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SECD Machine
The SECD machine is a highly influential (see: '' Landin's contribution'') virtual machine and abstract machine intended as a target for compilers of functional programming languages. The letters stand for stack, environment, control, dump, respectively, which are the internal registers of the machine. The registers stack, control, and dump point to (some realizations of) stacks, and environment points to (some realization of) an associative array. The machine was the first to be specifically designed to evaluate lambda calculus expressions. It was originally described by Peter 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 o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peter Landin
Peter John Landin (5 June 1930 – 3 June 2009) was a British computer scientist. He was one of the first to realise that the lambda calculus could be used to model a programming language, an insight that is essential to the development of both functional programming and denotational semantics. Academic Landin was born in Sheffield, where he attended King Edward VII School; he graduated from Clare College, Cambridge. From 1960 to 1964, he was the assistant to Christopher Strachey when the latter was an independent computer consultant in London. Most of his work was published during this period and the brief time he worked for Univac and at the Massachusetts Institute of Technology in the United States, before taking a position at Queen Mary University of London. During the 1970s and 1980s, his efforts went into building the computer science department in Queen Mary College, developing courses, and teaching students, as set forth in the foreword to the textbook ''Programming fro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stack (abstract Data Type)
In computer science, a stack is an abstract data type that serves as a collection (abstract data type), collection of elements with two main operations: * Push, which adds an element to the collection, and * Pop, which removes the most recently added element. Additionally, a peek (data type operation), peek operation can, without modifying the stack, return the value of the last element added. The name ''stack'' is an analogy to a set of physical items stacked one atop another, such as a stack of plates. The order in which an element added to or removed from a stack is described as last in, first out, referred to by the acronym LIFO. As with a stack of physical objects, this structure makes it easy to take an item off the top of the stack, but accessing a Data, datum deeper in the stack may require removing multiple other items first. Considered a sequential collection, a stack has one end which is the only position at which the push and pop operations may occur, the ''top'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apply
In mathematics and computer science, apply is a function that applies a function to arguments. It is central to programming languages derived from lambda calculus, such as LISP and Scheme, and also in functional languages. It has a role in the study of the denotational semantics of computer programs, because it is a continuous function on complete partial orders. Apply is also a continuous function in homotopy theory, and, indeed underpins the entire theory: it allows a homotopy deformation to be viewed as a continuous path in the space of functions. Likewise, valid mutations (refactorings) of computer programs can be seen as those that are "continuous" in the Scott topology. The most general setting for apply is in category theory, where it is right adjoint to currying in closed monoidal categories. A special case of this are the Cartesian closed categories, whose internal language is simply typed lambda calculus. Programming In computer programming, apply applies a fu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reverse Polish Notation
Reverse Polish notation (RPN), also known as reverse Łukasiewicz notation, Polish postfix notation or simply postfix notation, is a mathematical notation in which operators ''follow'' their operands, in contrast to prefix or Polish notation (PN), in which operators ''precede'' their operands. The notation does not need any parentheses for as long as each operator has a fixed number of operands. The term ''postfix notation'' describes the general scheme in mathematics and computer sciences, whereas the term ''reverse Polish notation'' typically refers specifically to the method used to enter calculations into hardware or software calculators, which often have additional side effects and implications depending on the actual implementation involving a stack. The description "Polish" refers to the nationality of logician Jan Łukasiewicz, who invented Polish notation in 1924. The first computer to use postfix notation, though it long remained essentially unknown outside of G ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Closure (computer Programming)
In programming languages, a closure, also lexical closure or function closure, is a technique for implementing lexically scoped name binding in a language with first-class functions. Operationally, a closure is a record storing a function together with an environment. The environment is a mapping associating each free variable of the function (variables that are used locally, but defined in an enclosing scope) with the value or reference to which the name was bound when the closure was created. Unlike a plain function, a closure allows the function to access those ''captured variables'' through the closure's copies of their values or references, even when the function is invoked outside their scope. History and etymology The concept of closures was developed in the 1960s for the mechanical evaluation of expressions in the λ-calculus and was first fully implemented in 1970 as a language feature in the PAL programming language to support lexically scoped first-class functio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ALGOL 60
ALGOL 60 (short for ''Algorithmic Language 1960'') is a member of the ALGOL family of computer programming languages. It followed on from ALGOL 58 which had introduced code blocks and the begin and end pairs for delimiting them, representing a key advance in the rise of structured programming. ALGOL 60 was one of the first languages implementing function definitions (that could be invoked recursively). ALGOL 60 function definitions could be nested within one another (which was first introduced by any programming language), with lexical scope. It gave rise to many other languages, including CPL, PL/I, Simula, BCPL, B, Pascal, and C. Practically every computer of the era had a systems programming language based on ALGOL 60 concepts. Niklaus Wirth based his own ALGOL W on ALGOL 60 before moving to develop Pascal. Algol-W was intended to be the next generation ALGOL but the ALGOL 68 committee decided on a design that was more complex and advanced rather than a cleaned ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
David Turner (computer Scientist)
David A. Turner (26 January 1946 – 19 October 2023) was 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). Turner's work on Miranda had a strong influence on the later Haskell. Turner first implemented SASL using the abstract SECD machine, but then reimplemented them in 1978 using SKI combinator calculus. This approach was used by Thomas Johnsson and Lennart Augustsson in the design of the g-machine that evolved to become the standard mechanism for lazy evaluation in call-by-need languages. In 1981, Turner received the Doctor of Philosophy (D.Phil.) from the University of Oxford, for his dissertation "Aspects of the Implementation of Programming Languages: The Compilation of an Applicative La ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High-level Language Computer Architecture
A high-level language computer architecture (HLLCA) is a computer architecture designed to be targeted by a specific high-level programming language (HLL), rather than the architecture being dictated by hardware considerations. It is accordingly also termed language-directed computer design, coined in and primarily used in the 1960s and 1970s. HLLCAs were popular in the 1960s and 1970s, but largely disappeared in the 1980s. This followed the dramatic failure of the Intel 432 (1981) and the emergence of optimizing compilers and reduced instruction set computer (RISC) architectures and RISC-like complex instruction set computer (CISC) architectures, and the later development of just-in-time compilation (JIT) for HLLs. A detailed survey and critique can be found in . HLLCAs date almost to the beginning of HLLs, in the Burroughs large systems (1961), which were designed for ALGOL 60 (1960), one of the first HLLs. The best known HLLCAs may be the Lisp machines of the 1970s and 1980s, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
University Of Calgary
{{Infobox university , name = University of Calgary , image = University of Calgary coat of arms without motto scroll.svg , image_size = 150px , caption = Coat of arms , former_name = Normal School (1905–1913)Calgary Normal School (1913–1945)Calgary Branch of the Faculty of Education of the University of Alberta (1945–1958)University of Alberta in Calgary (1958–1966){{efn, The following are names of the predecessor institution which the University of Calgary originates from, prior to its reorganization as a standalone university. , motto = {{Lang, gd, Mo Shùile Togam Suas (Canadian Gaelic, Gaelic) , mottoeng = I will lift up my eyes , established = {{Start date and age, 1966, 04, 26, df=yes, p=yes, br=yes , type = Public university, Public , endowment = {{CAD, 1.176 billion (2023) , chancellor = J ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer History Museum
The Computer History Museum (CHM) is a computer museum in Mountain View, California. The museum presents stories and artifacts of Silicon Valley and the Information Age, and explores the Digital Revolution, computing revolution and its impact on society. History The museum's origins date to 1968 when Gordon Bell began a quest for a historical collection and, at that same time, others were looking to preserve the Whirlwind (computer), Whirlwind computer. The resulting ''Museum Project'' had its first exhibit in 1975, located in a converted coat closet in a Digital Equipment Corporation, DEC lobby. In 1978, the museum, now ''The Digital Computer Museum'' (TDCM), moved to a larger DEC lobby in Marlborough, Massachusetts and opened to the public in September 1979. Maurice Wilkes presented the first lecture at TDCM in 1979 – the presentation of such lectures has continued to the present time. TDCM incorporated as ''The Computer Museum, Boston, The Computer Museum'' (TCM) in 1982. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Operational Semantics
Operational semantics is a category of formal programming language semantics in which certain desired properties of a program, such as correctness, safety or security, are verified by constructing proofs from logical statements about its execution and procedures, rather than by attaching mathematical meanings to its terms (denotational semantics). Operational semantics are classified in two categories: structural operational semantics (or small-step semantics) formally describe how the ''individual steps'' of a computation take place in a computer-based system; by opposition natural semantics (or big-step semantics) describe how the ''overall results'' of the executions are obtained. Other approaches to providing a formal semantics of programming languages include axiomatic semantics and denotational semantics. The operational semantics for a programming language describes how a valid program is interpreted as sequences of computational steps. These sequences then ''are'' the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
