A programming language is an artificial language that can be used to control the behavior of a machine, particularly a computer. An artificial language is a Language created by a person or a group of people for a certain purpose usually when this purpose is hard to achieve by using a Natural A computer is a Machine that manipulates data according to a list of instructions. ^[1] Programming languages are defined by syntactic and semantic rules which describe their structure and meaning respectively. In Linguistics, syntax (from Ancient Greek grc συν- syn-, "together" and grc τάξις táxis, "arrangement" is the Semantics is the study of meaning in communication The word derives from Greek σημαντικός ( semantikos) "significant" from Many programming languages have some form of written specification of their syntax and semantics; some are defined only by an official implementation.

Programming languages are used to facilitate communication about the task of organizing and manipulating information, and to express algorithms precisely. In Mathematics, Computing, Linguistics and related subjects an algorithm is a sequence of finite instructions often used for Calculation Some authors restrict the term "programming language" to those languages that can express all possible algorithms;^[2] sometimes the term "computer language" is used for more limited artificial languages.

Thousands of different programming languages^[3] have been created, and new languages are created every year.

Definitions

Traits often considered important for constituting a programming language:

• Function: A programming language is a language used to write computer programs, which involve a computer performing some kind of computation^[4] or algorithm and possibly control external devices such as printers, robots,^[5] and so on. Computer programs (also software programs, or just programs) are instructions for a Computer. A computer is a Machine that manipulates data according to a list of instructions. Computation is a general term for any type of Information processing. In Mathematics, Computing, Linguistics and related subjects an algorithm is a sequence of finite instructions often used for Calculation

• Target: Programming languages differ from natural languages in that natural languages are only used for interaction between people, while programming languages also allow humans to communicate instructions to machines. In the Philosophy of language, a natural language (or ordinary language) is a Language that is spoken or written in phonemic-alphabetic or phonemically-related Some programming languages are used by one device to control another. For example PostScript programs are frequently created by another program to control a computer printer or display. PostScript ( PS) is a dynamically typed concatenative Programming language created by John Warnock and Charles Geschke in 1982

• Constructs: Programming languages may contain constructs for defining and manipulating data structures or controlling the flow of execution. A data structure in Computer science is a way of storing Data in a computer so that it can be used efficiently In Computer science control flow (or alternatively flow of control refers to the order in which the individual statements, instructions or Function

• Expressive power: The theory of computation classifies languages by the computations they can express (see Chomsky hierarchy). The theory of computation is the branch of Computer science that deals with whether and how efficiently problems can be solved on a Model of computation, using an Within the field of Computer science, specifically in the area of Formal languages, the Chomsky hierarchy (occasionally referred to as Chomsky–Schützenberger All Turing complete languages can implement the same set of algorithms. In computability theory, several closely-related terms are used to describe the "computational power" of a computational system (such as an Abstract machine or In Mathematics, Computing, Linguistics and related subjects an algorithm is a sequence of finite instructions often used for Calculation ANSI/ISO SQL and Charity are examples of languages that are not Turing complete yet often called programming languages. Charity is a Purely functional experimental Programming language, developed at the University of Calgary. ^[6][7]

Non-computational languages, such as markup languages like HTML or formal grammars like BNF, are usually not considered programming languages. A markup language is an Artificial language using a set of annotations to text that give instructions regarding the structure of text or how it is to be displayed HTML, an initialism of HyperText Markup Language, is the predominant Markup language for Web pages It provides a means to describe the structure In Formal semantics, Computer science and Linguistics, a formal grammar (also called formation rules) is a precise description of a Formal In Computer science, Backus–Naur Form ( BNF) is a Metasyntax used to express Context-free grammars that is a formal way to describe Formal Often a programming language is embedded in the non-computational (host) language.

Purpose

A prominent purpose of programming languages is to provide instructions to a computer. As such, programming languages differ from most other forms of human expression in that they require a greater degree of precision and completeness. When using a natural language to communicate with other people, human authors and speakers can be ambiguous and make small errors, and still expect their intent to be understood. However, computers do exactly what they are told to do, and cannot understand the code the programmer "intended" to write. The combination of the language definition, the program, and the program's inputs must fully specify the external behavior that occurs when the program is executed. Computer programs (also software programs, or just programs) are instructions for a Computer.

Many languages have been designed from scratch, altered to meet new needs, combined with other languages, and eventually fallen into disuse. Although there have been attempts to design one "universal" computer language that serves all purposes, all of them have failed to be accepted in this role. ^[8] The need for diverse computer languages arises from the diversity of contexts in which languages are used:

• Programs range from tiny scripts written by individual hobbyists to huge systems written by hundreds of programmers.
• Programmers range in expertise from novices who need simplicity above all else, to experts who may be comfortable with considerable complexity.
• Programs must balance speed, size, and simplicity on systems ranging from microcontrollers to supercomputers. A microcontroller (also MCU or µC is a functional Computer system-on-a- chip. A supercomputer is a Computer that is at the frontline of processing capacity particularly speed of calculation (at the time of its introduction
• Programs may be written once and not change for generations, or they may undergo nearly constant modification.
• Finally, programmers may simply differ in their tastes: they may be accustomed to discussing problems and expressing them in a particular language.

One common trend in the development of programming languages has been to add more ability to solve problems using a higher level of abstraction. In Computer science, abstraction is a mechanism and practice to reduce and factor out details so that one can focus on a few concepts at a time The earliest programming languages were tied very closely to the underlying hardware of the computer. As new programming languages have developed, features have been added that let programmers express ideas that are more removed from simple translation into underlying hardware instructions. Because programmers are less tied to the needs of the computer, their programs can do more computing with less effort from the programmer. This lets them write more programs in the same amount of time. ^[9]

Natural language processors have been proposed as a way to eliminate the need for a specialized language for programming. Natural language processing ( NLP) is a subfield of Artificial intelligence and Computational linguistics. However, this goal remains distant and its benefits are open to debate. Edsger Dijkstra took the position that the use of a formal language is essential to prevent the introduction of meaningless constructs, and dismissed natural language programming as "foolish. Edsger Wybe Dijkstra ( May 11, 1930 &ndash August 6, 2002; ˈɛtsxər ˈwibə ˈdɛɪkstra was a Dutch computer scientist "^[10] Alan Perlis was similarly dismissive of the idea. Alan Jay Perlis (April 1 1922 &ndash February 7 1990 was an American Computer scientist known for his pioneering work in programming languages and the first recipient ^[11]

Elements

Syntax

Parse tree of Python code with inset tokenization

Syntax highlighting is often used to aid programmers in recognizing elements of source code. A parse tree or concrete syntax tree is an (ordered rooted tree that represents the syntactic structure of a string according to some Syntax highlighting is a feature of some Text editors that displays text&mdashespecially Source code &mdashin different colors and fonts according to The language above is Python. Python is a general-purpose High-level programming language. Its design philosophy emphasizes programmer productivity and code readability

A programming language's surface form is known as its syntax. In Linguistics, syntax (from Ancient Greek grc συν- syn-, "together" and grc τάξις táxis, "arrangement" is the Most programming languages are purely textual; they use sequences of text including words, numbers, and punctuation, much like written natural languages. On the other hand, there are some programming languages which are more graphical in nature, using spatial relationships between symbols to specify a program. A Visual programming language ( VPL) is any Programming language that lets users specify programs by manipulating program

The syntax of a language describes the possible combinations of symbols that form a syntactically correct program. The meaning given to a combination of symbols is handled by semantics. Since most languages are textual, this article discusses textual syntax.

Programming language syntax is usually defined using a combination of regular expressions (for lexical structure) and Backus-Naur Form (for grammatical structure). In Computing, regular expressions provide a concise and flexible means for identifying strings of text of interest such as particular characters words or patterns of characters In Computer science, lexical analysis is the process of converting a sequence of characters into a sequence of tokens In Computer science, Backus–Naur Form ( BNF) is a Metasyntax used to express Context-free grammars that is a formal way to describe Formal In Formal language theory, a context-free grammar ( CFG) is a grammar in which every production rule is of the form V &rarr Below is a simple grammar, based on Lisp:

expression ::= atom | list
atom  ::= number | symbol
number  ::= [+-]?['0'-'9']+
symbol  ::= ['A'-'Z''a'-'z']. Lisp (or LISP) is a family of Computer Programming languages with a long history and a distinctive fully parenthesized syntax *
list  ::= '(' expression* ')'


This grammar specifies the following:

• an expression is either an atom or a list;
• an atom is either a number or a symbol;
• a number is an unbroken sequence of one or more decimal digits, optionally preceded by a plus or minus sign;
• a symbol is a letter followed by zero or more of any characters (excluding whitespace); and
• a list is a matched pair of parentheses, with zero or more expressions inside it.

The following are examples of well-formed token sequences in this grammar: '12345', '()', '(a b c232 (1))'

Not all syntactically correct programs are semantically correct. Many syntactically correct programs are nonetheless ill-formed, per the language's rules; and may (depending on the language specification and the soundness of the implementation) result in an error on translation or execution. In some cases, such programs may exhibit undefined behavior. In Computer science, undefined behavior is a feature of some programming languages &mdash most famously C. Even when a program is well-defined within a language, it may still have a meaning that is not intended by the person who wrote it.

Using natural language as an example, it may not be possible to assign a meaning to a grammatically correct sentence or the sentence may be false:

• "Colorless green ideas sleep furiously. In the Philosophy of language, a natural language (or ordinary language) is a Language that is spoken or written in phonemic-alphabetic or phonemically-related " Colorless green ideas sleep furiously " is a sentence composed by Noam Chomsky in 1957 as an example of a sentence whose Grammar is correct " is grammatically well-formed but has no generally accepted meaning.
• "John is a married bachelor. " is grammatically well-formed but expresses a meaning that cannot be true.

The following C language fragment is syntactically correct, but performs an operation that is not semantically defined (because p is a null pointer, the operations p->real and p->im have no meaning):

complex *p = NULL;
complex abs_p = sqrt (p->real * p->real + p->im * p->im);

The grammar needed to specify a programming language can be classified by its position in the Chomsky hierarchy. Within the field of Computer science, specifically in the area of Formal languages, the Chomsky hierarchy (occasionally referred to as Chomsky–Schützenberger The syntax of most programming languages can be specified using a Type-2 grammar, i. e. , they are context-free grammars. In Formal language theory, a context-free grammar ( CFG) is a grammar in which every production rule is of the form V &rarr ^[12]

Static semantics

The static semantics defines restrictions on the structure of valid texts that are hard or impossible to express in standard syntactic formalisms. ^[13] The most important of these restrictions are covered by type systems.

Type system

For more details on this topic, see Type system. In Computer science, a type system defines how a Programming language classifies values and expressions into '''types''', how it can

For more details on this topic, see Type safety. In Computer science, type safety is a property of some Programming languages that is defined differently by different communities but most definitions involve

A type system defines how a programming language classifies values and expressions into types, how it can manipulate those types and how they interact. This generally includes a description of the data structures that can be constructed in the language. A data structure in Computer science is a way of storing Data in a computer so that it can be used efficiently The design and study of type systems using formal mathematics is known as type theory. In Mathematics, Logic and Computer science, type theory is any of several Formal systems that can serve as alternatives to Naive set theory

Internally, all data in modern digital computers are stored simply as zeros or ones (binary). Debt AIDS Trade in Africa (or DATA) is a Multinational non-government organization founded in January 2002 in London by U2 's The binary numeral system, or base-2 number system, is a Numeral system that represents numeric values using two symbols usually 0 and 1.

Typed versus untyped languages

A language is typed if the specification of every operation defines types of data to which the operation is applicable, with the implication that it is not applicable to other types. ^[14] For example, "this text between the quotes" is a string. In most programming languages, dividing a number by a string has no meaning. Most modern programming languages will therefore reject any program attempting to perform such an operation. In some languages, the meaningless operation will be detected when the program is compiled ("static" type checking), and rejected by the compiler, while in others, it will be detected when the program is run ("dynamic" type checking), resulting in a runtime exception. Exception handling is a programming language construct or computer hardware mechanism designed to handle the occurrence of a condition that changes the normal flow of execution

A special case of typed languages are the single-type languages. These are often scripting or markup languages, such as Rexx or SGML, and have only one data type — most commonly character strings which are used for both symbolic and numeric data. REXX (REstructured eXtended eXecutor is an interpreted Programming language which was developed at IBM. The Standard Generalized Markup Language ( ISO 88791986 SGML) is an ISO Standard Metalanguage in which one can define Markup languages

In contrast, an untyped language, such as most assembly languages, allows any operation to be performed on any data, which are generally considered to be sequences of bits of various lengths. See the terminology section below for information regarding inconsistent use of the terms assembly and assembler ^[14] High-level languages which are untyped include BCPL and some varieties of Forth. Forth is a structured, imperative, stack-based, computer Programming language and programming environment

In practice, while few languages are considered typed from the point of view of type theory (verifying or rejecting all operations), most modern languages offer a degree of typing. In Mathematics, Logic and Computer science, type theory is any of several Formal systems that can serve as alternatives to Naive set theory ^[14] Many production languages provide means to bypass or subvert the type system.

Static versus dynamic typing

In static typing all expressions have their types determined prior to the program being run (typically at compile-time). In Computer science, a type system defines how a Programming language classifies values and expressions into '''types''', how it can For example, 1 and (2+2) are integer expressions; they cannot be passed to a function that expects a string, or stored in a variable that is defined to hold dates. ^[14]

Statically-typed languages can be manifestly typed or type-inferred. Type inference, or implicit typing, refers to the ability to deduce automatically the type of a value in a Programming language. In the first case, the programmer must explicitly write types at certain textual positions (for example, at variable declarations). In Programming languages, a declaration specifies the Identifier, type, and other aspects of language elements such as variables and functions In the second case, the compiler infers the types of expressions and declarations based on context. Most mainstream statically-typed languages, such as C++, C# and Java, are manifestly typed. C++ (" C Plus Plus " ˌsiːˌplʌsˈplʌs is a general-purpose Programming language. C# (pronounced C Sharp is a Multi-paradigm Complete type inference has traditionally been associated with less mainstream languages, such as Haskell and ML. Haskell is a standardized Purely functional Programming language with non-strict semantics, named after the Logician Haskell Curry ML is a general-purpose Functional programming language developed by Robin Milner and others in the late 1970s at the University of Edinburgh, whose syntax However, many manifestly typed languages support partial type inference; for example, Java and C# both infer types in certain limited cases. C# (pronounced C Sharp is a Multi-paradigm ^[15] Dynamic typing, also called latent typing, determines the type-safety of operations at runtime; in other words, types are associated with runtime values rather than textual expressions. ^[14] As with type-inferred languages, dynamically typed languages do not require the programmer to write explicit type annotations on expressions. Among other things, this may permit a single variable to refer to values of different types at different points in the program execution. However, type errors cannot be automatically detected until a piece of code is actually executed, making debugging more difficult. Ruby, Lisp, JavaScript, and Python are dynamically typed. Ruby is a dynamic, reflective, general purpose Object-oriented programming language that combines syntax inspired by Perl with Smalltalk Lisp (or LISP) is a family of Computer Programming languages with a long history and a distinctive fully parenthesized syntax JavaScript is a Scripting language most often used for Client-side web development Python is a general-purpose High-level programming language. Its design philosophy emphasizes programmer productivity and code readability

Weak and strong typing

Weak typing allows a value of one type to be treated as another, for example treating a string as a number. ^[14] This can occasionally be useful, but it can also allow some kinds of program faults to go undetected at compile time and even at run time. In Computer science, compile time refers to either the operations performed by a Compiler (the "compile-time operations" or Programming language

Strong typing prevents the above. An attempt to perform an operation on the wrong type of value raises an error. ^[14] Strongly-typed languages are often termed type-safe or safe. In Computer science, type safety is a property of some Programming languages that is defined differently by different communities but most definitions involve

An alternative definition for "weakly typed" refers to languages, such as Perl, JavaScript, and C++, which permit a large number of implicit type conversions. NOTES FOR EDITORS "Perl" is not an acronym (read the "Name" section below JavaScript is a Scripting language most often used for Client-side web development C++ (" C Plus Plus " ˌsiːˌplʌsˈplʌs is a general-purpose Programming language. In JavaScript, for example, the expression 2 * x implicitly converts x to a number, and this conversion succeeds even if x is null, undefined, an Array, or a string of letters. Such implicit conversions are often useful, but they can mask programming errors.

Strong and static are now generally considered orthogonal concepts, but usage in the literature differs. Some use the term strongly typed to mean strongly, statically typed, or, even more confusingly, to mean simply statically typed. Thus C has been called both strongly typed and weakly, statically typed. tags please moot on the talk page first! --> In Computing, C is a general-purpose cross-platform block structured ^[16][17]

Execution semantics

Once data has been specified, the machine must be instructed to perform operations on the data. The execution semantics of a language defines how and when the various constructs of a language should produce a program behavior.

For example, the semantics may define the strategy by which expressions are evaluated to values, or the manner in which control structures conditionally execute statements. In Computer science, an evaluation strategy is a set of (usually deterministic rules for determining the evaluation of expressions in a Programming language In Computer science control flow (or alternatively flow of control refers to the order in which the individual statements, instructions or Function

Core library

For more details on this topic, see Standard library. A standard library for a Programming language is the library that is conventionally made available in every implementation of that language

Most programming languages have an associated core library (sometimes known as the 'Standard library', especially if it is included as part of the published language standard), which is conventionally made available by all implementations of the language. In Computer science, a library is a collection of Subroutines used to develop Software. Core libraries typically include definitions for commonly used algorithms, data structures, and mechanisms for input and output.

A language's core library is often treated as part of the language by its users, although the designers may have treated it as a separate entity. Many language specifications define a core that must be made available in all implementations, and in the case of standardized languages this core library may be required. The line between a language and its core library therefore differs from language to language. Indeed, some languages are designed so that the meanings of certain syntactic constructs cannot even be described without referring to the core library. For example, in Java, a string literal is defined as an instance of the java. lang. String class; similarly, in Smalltalk, an anonymous function expression (a "block") constructs an instance of the library's BlockContext class. Smalltalk is an object-oriented, dynamically typed, reflective programming language. In Computing, an anonymous function is a function (or a Subroutine) defined and possibly called without being bound to a name Conversely, Scheme contains multiple coherent subsets that suffice to construct the rest of the language as library macros, and so the language designers do not even bother to say which portions of the language must be implemented as language constructs, and which must be implemented as parts of a library. Scheme is a Multi-paradigm programming language. It is one of the two main dialects of Lisp and supports a number of programming paradigms but is

Practice

A language's designers and users must construct a number of artifacts that govern and enable the practice of programming. The most important of these artifacts are the language specification and implementation.

Specification

For more details on this topic, see Programming language specification. A programming language specification is an artifact that defines a Programming language so that users and implementors can agree on what programs in that

The specification of a programming language is intended to provide a definition that language users and implementors can use to determine the behavior of a program, given its source code. A programmer is someone who writes Computer software. The term computer programmer can refer to a specialist in one area of computer programming or to a generalist A programming language implementation is a system for executing programs written in a Programming language. Computer programs (also software programs, or just programs) are instructions for a Computer. In Computer science, source code (commonly just source or code) is any sequence of statements or declarations written in some Human-readable

A programming language specification can take several forms, including the following:

• An explicit definition of the syntax, static semantics, and execution semantics of the language. While syntax is commonly specified using a formal grammar, semantic definitions may be written in natural language (e. In the Philosophy of language, a natural language (or ordinary language) is a Language that is spoken or written in phonemic-alphabetic or phonemically-related g. , the C language), or a formal semantics (e. tags please moot on the talk page first! --> In Computing, C is a general-purpose cross-platform block structured In Theoretical computer science, formal semantics is the field concerned with the rigorous mathematical study of the meaning of Programming languages and models of g. , the Standard ML^[18] and Scheme^[19] specifications). Standard ML ( SML) is a general-purpose modular, Functional programming language with Compile-time type checking and Type inference Scheme is a Multi-paradigm programming language. It is one of the two main dialects of Lisp and supports a number of programming paradigms but is
• A description of the behavior of a translator for the language (e. A compiler is a Computer program (or set of programs that translates text written in a computer language (the source language) into another g. , the C++ and Fortran specifications). C++ (" C Plus Plus " ˌsiːˌplʌsˈplʌs is a general-purpose Programming language. Fortran (previously FORTRAN) is a general-purpose, procedural, imperative Programming language that is especially suited to The syntax and semantics of the language have to be inferred from this description, which may be written in natural or a formal language.
• A reference or model implementation, sometimes written in the language being specified (e. g. , Prolog or ANSI REXX^[20]). Prolog is a Logic programming language It is a general purpose language often associated with Artificial intelligence and Computational linguistics REXX (REstructured eXtended eXecutor is an interpreted Programming language which was developed at IBM. The syntax and semantics of the language are explicit in the behavior of the reference implementation.

Implementation

For more details on this topic, see Programming language implementation. A programming language implementation is a system for executing programs written in a Programming language.

An implementation of a programming language provides a way to execute that program on one or more configurations of hardware and software. There are, broadly, two approaches to programming language implementation: compilation and interpretation. A compiler is a Computer program (or set of programs that translates text written in a computer language (the source language) into another In Computer science, an interpreter normally means a Computer program that executes, i It is generally possible to implement a language using either technique.

The output of a compiler may be executed by hardware or a program called an interpreter. A compiler is a Computer program (or set of programs that translates text written in a computer language (the source language) into another In some implementations that make use of the interpreter approach there is no distinct boundary between compiling and interpreting. For instance, some implementations of the BASIC programming language compile and then execute the source a line at a time. In Computer programming, BASIC (an Acronym for Beginner's All-purpose Symbolic Instruction Code) is a family of High-level programming languages

Programs that are executed directly on the hardware usually run several orders of magnitude faster than those that are interpreted in software.

One technique for improving the performance of interpreted programs is just-in-time compilation. In Computing, just-in-time compilation ( JIT) also known as dynamic translation, is a technique for improving the runtime performance of a Computer Here the virtual machine monitors which sequences of bytecode are frequently executed and translates them to machine code for direct execution on the hardware. In Computer science, a virtual machine (VM is a Software implementation of a machine (computer that executes programs like a real machine Bytecode is a term which has been used to denote various forms of Instruction sets designed for efficient execution by a software interpreter as well as being suitable

History

A selection of textbooks that teach programming, in languages both popular and obscure. These are only a few of the thousands of programming languages and dialects that have been designed in history.

For more details on this topic, see History of programming languages. This article discusses the major developments in the history of Programming languages.

Early developments

The first programming languages predate the modern computer. The 19th century had "programmable" looms and player piano scrolls which implemented what are today recognized as examples of domain-specific programming languages. A loom is a Machine or device for Weaving thread or Yarn into Textiles Looms can range from very small hand-held frames to large free-standing The player piano is a self-playing Piano, containing a pneumatic mechanism that plays on the piano action pre-programmed Music via perforated paper rolls The term domain-specific language ( DSL) has become popular in recent years in Software development to indicate a Programming language or Specification By the beginning of the twentieth century, punch cards encoded data and directed mechanical processing. In the 1930s and 1940s, the formalisms of Alonzo Church's lambda calculus and Alan Turing's Turing machines provided mathematical abstractions for expressing algorithms; the lambda calculus remains influential in language design. Alonzo Church ( June 14, 1903 – August 11, 1995) was an American Mathematician and logician In Mathematical logic and Computer science, lambda calculus, also written as λ-calculus, is a Formal system designed to investigate function Alan Mathison Turing, OBE, FRS (ˈt(jʊ(ərɪŋ (23 June 1912 &ndash 7 June 1954 was an English Mathematician Turing machines are basic abstract symbol-manipulating devices which despite their simplicity can be adapted to simulate the logic of any Computer Algorithm In Mathematics, Computing, Linguistics and related subjects an algorithm is a sequence of finite instructions often used for Calculation ^[21]

In the 1940s, the first electrically powered digital computers were created. The computers of the early 1950s, notably the UNIVAC I and the IBM 701 used machine language programs. The UNIVAC I ( U N I V ersal A utomatic C omputer I) was the first commercial computer made in the United States The IBM 701, known as the Defense Calculator while in development was announced to the public on April 29, Machine code or machine language is a system of instructions and data executed directly by a Computer 's Central processing unit. First generation machine language programming was quickly superseded by a second generation of programming languages known as Assembly languages. A first-generation Programming language is a machine-level programming language Second-generation programming language is a generational way to categorize Assembly languages The term was coined to provide a distinction from higher level Third-generation See the terminology section below for information regarding inconsistent use of the terms assembly and assembler Later in the 1950s, assembly language programming, which had evolved to include the use of macro instructions, was followed by the development of three higher-level programming languages: FORTRAN, LISP, and COBOL. A macro instruction is a line of computer program coding that results in one or more lines of program coding in the target programming language Fortran (previously FORTRAN) is a general-purpose, procedural, imperative Programming language that is especially suited to Lisp (or LISP) is a family of Computer Programming languages with a long history and a distinctive fully parenthesized syntax COBOL (ˈkoʊbɒl is one of the oldest programming languages still in active use Updated versions of all of these are still in general use, and importantly, each has strongly influenced the development of later languages. ^[22] At the end of the 1950s, the language formalized as Algol 60 was introduced, and most later programming languages are, in many respects, descendants of Algol. Algol (β Per / Beta Persei known colloquially as the Demon Star, is a bright Star in the Constellation Perseus. ^[22] The format and use of the early programming languages was heavily influenced by the constraints of the interface. From the invention of computer Programming languages into the 1980s many if not most computer programmers created edited and stored their programs on Punch cards The practice ^[23]

Refinement

The period from the 1960s to the late 1970s brought the development of the major language paradigms now in use, though many aspects were refinements of ideas in the very first Third-generation programming languages:

• APL introduced array programming and influenced functional programming. A third-generation language ( 3GL) is a Programming language designed to be easier for a human to understand including things like named variables abstract data types In Computer science, array programming languages (also known as vector or multidimensional languages generalize operations on scalars to apply In Computer science, functional programming is a Programming paradigm that treats Computation as the evaluation of mathematical functions and ^[24]
• PL/I (NPL) was designed in the early 1960s to incorporate the best ideas from FORTRAN and COBOL. PL/I ("Programming Language One" ˌpiːˌɛlˈwʌn is an imperative computer Programming language designed for scientific engineering
• In the 1960s, Simula was the first language designed to support object-oriented programming; in the mid-1970s, Smalltalk followed with the first "purely" object-oriented language. Simula is a name for two programming languages Simula I and Simula 67 developed in the 1960s at the Norwegian Computing Center in Oslo, by Ole-Johan Dahl Object-oriented programming (OOP is a Programming paradigm that uses " objects " and their interactions to design applications and computer programs Smalltalk is an object-oriented, dynamically typed, reflective programming language.
• C was developed between 1969 and 1973 as a systems programming language, and remains popular. tags please moot on the talk page first! --> In Computing, C is a general-purpose cross-platform block structured Systems programming (or system programming) is the activity of Programming System software. ^[25]
• Prolog, designed in 1972, was the first logic programming language. Prolog is a Logic programming language It is a general purpose language often associated with Artificial intelligence and Computational linguistics Logic programming is in its broadest sense the use of mathematical logic for computer programming
• In 1978, ML built a polymorphic type system on top of Lisp, pioneering statically typed functional programming languages. ML is a general-purpose Functional programming language developed by Robin Milner and others in the late 1970s at the University of Edinburgh, whose syntax In Computer science, a type system defines how a Programming language classifies values and expressions into '''types''', how it can In Computer science, functional programming is a Programming paradigm that treats Computation as the evaluation of mathematical functions and

Each of these languages spawned an entire family of descendants, and most modern languages count at least one of them in their ancestry.

The 1960s and 1970s also saw considerable debate over the merits of structured programming, and whether programming languages should be designed to support it. Structured programming can be seen as a subset or subdiscipline of Procedural programming, one of the major Programming paradigms It is most famous for removing or ^[26] Edsger Dijkstra, in a famous 1968 letter published in the Communications of the ACM, argued that GOTO statements should be eliminated from all "higher level" programming languages. Edsger Wybe Dijkstra ( May 11, 1930 &ndash August 6, 2002; ˈɛtsxər ˈwibə ˈdɛɪkstra was a Dutch computer scientist Communications of the ACM ( CACM) is the flagship monthly Journal of the Association for Computing Machinery (ACM GOTO is a statement found in many computer Programming languages It is a combination of the English words go and to ^[27]

The 1960s and 1970s also saw expansion of techniques that reduced the footprint of a program as well as improved productivity of the programmer and user. The card deck for an early 4GL was a lot smaller for the same functionality expressed in a 3GL deck. From the invention of computer Programming languages into the 1980s many if not most computer programmers created edited and stored their programs on Punch cards The practice A fourth-generation programming language (1970s-1990 (abbreviated 4GL) is a Programming language or programming environment designed with a specific purpose in mind A third-generation language ( 3GL) is a Programming language designed to be easier for a human to understand including things like named variables abstract data types

Consolidation and growth

The 1980s were years of relative consolidation. C++ combined object-oriented and systems programming. C++ (" C Plus Plus " ˌsiːˌplʌsˈplʌs is a general-purpose Programming language. The United States government standardized Ada, a systems programming language intended for use by defense contractors. Ada is a structured, Statically typed, imperative, and object-oriented high-level computer Programming language In Japan and elsewhere, vast sums were spent investigating so-called "fifth generation" languages that incorporated logic programming constructs. For the Fifth Generation of Chinese filmmakers see Cinema of China-The rise of the Fifth Generation. ^[28] The functional languages community moved to standardize ML and Lisp. Rather than inventing new paradigms, all of these movements elaborated upon the ideas invented in the previous decade.

One important trend in language design during the 1980s was an increased focus on programming for large-scale systems through the use of modules, or large-scale organizational units of code. Modula-2, Ada, and ML all developed notable module systems in the 1980s, although other languages, such as PL/I, already had extensive support for modular programming. Modula-2 is a computer Programming language invented by Niklaus Wirth at ETH, around 1978 as a successor to his intermediate language Modula PL/I ("Programming Language One" ˌpiːˌɛlˈwʌn is an imperative computer Programming language designed for scientific engineering Module systems were often wedded to generic programming constructs. Generic programming is a style of Computer programming in which algorithms are written in terms of to-be-specified-later types that are then instantiated ^[29]

The rapid growth of the Internet in the mid-1990's created opportunities for new languages. The Internet is a global system of interconnected Computer networks Perl, originally a Unix scripting tool first released in 1987, became common in dynamic Web sites. NOTES FOR EDITORS "Perl" is not an acronym (read the "Name" section below A website (alternatively web site or Web site, a back-construction from the Proper noun World Wide Web) is a collection of Web pages Java came to be used for server-side programming. These developments were not fundamentally novel, rather they were refinements to existing languages and paradigms, and largely based on the C family of programming languages.

Programming language evolution continues, in both industry and research. Current directions include security and reliability verification, new kinds of modularity (mixins, delegates, aspects), and database integration. In Object-oriented programming languages a mixin is a class that provides a certain functionality to be inherited by a subclass but is not meant to stand In Object-oriented programming there are two related notions of delegation. Aspect-oriented programming ( AOP) is a Programming paradigm that increases modularity by allowing the separation of Cross-cutting concerns

The 4GLs are examples of languages which are domain-specific, such as SQL, which manipulates and returns sets of data rather than the scalar values which are canonical to most programming languages. A fourth-generation programming language (1970s-1990 (abbreviated 4GL) is a Programming language or programming environment designed with a specific purpose in mind Perl, for example, with its 'here document' can hold multiple 4GL programs, as well as multiple JavaScript programs, in part of its own perl code and use variable interpolation in the 'here document' to support multi-language programming. NOTES FOR EDITORS "Perl" is not an acronym (read the "Name" section below A here document (also called a here-document or a heredoc) is a way of specifying a String literal in command line shells such as Bash ^[30]

Measuring language usage

It is difficult to determine which programming languages are most widely used, and what usage means varies by context. One language may occupy the greater number of programmer hours, a different one have more lines of code, and a third utilize the most CPU time. Some languages are very popular for particular kinds of applications. For example, COBOL is still strong in the corporate data center, often on large mainframes; FORTRAN in engineering applications; C in embedded applications and operating systems; and other languages are regularly used to write many different kinds of applications. COBOL (ˈkoʊbɒl is one of the oldest programming languages still in active use Mainframes (often colloquially referred to as Big Iron) are Computers used mainly by large organizations for critical applications typically bulk data Fortran (previously FORTRAN) is a general-purpose, procedural, imperative Programming language that is especially suited to tags please moot on the talk page first! --> In Computing, C is a general-purpose cross-platform block structured

Various methods of measuring language popularity, each subject to a different bias over what is measured, have been proposed:

• counting the number of job advertisements that mention the language^[31]
• the number of books sold that teach or describe the language^[32]
• estimates of the number of existing lines of code written in the language—which may underestimate languages not often found in public searches^[33]
• counts of language references found using a web search engine.

Taxonomies

For more details on this topic, see Categorical list of programming languages. This is a list of Programming languages grouped by category Array languages CategoryArray programming languages|l1=CategoryArray programming

There is no overarching classification scheme for programming languages. A given programming language does not usually have a single ancestor language. Languages commonly arise by combining the elements of several predecessor languages with new ideas in circulation at the time. Ideas that originate in one language will diffuse throughout a family of related languages, and then leap suddenly across familial gaps to appear in an entirely different family.

The task is further complicated by the fact that languages can be classified along multiple axes. For example, Java is both an object-oriented language (because it encourages object-oriented organization) and a concurrent language (because it contains built-in constructs for running multiple threads in parallel). A thread in Computer science is short for a thread of execution. Python is an object-oriented scripting language. Python is a general-purpose High-level programming language. Its design philosophy emphasizes programmer productivity and code readability "Scripting" redirects here For other uses see Script.

In broad strokes, programming languages divide into programming paradigms and a classification by intended domain of use. A programming paradigm is a fundamental style of Computer programming. Paradigms include procedural programming, object-oriented programming, functional programming, and logic programming; some languages are hybrids of paradigms or multi-paradigmatic. Procedural programming can sometimes be used as a synonym for Imperative programming (specifying the steps the program must take to reach the desired state but can also Object-oriented programming (OOP is a Programming paradigm that uses " objects " and their interactions to design applications and computer programs In Computer science, functional programming is a Programming paradigm that treats Computation as the evaluation of mathematical functions and Logic programming is in its broadest sense the use of mathematical logic for computer programming An assembly language is not so much a paradigm as a direct model of an underlying machine architecture. See the terminology section below for information regarding inconsistent use of the terms assembly and assembler By purpose, programming languages might be considered general purpose, system programming languages, scripting languages, domain-specific languages, or concurrent/distributed languages (or a combination of these). ^[34] Some general purpose languages were designed largely with educational goals. ^[35]

A programming language may also be classified by factors unrelated to programming paradigm. For instance, most programming languages use English language keywords, while a minority do not. English is a West Germanic language originating in England and is the First language for most people in the United Kingdom, the United States This is a list of Programming languages grouped by category Array languages CategoryArray programming languages|l1=CategoryArray programming Other languages may be classified as being esoteric or not. An esoteric programming language (sometimes shortened to esolang) is a Programming language designed as a test of the boundaries of computer programming language design

See also

• Lists of programming languages
• Comparison of programming languages
• Comparison of basic instructions of programming languages
• Educational programming language
• Invariant based programming
• Literate programming
• Programming language dialect
• Programming language theory
• Computer science and List of basic computer science topics
• Software engineering and List of software engineering topics

References

Further reading

• Daniel P. Friedman, Mitchell Wand, Christopher Thomas Haynes: Essentials of Programming Languages, The MIT Press 2001.
• David Gelernter, Suresh Jagannathan: Programming Linguistics, The MIT Press 1990.
• Shriram Krishnamurthi: Programming Languages: Application and Interpretation, online publication.
• Bruce J. MacLennan: Principles of Programming Languages: Design, Evaluation, and Implementation, Oxford University Press 1999.
• John C. Mitchell: Concepts in Programming Languages, Cambridge University Press 2002.
• Benjamin C. Pierce: Types and Programming Languages, The MIT Press 2002.
• Ravi Sethi: Programming Languages: Concepts and Constructs, 2nd ed. , Addison-Wesley 1996.
• Michael L. Scott: Programming Language Pragmatics, Morgan Kaufmann Publishers 2005.
• Richard L. Wexelblat (ed. ): History of Programming Languages, Academic Press 1981.

External links

• 99 Bottles of Beer A collection of implementations in many languages.
• Computer Languages History graphical chart
• Dictionary of Programming Languages
• History of Programming Languages (HOPL)
• Open Directory - Computer Programming Languages
• Syntax Patterns for Various Languages
• The Evolution of Programming Languages by Peter Grogono