results, such as type-safety, sound and complete algorithmic subtyping, and decidabil- ity of the type system. Remarkably, unlike F<:'s bounded polymorphism, + disjoint polymorphism in Fi supports decidable type-checking. 1 Introduction Compositionality is a desirable property in programming designs. Broadly de- fined, it is the principle that a system should be built by composing smaller sub- systems. -
Bs-6026-0512E.Pdf
THERMAL PRINTER SPEC BAS - 6026 1. Basic Features 1.) Type : PANEL Mounting or DESK top type 2.) Printing Type : THERMAL PRINT 3.) Printing Speed : 25mm / SEC 4.) Printing Column : 24 COLUMNS 5.) FONT : 24 X 24 DOT MATRIX 6.) Character : English, Numeric & Others 7.) Paper width : 57.5mm ± 0.5mm 8.) Character Size : 5times enlarge possible 9.) INTERFACE : CENTRONICS PARALLEL I/F SERIAL I/F 10.) DIMENSION : 122(W) X 90(D) X 129(H) 11.) Operating Temperature range : 0℃ - 50℃ 12.) Storage Temperature range : -20℃ - 70℃ 13.) Outlet Power : DC 12V ( 1.6 A )/ DC 5V ( 2.5 A) 14.) Application : Indicator, Scale, Factory automation equipments and any other data recording, etc.,, - 1 - 1) SERIAL INTERFACE SPECIFICATION * CONNECTOR : 25 P FEMALE PRINTER : 4 P CONNECTOR 3 ( TXD ) ----------------------- 2 ( RXD ) 2 2 ( RXD ) ----------------------- 1 ( TXD ) 3 7 ( GND ) ----------------------- 4 ( GND ) 5 DIP SWITCH BUAD RATE 1 2 3 ON ON ON 150 OFF ON ON 300 ON OFF ON 600 OFF OFF ON 1200 ON ON OFF 2400 OFF ON OFF 4800 ON OFF OFF 9600 OFF OFF OFF 19200 2) BAUD RATE SELECTION * PROTOCOL : XON / XOFF Type DIP SWITCH (4) ON : Combination type * DATA BIT : 8 BIT STOP BIT : 1 STOP BIT OFF: Complete type PARITY CHECK : NO PARITY * DEFAULT VALUE : BAUD RATE (9600 BPS) - 2 - PRINTING COMMAND * Explanation Command is composed of One Byte Control code and ESC code. This arrangement is started with ESC code which is connected by character & numeric code The control code in Printer does not be still in standardization (ESC Control Code). All printers have a code structure by themselves. -
Foundations of Path-Dependent Types
Foundations of Path-Dependent Types Nada Amin∗ Tiark Rompf †∗ Martin Odersky∗ ∗EPFL: {first.last}@epfl.ch yOracle Labs: {first.last}@oracle.com Abstract 1. Introduction A scalable programming language is one in which the same A scalable programming language is one in which the same concepts can describe small as well as large parts. Towards concepts can describe small as well as large parts. Towards this goal, Scala unifies concepts from object and module this goal, Scala unifies concepts from object and module systems. An essential ingredient of this unification is the systems. An essential ingredient of this unification is to concept of objects with type members, which can be ref- support objects that contain type members in addition to erenced through path-dependent types. Unfortunately, path- fields and methods. dependent types are not well-understood, and have been a To make any use of type members, programmers need a roadblock in grounding the Scala type system on firm the- way to refer to them. This means that types must be able ory. to refer to objects, i.e. contain terms that serve as static We study several calculi for path-dependent types. We approximation of a set of dynamic objects. In other words, present µDOT which captures the essence – DOT stands some level of dependent types is required; the usual notion for Dependent Object Types. We explore the design space is that of path-dependent types. bottom-up, teasing apart inherent from accidental complexi- Despite many attempts, Scala’s type system has never ties, while fully mechanizing our models at each step. -
Local Type Inference
Local Type Inference BENJAMIN C. PIERCE University of Pennsylvania and DAVID N. TURNER An Teallach, Ltd. We study two partial type inference methods for a language combining subtyping and impredica- tive polymorphism. Both methods are local in the sense that missing annotations are recovered using only information from adjacent nodes in the syntax tree, without long-distance constraints such as unification variables. One method infers type arguments in polymorphic applications using a local constraint solver. The other infers annotations on bound variables in function abstractions by propagating type constraints downward from enclosing application nodes. We motivate our design choices by a statistical analysis of the uses of type inference in a sizable body of existing ML code. Categories and Subject Descriptors: D.3.1 [Programming Languages]: Formal Definitions and Theory General Terms: Languages, Theory Additional Key Words and Phrases: Polymorphism, subtyping, type inference 1. INTRODUCTION Most statically typed programming languages offer some form of type inference, allowing programmers to omit type annotations that can be recovered from context. Such a facility can eliminate a great deal of needless verbosity, making programs easier both to read and to write. Unfortunately, type inference technology has not kept pace with developments in type systems. In particular, the combination of subtyping and parametric polymorphism has been intensively studied for more than a decade in calculi such as System F≤ [Cardelli and Wegner 1985; Curien and Ghelli 1992; Cardelli et al. 1994], but these features have not yet been satisfactorily This is a revised and extended version of a paper presented at the 25th ACM SIGPLAN-SIGACT Symposium on Principles of Programming Languages (POPL), 1998. -
The Essence of Dependent Object Types⋆
The Essence of Dependent Object Types? Nada Amin∗, Samuel Grütter∗, Martin Odersky∗, Tiark Rompf †, and Sandro Stucki∗ ∗ EPFL, Switzerland: {first.last}@epfl.ch † Purdue University, USA: {first}@purdue.edu Abstract. Focusing on path-dependent types, the paper develops foun- dations for Scala from first principles. Starting from a simple calculus D<: of dependent functions, it adds records, intersections and recursion to arrive at DOT, a calculus for dependent object types. The paper shows an encoding of System F with subtyping in D<: and demonstrates the expressiveness of DOT by modeling a range of Scala constructs in it. Keywords: Calculus, Dependent Types, Scala 1 Introduction While hiking together in the French alps in 2013, Martin Odersky tried to explain to Phil Wadler why languages like Scala had foundations that were not directly related via the Curry-Howard isomorphism to logic. This did not go over well. As you would expect, Phil strongly disapproved. He argued that anything that was useful should have a grounding in logic. In this paper, we try to approach this goal. We will develop a foundation for Scala from first principles. Scala is a func- tional language that expresses central aspects of modules as first-class terms and types. It identifies modules with objects and signatures with traits. For instance, here is a trait Keys that defines an abstract type Key and a way to retrieve a key from a string. trait Keys { type Key def key(data: String): Key } A concrete implementation of Keys could be object HashKeys extends Keys { type Key = Int def key(s: String) = s.hashCode } ? This is a revised version of a paper presented at WF ’16. -
Cormac Flanagan Fritz Henglein Nate Nystrom Gavin Bierman Jan Vitek Gilad Bracha Philip Wadler Jeff Foster Tobias Wrigstad Peter Thiemann Sam Tobin-Hochstadt
PC: Amal Ahmed SC: Matthias Felleisen Robby Findler (chair) Cormac Flanagan Fritz Henglein Nate Nystrom Gavin Bierman Jan Vitek Gilad Bracha Philip Wadler Jeff Foster Tobias Wrigstad Peter Thiemann Sam Tobin-Hochstadt Organizers: Tobias Wrigstad and Jan Vitek Schedule Schedule . 3 8:30 am – 10:30 am: Invited Talk: Scripting in a Concurrent World . 5 Language with a Pluggable Type System and Optional Runtime Monitoring of Type Errors . 7 Position Paper: Dynamically Inferred Types for Dynamic Languages . 19 10:30 am – 11:00 am: Coffee break 11:00 am – 12:30 pm: Gradual Information Flow Typing . 21 Type Inference with Run-time Logs . 33 The Ciao Approach to the Dynamic vs. Static Language Dilemma . 47 12:30 am – 2:00 pm: Lunch Invited Talk: Scripting in a Concurrent World John Field IBM Research As scripting languages are used to build increasingly complex systems, they must even- tually confront concurrency. Concurrency typically arises from two distinct needs: han- dling “naturally” concurrent external (human- or software-generated) events, and en- hancing application performance. Concurrent applications are difficult to program in general; these difficulties are multiplied in a distributed setting, where partial failures are common and where resources cannot be centrally managed. The distributed sys- tems community has made enormous progress over the past few decades designing specialized systems that scale to handle millions of users and petabytes of data. How- ever, combining individual systems into composite applications that are scalable—not to mention reliable, secure, and easy to develop maintain—remains an enormous chal- lenge. This is where programming languages should be able to help: good languages are designed to facilitate composing large applications from smaller components and for reasoning about the behavior of applications modularly. -
Download the JSR-000202 Java Class File Specification
CHAPTER 4 The class File Format THIS chapter describes the Java virtual machine class file format. Each class file contains the definition of a single class or interface. Although a class or interface need not have an external representation literally contained in a file (for instance, because the class is generated by a class loader), we will colloquially refer to any valid representation of a class or interface as being in the class file format. A class file consists of a stream of 8-bit bytes. All 16-bit, 32-bit, and 64-bit quantities are constructed by reading in two, four, and eight consecutive 8-bit bytes, respectively. Multibyte data items are always stored in big-endian order, where the high bytes come first. In the Java and Java 2 platforms, this format is supported by interfaces java.io.DataInput and java.io.DataOutput and classes such as java.io.DataInputStream and java.io.DataOutputStream. This chapter defines its own set of data types representing class file data: The types u1, u2, and u4 represent an unsigned one-, two-, or four-byte quantity, respectively. In the Java and Java 2 platforms, these types may be read by methods such as readUnsignedByte, readUnsignedShort, and readInt of the interface java.io.DataInput. This chapter presents the class file format using pseudostructures written in a C- like structure notation. To avoid confusion with the fields of classes and class instances, etc., the contents of the structures describing the class file format are referred to as items. Successive items are stored in the class file sequentially, without padding or alignment.