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Graph Reduction
In computer science, graph reduction implements an efficient version of non-strict evaluation, an evaluation strategy where the arguments to a function are not immediately evaluated. This form of non-strict evaluation is also known as lazy evaluation and used in functional programming languages. The technique was first developed by Chris Wadsworth in 1971. Motivation A simple example of evaluating an arithmetic expression follows: : \begin & & &((2+2)+(2+2))+(3+3) \\ & &=&((2+2)+(2+2))+ 6 \\ & &=&((2+2)+ 4)+6 \\ & &=&(4+4)+6 \\ & &=&8+6 \\ & &=&14 \end The above reduction sequence employs a strategy known as outermost tree reduction. The same expression can be evaluated using innermost tree reduction, yielding the reduction sequence: : \begin & & &((2+2)+(2+2))+(3+3) \\ & &= &((2+2)+4)+(3+3) \\ & &= &(4+4)+(3+3) \\ & &= &(4+4)+6 \\ & &= &8+6 \\ & &= &14 \end Notice that the reduction order is made explicit by the addition of parentheses. This expression could ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Science
Computer science is the study of computation, automation, and information. Computer science spans theoretical disciplines (such as algorithms, theory of computation, information theory, and automation) to Applied science, practical disciplines (including the design and implementation of Computer architecture, hardware and Computer programming, software). Computer science is generally considered an area of research, academic research and distinct from computer programming. Algorithms and data structures are central to computer science. The theory of computation concerns abstract models of computation and general classes of computational problem, problems that can be solved using them. The fields of cryptography and computer security involve studying the means for secure communication and for preventing Vulnerability (computing), security vulnerabilities. Computer graphics (computer science), Computer graphics and computational geometry address the generation of images. Progr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eager Evaluation
In a programming language, an evaluation strategy is a set of rules for evaluating expressions. The term is often used to refer to the more specific notion of a ''parameter-passing strategy'' that defines the kind of value that is passed to the function for each parameter (the ''binding strategy'') and whether to evaluate the parameters of a function call, and if so in what order (the ''evaluation order''). The notion of reduction strategy is distinct, although some authors conflate the two terms and the definition of each term is not widely agreed upon. To illustrate, executing a function call f(a,b) may first evaluate the arguments a and b, store the results in references or memory locations ref_a and ref_b, then evaluate the function's body with those references passed in. This gives the function the ability to look up the argument values, to modify them via assignment as if they were local variables, and to return values via the references. This is the call-by-reference evalu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Implementation Of Functional Programming Languages
Implementation is the realization of an application, or execution of a plan, idea, model, design, specification, standard, algorithm, or policy. Industry-specific definitions Computer science In computer science, an implementation is a realization of a technical specification or algorithm as a program, software component, or other computer system through computer programming and deployment. Many implementations may exist for a given specification or standard. For example, web browsers contain implementations of World Wide Web Consortium-recommended specifications, and software development tools contain implementations of programming languages. A special case occurs in object-oriented programming, when a concrete class implements an interface; in this case the concrete class is an ''implementation'' of the interface and it includes methods which are ''implementations'' of those methods specified by the interface. Information technology In the information technology during ind ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SECD Machine
The SECD machine is a highly influential (''see: '') virtual machine and abstract machine intended as a target for functional programming language compilers. The letters stand for Stack, Environment, Control, Dump—the internal registers of the machine. The registers Stack, Control, and Dump point to (some realisations of) stacks, and Environment points to (some realisation of) an associative array. The machine was the first to be specifically designed to evaluate lambda calculus expressions. It was originally described by Peter J. Landin in "The Mechanical Evaluation of Expressions" in 1964. The description published by Landin was fairly abstract, and left many implementation choices open (like an operational semantics). Lispkit Lisp was an influential compiler based on the SECD machine, and the SECD machine has been used as the target for other systems such as Lisp/370. In 1989 researchers at the University of Calgary worked on a hardware implementation of the machine.A pape ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Graph Reduction Machine
A graph reduction machine is a special-purpose computer built to perform combinator calculations by graph reduction. Examples include the SKIM ("S-K-I machine") computer, built at the University of Cambridge Computer Laboratory, and the multiprocessor GRIP ("Graph Reduction In Parallel") computer, built at University College London. See also *SECD machine The SECD machine is a highly influential (''see: '') virtual machine and abstract machine intended as a target for functional programming language compilers. The letters stand for Stack, Environment, Control, Dump—the internal registers of the mac ... References *T. J. W. Clarke, P. Gladstone, C. MacLean, A. C. Norman: ''SKIM — The S, K, I Reduction Machine''. LISP Conference, 1980: 128–135 External linksReduction Machines Parallel Functional Programming: An Introduction, Kevin Hammond Applicative computing systems Functional programming University of Cambridge Computer Laboratory {{Compu-hardware-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SASL Programming Language
SASL (from St Andrews Static Language, alternatively St Andrews Standard Language) is a purely functional programming language developed by David Turner at the University of St Andrews in 1972, based on the applicative subset of ISWIM. In 1976 Turner redesigned and reimplemented it as a non-strict (lazy) language. In this form it was the foundation of Turner's later languages KRC and Miranda, but SASL appears to be untyped whereas Miranda has polymorphic types. Burroughs Corporation The Burroughs Corporation was a major American manufacturer of business equipment. The company was founded in 1886 as the American Arithmometer Company. In 1986, it merged with Sperry UNIVAC to form Unisys. The company's history paralleled many ... used SASL to write a compiler and operating system. Notes External links The SASL Language Manual References * * Academic programming languages Functional languages History of computing in the United Kingdom {{compu-lang-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
David Turner (computer Scientist)
David A. Turner (born 26 January 1946) is a British computer scientist. He is best known for designing and implementing three programming languages, including the first for functional programming based on lazy evaluation, combinator graph reduction, and polymorphic types: SASL (1972), Kent Recursive Calculator (KRC) (1981), and the commercially supported Miranda (1985). Miranda had a strong influence on the later Haskell. He has a Doctor of Philosophy (D.Phil.) from the University of Oxford. He has held professorships at Queen Mary College, London, University of Texas at Austin and the University of Kent at Canterbury, where he has spent most of his career and retains the title of Emeritus Professor of Computation. He was involved with developing international standards in programming and informatics, as a member of the International Federation for Information Processing (IFIP) IFIP Working Group 2.1 on Algorithmic Languages and Calculi, which specified, maintains, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Association For Computing Machinery
The Association for Computing Machinery (ACM) is a US-based international learned society for computing. It was founded in 1947 and is the world's largest scientific and educational computing society. The ACM is a non-profit professional membership group, claiming nearly 110,000 student and professional members . Its headquarters are in New York City. The ACM is an umbrella organization for academic and scholarly interests in computer science ( informatics). Its motto is "Advancing Computing as a Science & Profession". History In 1947, a notice was sent to various people: On January 10, 1947, at the Symposium on Large-Scale Digital Calculating Machinery at the Harvard computation Laboratory, Professor Samuel H. Caldwell of Massachusetts Institute of Technology spoke of the need for an association of those interested in computing machinery, and of the need for communication between them. ..After making some inquiries during May and June, we believe there is ample interest to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Data Structure
In computer science, a data structure is a data organization, management, and storage format that is usually chosen for efficient access to data. More precisely, a data structure is a collection of data values, the relationships among them, and the functions or operations that can be applied to the data, i.e., it is an algebraic structure about data. Usage Data structures serve as the basis for abstract data types (ADT). The ADT defines the logical form of the data type. The data structure implements the physical form of the data type. Different types of data structures are suited to different kinds of applications, and some are highly specialized to specific tasks. For example, relational databases commonly use B-tree indexes for data retrieval, while compiler implementations usually use hash tables to look up identifiers. Data structures provide a means to manage large amounts of data efficiently for uses such as large databases and internet indexing services. Usually, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Directed Graph
In mathematics, and more specifically in graph theory, a directed graph (or digraph) is a graph that is made up of a set of vertices connected by directed edges, often called arcs. Definition In formal terms, a directed graph is an ordered pair where * ''V'' is a set whose elements are called '' vertices'', ''nodes'', or ''points''; * ''A'' is a set of ordered pairs of vertices, called ''arcs'', ''directed edges'' (sometimes simply ''edges'' with the corresponding set named ''E'' instead of ''A''), ''arrows'', or ''directed lines''. It differs from an ordinary or undirected graph, in that the latter is defined in terms of unordered pairs of vertices, which are usually called ''edges'', ''links'' or ''lines''. The aforementioned definition does not allow a directed graph to have multiple arrows with the same source and target nodes, but some authors consider a broader definition that allows directed graphs to have such multiple arcs (namely, they allow the arc set to be a m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Combinator
Combinatory logic is a notation to eliminate the need for quantified variables in mathematical logic. It was introduced by Moses Schönfinkel and Haskell Curry, and has more recently been used in computer science as a theoretical model of computation and also as a basis for the design of functional programming languages. It is based on combinators, which were introduced by Schönfinkel in 1920 with the idea of providing an analogous way to build up functions—and to remove any mention of variables—particularly in predicate logic. A combinator is a higher-order function that uses only function application and earlier defined combinators to define a result from its arguments. In mathematics Combinatory logic was originally intended as a 'pre-logic' that would clarify the role of quantified variables in logic, essentially by eliminating them. Another way of eliminating quantified variables is Quine's predicate functor logic. While the expressive power of combinatory logic t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Expression Graph Reduction
Expression may refer to: Linguistics * Expression (linguistics), a word, phrase, or sentence * Fixed expression, a form of words with a specific meaning * Idiom, a type of fixed expression * Metaphorical expression, a particular word, phrase, or form of words that has a different meaning than its literal form * Expression (sign language), the expressions and postures of the face and body that contribute to the formation of words when signing Symbolic expression * Expression (architecture), implies a clear and authentic displaying of the character or personality of an individual person * Expression (mathematics), a finite combination of symbols that are well-formed according to applicable rules * Expression (computer science), an instruction to execute something that will return a value * Regular expression, a means of matching strings of text in computing * Expression marks, in music, notating the musical dynamics * Symbolic computation expression * S-expression Bodily expres ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
