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List Comprehension
A list comprehension is a Syntax of programming languages, syntactic construct available in some programming languages for creating a list based on existing list (computing), lists. It follows the form of the mathematical ''set-builder notation'' (''set comprehension'') as distinct from the use of Map (higher-order function), map and Filter (higher-order function), filter functions. Overview Consider the following example in set-builder notation. :S=\ or often :S=\ This can be read, "S is the set of all numbers "2 times x" SUCH THAT x is an ELEMENT or MEMBER of the set of natural numbers (\mathbb), AND x squared is greater than 3." The smallest natural number, x = 1, fails to satisfy the condition x2>3 (the condition 12>3 is false) so 2 ·1 is not included in S. The next natural number, 2, does satisfy the condition (22>3) as does every other natural number. Thus x consists of 2, 3, 4, 5... Since the set consists of all numbers "2 times x" it is given by S = . S is, in other wor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Syntax Of Programming Languages
Internet, In computer science, the syntax of a computer language is the rules that defines the combinations of symbols that are considered to be correctly structured Statement (computer science), statements or Expression (computer science), expressions in that language. This applies both to programming languages, where the document represents source code, and to markup languages, where the document represents data. The syntax of a language defines its surface form. Text-based user interface, Text-based computer languages are based on sequences of Character (computing), characters, while visual programming languages are based on the spatial layout and connections between symbols (which may be textual or graphical). Documents that are syntactically invalid are said to have a syntax error. When designing the syntax of a language, a designer might start by writing down examples of both legal and illegal String (computer science), strings, before trying to figure out the general rules ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Darlington
John Darlington is a British academic, researcher and author. He is an Emeritus Professor at Imperial College London. He was Director of the London e-Science Centre and was head of the Functional Programming and Social Computing Sections at Imperial. Darlington is known for the early work he did on program transformation and functional programming. In his thesis in 1972, Darlington popularized the idea of program transformation, i.e. manipulating programs into alternative forms, preserving their semantics while altering their operational characteristics. Early life and education Darlington completed his B.Sc. (Econ) in 1969 from the London School of Economics and his Ph.D. in Artificial Intelligence from the Department of Machine Intelligence at the University of Edinburgh in 1973. He was a Research Fellow at the Edinburgh University from 1973 to 1977. Later he was a Visiting Research Fellow at IBM Yorktown Heights and the Stanford Research Institute. Career In 1977, Darling ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
W3Schools
W3Schools is a freemium educational website for learning coding online. Initially released in 1998, it derives its name from the World Wide Web but is not affiliated with the W3 Consortium. W3Schools offers courses covering all aspects of web development. W3Schools also publishes free HTML templates. It is run by Refsnes Data in Norway. It has an online text editor called TryIt Editor, and readers can edit examples and run the code in a test environment. Functions On the site, source code examples with explanations are shown free of charge in English, most of which can also be edited and executed interactively in a live editor. Other important code elements are hidden so that the user can focus on the code shown (developer sandbox). The tutorials are divided into individual chapters on the development languages. In addition to the basics, application-related implementation options and examples, as well as a focus on individual elements of the programming language (so-called "re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
FLWOR
The programming language XQuery defines FLWOR (pronounced 'flower') as an expression that supports iteration and binding of variables to intermediate results. FLWOR is an acronym: FOR, LET, WHERE, ORDER BY, RETURN. FLWOR is loosely analogous to SQL's SELECT-FROM-WHERE and can be used to provide join-like functionality to XML Extensible Markup Language (XML) is a markup language and file format for storing, transmitting, and reconstructing arbitrary data. It defines a set of rules for encoding documents in a format that is both human-readable and machine-readable. T ... documents. *''for'' creates a sequence of nodes *''let'' binds a sequence to a variable *''where'' filters the nodes on a boolean expression *''order by'' sorts the nodes *''return'' gets evaluated once for every node Example for $d in doc("depts.xml")//deptno let $e := doc("emps.xml")//employee eptno = $d where count($e) >= 10 order by avg($e/salary) descending return ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glasgow Haskell Compiler
The Glasgow Haskell Compiler (GHC) is an open-source native code compiler for the functional programming language Haskell. It provides a cross-platform environment for the writing and testing of Haskell code and it supports numerous extensions, libraries, and optimisations that streamline the process of generating and executing code. GHC is the most commonly used Haskell compiler. The lead developers are Simon Peyton Jones and Simon Marlow. History GHC originally started in 1989 as a prototype, written in LML (Lazy ML) by Kevin Hammond at the University of Glasgow. Later that year, the prototype was completely rewritten in Haskell, except for its parser, by Cordelia Hall, Will Partain, and Simon Peyton Jones. Its first beta release was on 1 April 1991 and subsequent releases added a strictness analyzer as well as language extensions such as monadic I/O, mutable arrays, unboxed data types, concurrent and parallel programming models (such as software transactional memory and dat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Associative Array
In computer science, an associative array, map, symbol table, or dictionary is an abstract data type that stores a collection of (key, value) pairs, such that each possible key appears at most once in the collection. In mathematical terms an associative array is a function with ''finite'' domain. It supports 'lookup', 'remove', and 'insert' operations. The dictionary problem is the classic problem of designing efficient data structures that implement associative arrays. The two major solutions to the dictionary problem are hash tables and search trees..Dietzfelbinger, M., Karlin, A., Mehlhorn, K., Meyer auf der Heide, F., Rohnert, H., and Tarjan, R. E. 1994"Dynamic Perfect Hashing: Upper and Lower Bounds". SIAM J. Comput. 23, 4 (Aug. 1994), 738-761. http://portal.acm.org/citation.cfm?id=182370 In some cases it is also possible to solve the problem using directly addressed arrays, binary search trees, or other more specialized structures. Many programming languages include ass ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Racket (programming Language)
Racket is a general-purpose, multi-paradigm programming language and a multi-platform distribution that includes the Racket language, compiler, large standard library, IDE, development tools, and a set of additional languages including Typed Racket (a sister language of Racket with a static type-checker), Swindle, FrTime, Lazy Racket, R5RS & R6RS Scheme, Scribble, Datalog, Racklog, Algol 60 and several teaching languages. The Racket language is a modern dialect of Lisp and a descendant of Scheme. It is designed as a platform for programming language design and implementation. In addition to the core Racket language, ''Racket'' is also used to refer to the family of programming languages and set of tools supporting development on and with Racket. Racket is also used for scripting, computer science education, and research. The Racket platform provides an implementation of the Racket language (including a runtime system, libraries, and compiler supporting several compilation m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Set (computer Science)
In computer science, a set is an abstract data type that can store unique values, without any particular order. It is a computer implementation of the mathematical concept of a finite set. Unlike most other collection types, rather than retrieving a specific element from a set, one typically tests a value for membership in a set. Some set data structures are designed for static or frozen sets that do not change after they are constructed. Static sets allow only query operations on their elements — such as checking whether a given value is in the set, or enumerating the values in some arbitrary order. Other variants, called dynamic or mutable sets, allow also the insertion and deletion of elements from the set. A multiset is a special kind of set in which an element can appear multiple times in the set. Type theory In type theory, sets are generally identified with their indicator function (characteristic function): accordingly, a set of values of type A may be denoted by 2^ o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monads In Functional Programming
In functional programming, a monad is a software design pattern with a structure that combines program fragments ( functions) and wraps their return values in a type with additional computation. In addition to defining a wrapping monadic type, monads define two operators: one to wrap a value in the monad type, and another to compose together functions that output values of the monad type (these are known as monadic functions). General-purpose languages use monads to reduce boilerplate code needed for common operations (such as dealing with undefined values or fallible functions, or encapsulating bookkeeping code). Functional languages use monads to turn complicated sequences of functions into succinct pipelines that abstract away control flow, and side-effects. Both the concept of a monad and the term originally come from category theory, where a monad is defined as a functor with additional structure. Research beginning in the late 1980s and early 1990s established that monads ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heinrich Kleisli
Heinrich Kleisli (; October 19, 1930 – April 5, 2011) was a Swiss mathematician. He is the namesake of several constructions in category theory, including the Kleisli category and Kleisli triples. He is also the namesake of the Kleisli Query System, a tool for integration of heterogeneous databases developed at the University of Pennsylvania. Kleisli earned his Ph.D. at ETH Zurich in 1960, having been supervised by Beno Eckmann and Ernst Specker. His dissertation was on homotopy and abelian categories. He served as an associate professor at the University of Ottawa before relocating to the University of Fribourg The University of Fribourg (french: Université de Fribourg; german: Universität Freiburg) is a public university located in Fribourg, Switzerland. The roots of the university can be traced back to 1580, when the notable Jesuit Peter Canisi ... in 1966. He became a full professor at Fribourg in 1967. External links * In memoriam: Prof. emerit. Heinri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Haskell Programming Language
Haskell () is a general-purpose, statically-typed, purely functional programming language with type inference and lazy evaluation. Designed for teaching, research and industrial applications, Haskell has pioneered a number of programming language features such as type classes, which enable type-safe operator overloading, and monadic IO. Haskell's main implementation is the Glasgow Haskell Compiler (GHC). It is named after logician Haskell Curry. Haskell's semantics are historically based on those of the Miranda programming language, which served to focus the efforts of the initial Haskell working group. The last formal specification of the language was made in July 2010, while the development of GHC continues to expand Haskell via language extensions. Haskell is used in academia and industry. , Haskell was the 28th most popular programming language by Google searches for tutorials, and made up less than 1% of active users on the GitHub source code repository. History ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Miranda Programming Language
Miranda is a lazy, purely functional programming language designed by David Turner as a successor to his earlier programming languages SASL and KRC, using some concepts from ML and Hope. It was produced by Research Software Ltd. of England (which holds a trademark on the name ''Miranda'') and was the first purely functional language to be commercially supported. Miranda was first released in 1985 as a fast interpreter in C for Unix-flavour operating systems, with subsequent releases in 1987 and 1989. It had a strong influence on the later Haskell programming language. In 2020 a version of Miranda was released as open source under a BSD licence. The codebase has been updated to conform to modern C standards (C11/ C18) and to generate 64-bit binaries. This has been tested on operating systems including Debian, Ubuntu, WSL/Ubuntu, and MacOS ( Catalina). Overview Miranda is a lazy, purely functional programming language. That is, it lacks side effects and imperative pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
