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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 generates ... [...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 go ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lisp (programming Language)
Lisp (historically LISP) is a family of programming languages with a long history and a distinctive, fully parenthesized prefix notation. Originally specified in 1960, Lisp 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 functions, recursion, the self-hosting compiler, and the read†... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abstract Syntax Tree
In computer science, an abstract syntax tree (AST), or just syntax tree, 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. 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 process. Once built, additional information is added to the AST by means of subsequent processing, e.g., co ... [...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, R ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ISWIM
ISWIM (acronym for 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 go ... [...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 because it analyzes the entire program; other optimizations look at only a single function, or even a single block of code. IPO seeks to reduce or eliminate duplicate calculations, inefficient use of memory, and to simplify iterative sequences such as loops. If there is a call to another routine that occurs within a loop, IPO analysis may determine that it is best to inline that. Additionally, IPO may re-order the routines for better memory layout and locality. IPO may also include typical compiler optimizations on a whole-program level, for example dead code elimination (DCE), which removes code that is never executed. To accomplish this, the compiler tests for branches that are never taken and removes the code in that branch. IP ... [...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, after which 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 by specifying a definite non-empty ''conceptual class'' \mathcal, the element ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Formal System
A formal system is an abstract structure used for inferring theorems from axioms according to a set of rules. These rules, which are used for carrying out the inference of theorems from axioms, are the logical calculus of the formal system. A formal system is essentially an "axiomatic system". In 1921, David Hilbert proposed to use such a system as the foundation for the knowledge in mathematics. A formal system may represent a well-defined abstraction, system of abstract thought. 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. Background Each formal system is described by primitive Symbol (formal), symbols (which collectively form an Alphabet (computer science), alphabet) to finitely construct a formal language from a set of axioms through inferential rules of formation. The system thus consists of valid formulas built up through finite combinations of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lambda Calculus
Lambda calculus (also written as ''λ''-calculus) is a formal system in mathematical logic for expressing computation based on function abstraction and application using variable binding and substitution. It is a universal model of computation that can be used to simulate any Turing machine. It was introduced by the mathematician Alonzo Church in the 1930s as part of his research into the foundations of mathematics. Lambda calculus consists of constructing § lambda terms and performing § reduction operations on them. In the simplest form of lambda calculus, terms are built using only the following rules: * x – variable, a character or string representing a parameter or mathematical/logical value. * (\lambda x.M) – abstraction, function definition (M is a lambda term). The variable x becomes bound in the expression. * (M\ N) – application, applying a function M to an argument N. M and N are lambda terms. The reduction operations include: * (\lambda x.M \rightarrow(\l ... [...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. 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 ''Essentials of Programming Languages'' (''EOPL'') is a textbook on programming languages by Daniel P. Friedman, Mitchell Wand, and Christopher T. Haynes. EOPL surveys the principles of programming languages from an operational perspective. It ...''. 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)
Reification is the process by which an abstract idea about a computer 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 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. Reflective programming languages In the context of programming ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
