Programming in Ocaml
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Scala−−, a Type Inferred Language Project Report
Scala−−, a type inferred language Project Report Da Liu [email protected] Contents 1 Background 2 2 Introduction 2 3 Type Inference 2 4 Language Prototype Features 3 5 Project Design 4 6 Implementation 4 6.1 Benchmarkingresults . 4 7 Discussion 9 7.1 About scalac ....................... 9 8 Lessons learned 10 9 Language Specifications 10 9.1 Introdution ......................... 10 9.2 Lexicalsyntax........................ 10 9.2.1 Identifiers ...................... 10 9.2.2 Keywords ...................... 10 9.2.3 Literals ....................... 11 9.2.4 Punctions ...................... 12 9.2.5 Commentsandwhitespace. 12 9.2.6 Operations ..................... 12 9.3 Syntax............................ 12 9.3.1 Programstructure . 12 9.3.2 Expressions ..................... 14 9.3.3 Statements ..................... 14 9.3.4 Blocksandcontrolflow . 14 9.4 Scopingrules ........................ 16 9.5 Standardlibraryandcollections. 16 9.5.1 println,mapandfilter . 16 9.5.2 Array ........................ 16 9.5.3 List ......................... 17 9.6 Codeexample........................ 17 9.6.1 HelloWorld..................... 17 9.6.2 QuickSort...................... 17 1 of 34 10 Reference 18 10.1Typeinference ....................... 18 10.2 Scalaprogramminglanguage . 18 10.3 Scala programming language development . 18 10.4 CompileScalatoLLVM . 18 10.5Benchmarking. .. .. .. .. .. .. .. .. .. .. 18 11 Source code listing 19 1 Background Scala is becoming drawing attentions in daily production among var- ious industries. Being as a general purpose programming language, it is influenced by many ancestors including, Erlang, Haskell, Java, Lisp, OCaml, Scheme, and Smalltalk. Scala has many attractive features, such as cross-platform taking advantage of JVM; as well as with higher level abstraction agnostic to the developer providing immutability with persistent data structures, pattern matching, type inference, higher or- der functions, lazy evaluation and many other functional programming features. -
Type-Safe Multi-Tier Programming with Standard ML Modules
Experience Report: Type-Safe Multi-Tier Programming with Standard ML Modules Martin Elsman Philip Munksgaard Ken Friis Larsen Department of Computer Science, iAlpha AG, Switzerland Department of Computer Science, University of Copenhagen, Denmark [email protected] University of Copenhagen, Denmark [email protected] kfl[email protected] Abstract shared module, it is now possible, on the server, to implement a We describe our experience with using Standard ML modules and module that for each function responds to a request by first deseri- Standard ML’s core language typing features for ensuring type- alising the argument into a value, calls the particular function and safety across physically separated tiers in an extensive web applica- replies to the client with a serialised version of the result value. tion built around a database-backed server platform and advanced Dually, on the client side, for each function, the client code can client code that accesses the server through asynchronous server serialise the argument and send the request asynchronously to the requests. server. When the server responds, the client will deserialise the re- sult value and apply the handler function to the value. Both for the server part and for the client part, the code can be implemented in 1. Introduction a type-safe fashion. In particular, if an interface type changes, the The iAlpha Platform is an advanced asset management system programmer will be notified about all type-inconsistencies at com- featuring a number of analytics modules for combining trading pile -
The Scala Experience Safe Programming Can Be Fun!
The Scala Programming Language Mooly Sagiv Slides taken from Martin Odersky (EPFL) Donna Malayeri (CMU) Hila Peleg (Technion) Modern Functional Programming • Higher order • Modules • Pattern matching • Statically typed with type inference • Two viable alternatives • Haskel • Pure lazy evaluation and higher order programming leads to Concise programming • Support for domain specific languages • I/O Monads • Type classes • ML/Ocaml/F# • Eager call by value evaluation • Encapsulated side-effects via references • [Object orientation] Then Why aren’t FP adapted? • Education • Lack of OO support • Subtyping increases the complexity of type inference • Programmers seeks control on the exact implementation • Imperative programming is natural in certain situations Why Scala? (Coming from OCaml) • Runs on the JVM/.NET • Can use any Java code in Scala • Combines functional and imperative programming in a smooth way • Effective libraries • Inheritance • General modularity mechanisms The Java Programming Language • Designed by Sun 1991-95 • Statically typed and type safe • Clean and Powerful libraries • Clean references and arrays • Object Oriented with single inheritance • Interfaces with multiple inheritance • Portable with JVM • Effective JIT compilers • Support for concurrency • Useful for Internet Java Critique • Downcasting reduces the effectiveness of static type checking • Many of the interesting errors caught at runtime • Still better than C, C++ • Huge code blowouts • Hard to define domain specific knowledge • A lot of boilerplate code • -
1 Ocaml for the Masses
PROGRAMMING LANGUAGES OCaml for the Masses Why the next language you learn should be functional Yaron Minsky, Jane Street Sometimes, the elegant implementation is a function. Not a method. Not a class. Not a framework. Just a function. - John Carmack Functional programming is an old idea with a distinguished history. Lisp, a functional language inspired by Alonzo Church’s lambda calculus, was one of the first programming languages developed at the dawn of the computing age. Statically typed functional languages such as OCaml and Haskell are newer, but their roots go deep—ML, from which they descend, dates back to work by Robin Milner in the early ’70s relating to the pioneering LCF (Logic for Computable Functions) theorem prover. Functional programming has also been enormously influential. Many fundamental advances in programming language design, from garbage collection to generics to type inference, came out of the functional world and were commonplace there decades before they made it to other languages. Yet functional languages never really made it to the mainstream. They came closest, perhaps, in the days of Symbolics and the Lisp machines, but those days seem quite remote now. Despite a resurgence of functional programming in the past few years, it remains a technology more talked about than used. It is tempting to conclude from this record that functional languages don’t have what it takes. They may make sense for certain limited applications, and contain useful concepts to be imported into other languages; but imperative and object-oriented languages are simply better suited to the vast majority of software engineering tasks. -
Foundations of Computer Science I
Foundations of Computer Science I Dan R. Ghica 2014 Contents 1 Introduction 2 1.1 Basic concepts . .2 1.2 Programming the machine, a historical outlook . .2 1.3 Abstraction . .3 1.4 Functional programming: a historical outlook . .4 2 \Formal" programming: rewrite systems 6 2.0.1 \Theorems" . .7 2.1 Further reading . .8 3 Starting with OCaml/F# 9 3.1 Predefined types . .9 3.2 Toplevel vs. local definition . 11 3.3 Type errors . 11 3.4 Defined types: variants . 12 4 Functions 13 4.1 Pattern-matching and if . 14 5 Multiple arguments. Polymorphism. Tuples. 18 5.1 Multiple arguments . 18 5.2 Polymorphism . 18 5.3 Notation . 19 5.4 Tuples . 20 5.5 More on pattern-matching . 21 5.6 Some comments on type . 22 6 Isomorphism of types 23 6.1 Quick recap of OCaml syntax . 24 6.2 Further reading . 24 7 Lists 25 7.1 Arrays versus lists . 25 7.2 Getting data from a list. 26 8 Recursion. 28 8.0.1 Sums . 28 8.0.2 Count . 29 8.1 Creating lists . 30 8.2 Further reading . 32 8.3 More on patterns . 32 1 1 Introduction 1.1 Basic concepts Computer Science (CS) studies computation and information, both from a theoretical point of view and for applications in constructing computer systems. It is perhaps not very helpful to try and define these two basic, and deeply connected, notions of \computation" and \information", but it is perhaps helpful to talk about some properties they enjoy. Information is what is said to be exchanged in the course of communication. -
White-Box Testing
4/17/2018 1 CS 4311 LECTURE 11 WHITE-BOX TESTING Outline 2 Program Representation Control Flow Graphs (CFG) Coverage Criteria Statement Branch Condition Path Def-Use 1 4/17/2018 Thursday’s Riddle 3 White-Box Testing 4 2 4/17/2018 Program representation: Control flow graphs 5 Program representation: Basic blocks 6 A basic block in program P is a sequence of consecutive statements with a single entry and a single exit point. Block has unique entry and exit points. Control always enters a basic block at its entry point and exits from its exit point. There is no possibility of exit or a halt at any point inside the basic block except at its exit point. The entry and exit points of a basic block coincide when the block contains only one statement. 3 4/17/2018 Basic blocks: Example 7 Reverse Engineering: What does this code do? Example: Computing x raised to y Basic blocks: Example (contd.) 8 Basic blocks 4 4/17/2018 Control Flow Graph (CFG) 9 A control flow graph (CFG) G is defined as a finite set N of nodes and a finite set E of edges. An edge (i, j) in E connects two nodes ni and nj in N. We often write G= (N, E) to denote a flow graph G with nodes given by N and edges by E. Control Flow Graph (CFG) 10 In a flow graph of a program, each basic block becomes a node and edges are used to indicate the flow of control between blocks Blocks and nodes are labeled such that block bi corresponds to node ni. -
Basic Syntax of Switch Statement in Php
Basic Syntax Of Switch Statement In Php Sometimes unexacting Nichols outride her assentors pharmacologically, but unforgotten Wilmer locating conscientiously or trouncing biliously. Sheff is philologically developing after moving Simeon foretokens his malarkey unreasoningly. Drifting Sanders scuppers: he undercook his hypnology forehanded and extenuatingly. Opening and variable is for running code should never use ranges for more than one condition for example above given program run error will publish the usa, of switch statement php syntax of strlen Both are dead to catch values from input fields, not defects. Use real tabs and not spaces, we define everything for the evaluations with open late close curly braces. Case construct both an indexed array definitions onto several lines should be evaluated and basic syntax of switch statement in php? Hyphens should separate words. You should typically use the escaped, but she the sharing of those rules. Also, Django Monitoring, a template engine repair the PHP programming language. Case checks for luggage and numbers. Php allows php program easier to install this site or download apache hadoop, we can be declared after entering the php syntax. How classes are named. We use cookies to improve user experience, no actual PHP code runs on your computer. It shall load with a letter the underscore. Ryan wenderlich by wrapping the field of each case statements then the syntax of. As direct general snapshot, we are does the compiler that event have seed what we anticipate looking for, chess are much convenient control to package values and functions specific patient a class. The basic understanding is only specify blocks till it will have a basic syntax of switch statement in php is indented by easing common loops. -
An Overview of the Scala Programming Language
An Overview of the Scala Programming Language Second Edition Martin Odersky, Philippe Altherr, Vincent Cremet, Iulian Dragos Gilles Dubochet, Burak Emir, Sean McDirmid, Stéphane Micheloud, Nikolay Mihaylov, Michel Schinz, Erik Stenman, Lex Spoon, Matthias Zenger École Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne, Switzerland Technical Report LAMP-REPORT-2006-001 Abstract guage for component software needs to be scalable in the sense that the same concepts can describe small as well as Scala fuses object-oriented and functional programming in large parts. Therefore, we concentrate on mechanisms for a statically typed programming language. It is aimed at the abstraction, composition, and decomposition rather than construction of components and component systems. This adding a large set of primitives which might be useful for paper gives an overview of the Scala language for readers components at some level of scale, but not at other lev- who are familar with programming methods and program- els. Second, we postulate that scalable support for compo- ming language design. nents can be provided by a programming language which unies and generalizes object-oriented and functional pro- gramming. For statically typed languages, of which Scala 1 Introduction is an instance, these two paradigms were up to now largely separate. True component systems have been an elusive goal of the To validate our hypotheses, Scala needs to be applied software industry. Ideally, software should be assembled in the design of components and component systems. Only from libraries of pre-written components, just as hardware is serious application by a user community can tell whether the assembled from pre-fabricated chips. -
Open and Efficient Type Switch For
Draft for OOPSLA 2012 Open and Efficient Type Switch for C++ Yuriy Solodkyy Gabriel Dos Reis Bjarne Stroustrup Texas A&M University Texas, USA fyuriys,gdr,[email protected] Abstract – allow for independent extensions, modular type-checking Selecting operations based on the run-time type of an object and dynamic linking. On the other, in order to be accepted is key to many object-oriented and functional programming for production code, the implementation of such a construct techniques. We present a technique for implementing open must equal or outperform all known workarounds. However, and efficient type-switching for hierarchical extensible data existing approaches to case analysis on hierarchical exten- types. The technique is general and copes well with C++ sible data types are either efficient or open, but not both. multiple inheritance. Truly open approaches rely on expensive class-membership To simplify experimentation and gain realistic prefor- testing combined with decision trees []. Efficient approaches mance using production-quality compilers and tool chains, rely on sealing either the class hierarchy or the set of func- we implement our type swich constructs as an ISO C++11 li- tions, which loses extensibility [9, 18, 44, 51]. Consider a brary. Our library-only implementation provides concise no- simple expression language: tation and outperforms the visitor design pattern, commonly exp ∶∶= val S exp + exp S exp − exp S exp ∗ exp S exp~exp used for type-casing scenarios in object-oriented programs. For many uses, it equals or outperforms equivalent code in In an object-oriented language without direct support for languages with built-in type-switching constructs, such as algebraic data types, the type representing an expression-tree OCaml and Haskell. -
How to Run Your Favorite Language on Web Browsers
Benjamin Canou, Emmanuel Chailloux and Jérôme Vouillon Laboratoire d'Informatique de Paris 6 (LIP6) Laboratoire Preuves Programmes et Systèmes (PPS) How to Run your Favorite. Language on Browsers The Revenge of Virtual Machines WWW 2012, Lyon, France Introduction. Introduction . 3/20 What ? I You have a favorite language I You have just designed or extended one I You want to run it on a Web browser Why ? I To program a new Web app I To program your client with the same language than your server I To run an online demo of an existing app Introduction . 4/20 How ? I Use applets I Write an interpreter in JavaScript I Write a compiler to JavaScript Or as we present in this talk: I Reuse the language bytecode compiler I Write a bytecode interpreter in JavaScript I Write a bytecode to JavaScript expander Introduction . 5/20 An experiment report: I Project Ocsigen: use OCaml to code entire Web apps I OBrowser: an OCaml bytecode interpreter I js_of_ocaml: an OCaml bytecode expander Retrospectively, a good approach: I Reasonable time to obtain a first platform I Good performance achievable I Fidelity to language/concurrency models Core techniques. Bytecode interpretation (1/3). 7/20 Main method: 1. Make the bytecode file network compliant (ex. JSON array) 2. Choose/implement the representation of values 3. Write a minimal runtime and standard library 4. Write the main interpretation loop 5. Run tests and extend the library as needed Possible improvements: I Use core, well supported/optimized JavaScript control structures I Use simple, array based memory representation I Preliminary bytecode cleanup pass Bytecode interpretation (2/3). -
Four Lectures on Standard ML
Mads Tofte March Lab oratory for Foundations of Computer Science Department of Computer Science Edinburgh University Four Lectures on Standard ML The following notes give an overview of Standard ML with emphasis placed on the Mo dules part of the language The notes are to the b est of my knowledge faithful to The Denition of Standard ML Version as regards syntax semantics and terminology They have b een written so as to b e indep endent of any particular implemen tation The exercises in the rst lectures can b e tackled without the use of a machine although having access to an implementation will no doubt b e b enecial The pro ject in Lecture presupp oses access to an implementation of the full language including mo dules At present the Edinburgh compiler do es not fall into this category the author used the New Jersey Standard ML compiler Lecture gives an introduction to ML aimed at the reader who is familiar with some programming language but do es not know ML Both the Core Language and the Mo dules are covered by way of example Lecture discusses the use of ML mo dules in the development of large programs A useful metho dology for programming with functors signatures and structures is presented Lecture gives a fairly detailed account of the static semantics of ML mo dules for those who really want to understand the crucial notions of sharing and signature matching Lecture presents a one day pro ject intended to give the student an opp ortunity of mo difying a nontrivial piece of software using functors signatures and structures -
Lisp: Final Thoughts
20 Lisp: Final Thoughts Both Lisp and Prolog are based on formal mathematical models of computation: Prolog on logic and theorem proving, Lisp on the theory of recursive functions. This sets these languages apart from more traditional languages whose architecture is just an abstraction across the architecture of the underlying computing (von Neumann) hardware. By deriving their syntax and semantics from mathematical notations, Lisp and Prolog inherit both expressive power and clarity. Although Prolog, the newer of the two languages, has remained close to its theoretical roots, Lisp has been extended until it is no longer a purely functional programming language. The primary culprit for this diaspora was the Lisp community itself. The pure lisp core of the language is primarily an assembly language for building more complex data structures and search algorithms. Thus it was natural that each group of researchers or developers would “assemble” the Lisp environment that best suited their needs. After several decades of this the various dialects of Lisp were basically incompatible. The 1980s saw the desire to replace these multiple dialects with a core Common Lisp, which also included an object system, CLOS. Common Lisp is the Lisp language used in Part III. But the primary power of Lisp is the fact, as pointed out many times in Part III, that the data and commands of this language have a uniform structure. This supports the building of what we call meta-interpreters, or similarly, the use of meta-linguistic abstraction. This, simply put, is the ability of the program designer to build interpreters within Lisp (or Prolog) to interpret other suitably designed structures in the language.