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List Comprehension
A list comprehension is a syntactic construct available in some programming languages for creating a list based on existing lists. It follows the form of the mathematical '' set-builder notation'' (''set comprehension'') as distinct from the use of map and filter functions. Overview Consider the following example in mathematical 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 words, the set of all even numbers greater than 2. In this annotated version of the example: :S=\ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Syntax Of Programming Languages
In computer science, the syntax of a computer language is the rules that define the combinations of symbols that are considered to be correctly structured statements or 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 computer languages are based on sequences of 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 strings, before trying to figure out the general rules from these examples. Syntax therefore refers to the ''form'' of the code, and is contrasted with semantics – the ''meaning''. In processing co ... [...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] |
Glasgow Haskell Compiler
The Glasgow Haskell Compiler (GHC) is a native or machine code compiler for the functional programming language Haskell. It provides a cross-platform software environment for writing and testing Haskell code and supports many extensions, libraries, and optimisations that streamline the process of generating and executing code. GHC is the most commonly used Haskell compiler. It is free and open-source software released under a BSD license. History GHC originally begun in 1989 as a prototype, written in Lazy ML (LML) 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. Later releases added a strictness analyzer and language extensions such as monadic I/O, mutable arrays, unboxed data types, concurrent and parallel programming models (such as software transactional memory and data parallelism) and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Associative Array
In computer science, an associative array, key-value store, 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 It is sometimes also possible to solve the problem using directly addressed arrays, binary search trees, or other more specialized structures. Many programmin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Racket (programming Language)
Racket is a General-purpose programming language, general-purpose, multi-paradigm programming language. The Racket language is a modern dialect of Lisp (programming language), Lisp and a descendant of Scheme (programming language), Scheme. It is designed as a platform for programming language theory, 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 script (computing), 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 modes: machine code, machine-independent, interpreted, and JIT) along with the DrRacket integrated development environment (IDE) written in Racket. Racket is used by the ProgramByDesign outreach program, which aims to tur ... [...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 sequence, order. It is a computer implementation of the mathematics, mathematical concept of a finite set. Unlike most other collection (abstract data type), 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): accord ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Python (programming Language)
Python is a high-level programming language, high-level, general-purpose programming language. Its design philosophy emphasizes code readability with the use of significant indentation. Python is type system#DYNAMIC, dynamically type-checked and garbage collection (computer science), garbage-collected. It supports multiple programming paradigms, including structured programming, structured (particularly procedural programming, procedural), object-oriented and functional programming. It is often described as a "batteries included" language due to its comprehensive standard library. Guido van Rossum began working on Python in the late 1980s as a successor to the ABC (programming language), ABC programming language, and he first released it in 1991 as Python 0.9.0. Python 2.0 was released in 2000. Python 3.0, released in 2008, was a major revision not completely backward-compatible with earlier versions. Python 2.7.18, released in 2020, was the last release of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monads In Functional Programming
In functional programming, monads are a way to structure computations as a sequence of steps, where each step not only produces a value but also some extra information about the computation, such as a potential failure, non-determinism, or side effect. More formally, a monad is a type constructor M equipped with two operations, which lifts a value into the monadic context, and which chains monadic computations. In simpler terms, monads can be thought of as interfaces implemented on type constructors, that allow for functions to abstract over various type constructor variants that implement monad (e.g. , , etc.). Both the concept of a monad and the term originally come from category theory, where a monad is defined as an endofunctor with additional structure. Research beginning in the late 1980s and early 1990s established that monads could bring seemingly disparate computer-science problems under a unified, functional model. Category theory also provides a few formal requiremen ... [...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 (; ) is a public university located in Fribourg, Switzerland. The roots of the university can be traced back to 1580, when the notable Jesuit Peter Canisius founded the Collège Saint-Michel in the City of Fribourg ... in 1966. He became a full professor at Fribourg in 1967. Selected publications * Kleisli, H.''Every standard ... [...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 pioneered several programming language features such as type classes, which enable type-safe operator overloading, and monadic input/output (IO). It is named after logician Haskell Curry. Haskell's main implementation is the Glasgow Haskell Compiler (GHC). 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. H ... [...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 language. Turner stated that the benefits of Miranda over Haskell are: "Smaller language, simpler type system, simpler arithmetic". In 2020 a version of Miranda was released as open source under a BSD licence. The code 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). Name The na ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Philip Wadler
Philip Lee Wadler (born April 8, 1956) is a UK-based American computer scientist known for his contributions to programming language design and type theory. He holds the position of Personal Chair of theoretical computer science at the Laboratory for Foundations of Computer Science at the School of Informatics, University of Edinburgh. He has contributed to the theory behind functional programming and the use of monads; and the designs of the purely functional language Haskell and the XQuery declarative query language. In 1984, he created the Orwell language. Wadler was involved in adding generic types to Java 5.0. He is also author of "Theorems for free!", a paper that gave rise to much research on functional language optimization (see also Parametricity). Education Wadler received a Bachelor of Science degree in mathematics from Stanford University in 1977, and a Master of Science degree in computer science from Carnegie Mellon University in 1979. He completed his Doctor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
