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Fexpr
In Lisp programming languages, a fexpr is a function whose operands are passed to it without being evaluated. When a fexpr is called, only the body of the fexpr is evaluated; no other evaluations take place except when explicitly initiated by the fexpr. In contrast, when an ordinary Lisp function is called, the operands are evaluated automatically, and only the results of these evaluations are provided to the function; and when a (traditional) Lisp macro is called, the operands are passed in unevaluated, but whatever result the macro function returns is automatically evaluated. Origin of the name "fexpr" In early Lisp, the environment mapped each symbol to an association list, rather than directly to a value.McCarthy et al., ''Lisp I Programmer's Manual'', pp. 88–91. Standard keys for these lists included two keys used to store a data value, to be looked up when the symbol occurred as an argument ( and ); and four keys used to store a function, to be looked up when the symbol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macro (computer Science)
In computer programming, a macro (short for "macro instruction"; ) is a rule or pattern that specifies how a certain input should be mapped to a replacement output. Applying a macro to an input is known as macro expansion. The input and output may be a sequence of lexical tokens or characters, or a syntax tree. Character macros are supported in software applications to make it easy to invoke common command sequences. Token and tree macros are supported in some programming languages to enable code reuse or to extend the language, sometimes for domain-specific languages. Macros are used to make a sequence of computing instructions available to the programmer as a single program statement, making the programming task less tedious and less error-prone. Thus, they are called "macros" because a "big" block of code can be expanded from a "small" sequence of characters. Macros often allow positional or keyword parameters that dictate what the conditional assembler program gen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ECL Programming Language
The ECL programming language and system were an extensible high-level programming language and development environment developed at Harvard University in the 1970s. The name 'ECL' stood for 'Extensible Computer Language' or 'EClectic Language'. Some publications used the name 'ECL' for the system as a whole and EL/1 (Extensible Language) for the language. ECL was an interactive system where programs were represented within the system; there was a compatible compiler and interpreter. It had an ALGOL-like syntax and an extensible data type system, with data types as first-class citizens. Data objects were values, not references, and the calling conventions gave a choice between call by value and call by reference for each argument. ECL was primarily used for research and teaching in programming language design, programming methodology (in particular programming by transformational refinement), and programming environments at Harvard, though it was said to be used at some govern ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lisp (programming Language)
Lisp (historically LISP, an abbreviation of "list processing") is a family of programming languages with a long history and a distinctive, fully parenthesized prefix notation. Originally specified in the late 1950s, it is the second-oldest high-level programming language still in common use, after Fortran. Lisp has changed since its early days, and many dialects have existed over its history. Today, the best-known general-purpose Lisp dialects are Common Lisp, Scheme, Racket, and Clojure. Lisp was originally created as a practical mathematical notation for computer programs, influenced by (though not originally derived from) the notation of Alonzo Church's lambda calculus. It quickly became a favored programming language for artificial intelligence (AI) research. As one of the earliest programming languages, Lisp pioneered many ideas in computer science, including tree data structures, automatic storage management, dynamic typing, conditionals, higher-order function ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abstract Syntax Tree
An abstract syntax tree (AST) is a data structure used in computer science to represent the structure of a program or code snippet. It is a tree representation of the abstract syntactic structure of text (often source code) written in a formal language. Each node of the tree denotes a construct occurring in the text. It is sometimes called just a syntax tree. The syntax is "abstract" in the sense that it does not represent every detail appearing in the real syntax, but rather just the structural or content-related details. For instance, grouping parentheses are implicit in the tree structure, so these do not have to be represented as separate nodes. Likewise, a syntactic construct like an if-condition-then statement may be denoted by means of a single node with three branches. This distinguishes abstract syntax trees from concrete syntax trees, traditionally designated parse trees. Parse trees are typically built by a parser during the source code translation and compiling pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DWIM
DWIM (do what I mean) computer systems attempt to anticipate what users intend to do, correcting trivial errors automatically rather than blindly executing users' explicit but potentially incorrect input. Software The term was coined by Warren Teitelman in his DWIM package for BBN Lisp, part of his PILOT system, sometime before 1966.Warren Teitelman, "PILOT: A Step towards Man-Computer Symbiosis", M.I.T. Ph.D. Dissertation, Project MAC MAC-TR-32, September 1966DTIC AD0638446 p. 51Warren Teitelman, "Toward a programming laboratory", in J. N. Buxton and , ''Software Engineering Techniques'', April 1970, a report on a conference sponsored by the NATO Science Committee ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ISWIM
ISWIM (If You See What I Mean) is an abstract computer programming language (or a family of languages) devised by Peter Landin and first described in his article "The Next 700 Programming Languages", published in the ''Communications of the ACM'' in 1966. Although not implemented, it has proved very influential in the development of programming languages, especially functional programming languages such as SASL, Miranda, ML, Haskell and their successors, and dataflow programming languages like Lucid. Design ISWIM is an imperative programming language with a functional core, consisting of a syntactic sugaring of lambda calculus to which are added mutable variables and assignment and a powerful control mechanism: the ''program point'' operator. Being based on lambda calculus, ISWIM has higher-order functions and lexically scoped variables. The operational semantics of ISWIM are defined using Landin's SECD machine and use call-by-value, that is eager evaluation. A goal of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Whole-program Analysis
Interprocedural optimization (IPO) is a collection of compiler techniques used in computer programming to improve performance in programs containing many frequently used functions of small or medium length. IPO differs from other compiler optimizations by analyzing the entire program as opposed to a single function or block of code. IPO seeks to reduce or eliminate duplicate calculations and inefficient use of memory and to simplify iterative sequences such as loops. If a call to another routine occurs within a loop, IPO analysis may determine that it is best to inline that routine. Additionally, IPO may re-order the routines for better memory layout and locality. IPO may also include typical compiler optimizations applied on a whole-program level, for example, dead code elimination (DCE), which removes code that is never executed. IPO also tries to ensure better use of constants. Modern compilers offer IPO as an option at compile-time. The actual IPO process may occur at any st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theory (mathematical Logic)
In mathematical logic, a theory (also called a formal theory) is a set of sentences in a formal language. In most scenarios a deductive system is first understood from context, giving rise to a formal system that combines the language with deduction rules. An element \phi\in T of a deductively closed theory T is then called a theorem of the theory. In many deductive systems there is usually a subset \Sigma \subseteq T that is called "the set of axioms" of the theory T, in which case the deductive system is also called an " axiomatic system". By definition, every axiom is automatically a theorem. A first-order theory is a set of first-order sentences (theorems) recursively obtained by the inference rules of the system applied to the set of axioms. General theories (as expressed in formal language) When defining theories for foundational purposes, additional care must be taken, as normal set-theoretic language may not be appropriate. The construction of a theory begins ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Formal System
A formal system is an abstract structure and formalization of an axiomatic system used for deducing, using rules of inference, theorems from axioms. In 1921, David Hilbert proposed to use formal systems as the foundation of knowledge in mathematics. The term ''formalism'' is sometimes a rough synonym for ''formal system'', but it also refers to a given style of notation, for example, Paul Dirac's bra–ket notation. Concepts A formal system has the following: * Formal language, which is a set of well-formed formulas, which are strings of symbols from an alphabet, formed by a formal grammar (consisting of production rules or formation rules). * Deductive system, deductive apparatus, or proof system, which has rules of inference that take axioms and infers theorems, both of which are part of the formal language. A formal system is said to be recursive (i.e. effective) or recursively enumerable if the set of axioms and the set of inference rules are decidable ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lambda Calculus
In mathematical logic, the lambda calculus (also written as ''λ''-calculus) is a formal system for expressing computability, computation based on function Abstraction (computer science), abstraction and function application, application using variable Name binding, binding and Substitution (algebra), substitution. Untyped lambda calculus, the topic of this article, is a universal machine, a model of computation that can be used to simulate any Turing machine (and vice versa). It was introduced by the mathematician Alonzo Church in the 1930s as part of his research into the foundations of mathematics. In 1936, Church found a formulation which was #History, logically consistent, and documented it in 1940. Lambda calculus consists of constructing #Lambda terms, lambda terms and performing #Reduction, reduction operations on them. A term is defined as any valid lambda calculus expression. In the simplest form of lambda calculus, terms are built using only the following rules: # x: A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mitchell Wand
Mitchell Wand is a computer science professor at Northeastern University. He received his Ph.D. from Massachusetts Institute of Technology The Massachusetts Institute of Technology (MIT) is a Private university, private research university in Cambridge, Massachusetts, United States. Established in 1861, MIT has played a significant role in the development of many areas of moder .... His research has centred on programming languages and he is a member of the Northeastern Programming Research Lab. He is also the co-author, with Daniel P. Friedman and Christopher T. Haynes, of '' Essentials of Programming Languages''. References External links Northeastern University Programming Research Lab HomepageMitchell Wand's Homepage at Northeastern University* American computer scientists Programming language researchers Living people Year of birth missing (living people) {{compu-scientist-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reification (computer Science)
In computer science, reification is the process by which an abstract idea about a computer program, program is turned into an explicit data model or other object created in a programming language. A computable/addressable object—a ''resource''—is created in a system as a proxy for a non computable/addressable object. By means of reification, something that was previously implicit, unexpressed, and possibly inexpressible is explicitly formulated and made available to conceptual (logical or computational) manipulation. Informally, reification is often referred to as "making something a first-class citizen" within the scope of a particular system. Some aspect of a system can be reified at ''language design time'', which is related to Reflection (computer science), reflection in programming languages. It can be applied as a stepwise refinement at ''system design time''. Reification is one of the most frequently used techniques of conceptual analysis and knowledge representation. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
