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Iterators
In computer programming, an iterator is an object (computing), object that progressively provides access to each item of a Collection (abstract data type), collection, in order. A collection may provide multiple iterators via its Interface (object-oriented programming), interface that provide items in different orders, such as forwards and backwards. An iterator is often implemented in terms of the structure underlying a collection implementation and is often tightly Coupling (computer programming), coupled to the collection to enable the operational semantics of the iterator. An iterator is behaviorally similar to a cursor (databases), database cursor. Iterators date to the CLU (programming language), CLU programming language in 1974. Pattern An iterator provides access to an element of a collection (''element access'') and can change its internal state to provide access to the next element (''element traversal''). It also provides for creation and initialization to a first ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CLU (programming Language)
CLU is a programming language created at the Massachusetts Institute of Technology (MIT) by Barbara Liskov and her students starting in 1973.Liskov, Barbara (1992). "A history of CLU". The second ACM SIGPLAN conference on History of programming languages. While it did not find extensive use, it introduced many features that are used widely now, and is seen as a step in the development of object-oriented programming (OOP). Key contributions include abstract data types, call-by-sharing, iterators, multiple return values (a form of parallel assignment), type-safe parameterized types, and type-safe variant types. It is also notable for its use of classes with constructors and methods, but without inheritance. Clusters The syntax of CLU was based on ALGOL, then the starting point for most new language designs. The key addition was the concept of a ''cluster'', CLU's type extension system and the root of the language's name (CLUster). Clusters correspond generally to the co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coroutine
Coroutines are computer program components that allow execution to be suspended and resumed, generalizing subroutines for cooperative multitasking. Coroutines are well-suited for implementing familiar program components such as cooperative tasks, exceptions, event loops, iterators, infinite lists and pipes. They have been described as "functions whose execution you can pause". Melvin Conway coined the term ''coroutine'' in 1958 when he applied it to the construction of an assembly program. The first published explanation of the coroutine appeared later, in 1963. Definition and types There is no single precise definition of coroutine. In 1980 Christopher D. Marlin summarized two widely-acknowledged fundamental characteristics of a coroutine: # the values of data local to a coroutine persist between successive calls; # the execution of a coroutine is suspended as control leaves it, only to carry on where it left off when control re-enters the coroutine at some later s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Go (programming Language)
Go is a high-level programming language, high-level general purpose programming language that is static typing, statically typed and compiled language, compiled. It is known for the simplicity of its syntax and the efficiency of development that it enables by the inclusion of a large standard library supplying many needs for common projects. It was designed at Google in 2007 by Robert Griesemer, Rob Pike, and Ken Thompson, and publicly announced in November of 2009. It is syntax (programming languages), syntactically similar to C (programming language), C, but also has memory safety, garbage collection (computer science), garbage collection, structural type system, structural typing, and communicating sequential processes, CSP-style concurrency (computer science), concurrency. It is often referred to as Golang to avoid ambiguity and because of its former domain name, golang.org, but its proper name is Go. There are two major implementations: * The original, Self-hosting (compi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Programming
Computer programming or coding is the composition of sequences of instructions, called computer program, programs, that computers can follow to perform tasks. It involves designing and implementing algorithms, step-by-step specifications of procedures, by writing source code, code in one or more programming languages. Programmers typically use high-level programming languages that are more easily intelligible to humans than machine code, which is directly executed by the central processing unit. Proficient programming usually requires expertise in several different subjects, including knowledge of the Domain (software engineering), application domain, details of programming languages and generic code library (computing), libraries, specialized algorithms, and Logic#Formal logic, formal logic. Auxiliary tasks accompanying and related to programming include Requirements analysis, analyzing requirements, Software testing, testing, debugging (investigating and fixing problems), imple ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Object Pascal
Object Pascal is an extension to the programming language Pascal (programming language), Pascal that provides object-oriented programming (OOP) features such as Class (computer programming), classes and Method (computer programming), methods. The language was originally developed by Apple Inc., Apple Computer as ''Clascal'' for the Apple Lisa, Lisa Workshop development system. As Lisa gave way to Mac (computer), Macintosh, Apple collaborated with Niklaus Wirth, the author of Pascal, to develop an officially standardized version of Clascal. This was renamed Object Pascal. Through the mid-1980s, Object Pascal was the main programming language for early versions of the MacApp application framework. The language lost its place as the main development language on the Mac in 1991 with the release of the C++-based MacApp 3.0. Official support ended in 1996. Gen Digital, Symantec also developed a compiler for Object Pascal for their Think Pascal product, which could compile programs muc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Random Access
Random access (also called direct access) is the ability to access an arbitrary element of a sequence in equal time or any datum from a population of addressable elements roughly as easily and efficiently as any other, no matter how many elements may be in the set. In computer science it is typically contrasted to sequential access which requires data to be retrieved in the order it was stored. For example, data might be stored notionally in a single sequence like a row, in two dimensions like rows and columns on a surface, or in multiple dimensions. However, given all the coordinates, a program can access each record about as quickly and easily as any other. In this sense, the choice of datum is arbitrary in the sense that no matter which item is sought, all that is needed to find it is its address, i.e. the coordinates at which it is located, such as its row and column (or its track and record number on a magnetic drum). At first, the term "random access" was used because th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Data-driven Programming
In computer programming, data-driven programming is a programming paradigm in which the program statements describe the data to be matched and the processing required rather than defining a sequence of steps to be taken. Standard examples of data-driven languages are the text-processing languages sed and AWK, and the document transformation language XSLT, where the data is a sequence of lines in an input stream – these are thus also known as line-oriented languages – and pattern matching is primarily done via regular expressions or line numbers. Related paradigms Data-driven programming is similar to event-driven programming, in that both are structured as pattern matching and resulting processing, and are usually implemented by a main loop, though they are typically applied to different domains. The condition/action model is also similar to aspect-oriented programming, where when a join point (condition) is reached, a pointcut (action) is executed. A similar paradigm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Input Stream
In computer science, a stream is a sequence of potentially unlimited data elements made available over time. A stream can be thought of as items on a conveyor belt being processed one at a time rather than in large batches. Streams are processed differently from batch data. Normal functions cannot operate on streams as a whole because they have potentially unlimited data. Formally, streams are '' codata'' (potentially unlimited), not data (which is finite). Functions that operate on a stream producing another stream are known as filters and can be connected in pipelines in a manner analogous to function composition. Filters may operate on one item of a stream at a time or may base an item of output on multiple items of input such as a moving average. Examples The term "stream" is used in a number of similar ways: * "Stream editing", as with sed, awk, and perl. Stream editing processes a file or files, in-place, without having to load the file(s) into a user interface. On ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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] |
Anonymous Function
In computer programming, an anonymous function (function literal, expression or block) is a function definition that is not bound to an identifier. Anonymous functions are often arguments being passed to higher-order functions or used for constructing the result of a higher-order function that needs to return a function. If the function is only used once, or a limited number of times, an anonymous function may be syntactically lighter than using a named function. Anonymous functions are ubiquitous in functional programming languages and other languages with first-class functions, where they fulfil the same role for the function type as literals do for other data types. Anonymous functions originate in the work of Alonzo Church in his invention of the lambda calculus, in which all functions are anonymous, in 1936, before electronic computers. In several programming languages, anonymous functions are introduced using the keyword ''lambda'', and anonymous functions are often ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Foreach
In computer programming, foreach loop (or for-each loop) is a control flow statement for traversing items in a collection. is usually used in place of a standard loop statement. Unlike other loop constructs, however, loops usually maintain no explicit counter: they essentially say "do this to everything in this set", rather than "do this times". This avoids potential off-by-one errors and makes code simpler to read. In object-oriented languages, an iterator, even if implicit, is often used as the means of traversal. The statement in some languages has some defined order, processing each item in the collection from the first to the last. The statement in many other languages, especially array programming languages, does not have any particular order. This simplifies loop optimization in general and in particular allows vector processing of items in the collection concurrently. Syntax Syntax varies among languages. Most use the simple word for, although other use the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intrinsic Function
In computer software, in compiler theory, an intrinsic function, also called built-in function or builtin function, is a function ( subroutine) available for use in a given programming language whose implementation is handled specially by the compiler. Typically, it may substitute a sequence of automatically generated instructions for the original function call, similar to an inline function. Unlike an inline function, the compiler has an intimate knowledge of an intrinsic function and can thus better integrate and optimize it for a given situation. Compilers that implement intrinsic functions may enable them only when a program requests optimization, otherwise falling back to a default implementation provided by the language runtime system (environment). Vectorization and parallelization Intrinsic functions are often used to explicitly implement vectorization and parallelization in languages which do not address such constructs. Some application programming interfaces (API ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
