Programming language generations
Encyclopedia
Programming language
s have been classified into several programming language generations. Historically, this classification was used to indicate increasing power of programming styles. Later writers have somewhat redefined the meanings as distinctions previously seen as important became less significant to current practice.
programming languages, discussed below, giving technical content to the second/third-generation distinction among high level programming languages as well, and reflexively renaming assembler languages as first-generation.
said about coding in machine language: "We were not programmers in those days. The word had not yet come over from England. We were coders.The task of encoding an algorithm wasn’t thought of as writing in a language any more than was the task of wiring a plug-board. But even by the early 1950s, the assembly language
s were seen as a distinct "epoch". The distinguishing properties of these first generation programming languages are that:
First-generation languages are sometimes used in kernels and device drivers, but more often find use in extremely intensive processing such as games, video editing, and graphic manipulation/rendering.
reflecting the needs of scientific programmers, ALGOL
reflecting an attempt to produce a European/American standard view.
The most important issue faced by the developers of second-level languages was convincing customers that the code produced by the compilers performed well-enough to justify abandonment of assembler programming. In view of the widespread skepticism about the possibility of producing efficient programs with an automatic programming system and the fact that inefficiencies could no longer be hidden, we were convinced that the kind of system we had in mind would be widely used only if we could demonstrate that it would produce programs almost as efficient as hand coded ones and do so on virtually every job.The FORTRAN compiler was seen as a tour-de-force in the production of high-quality code, even including "… a Monte Carlo simulation of its execution … so as to minimize the transfers of items between the store and the index registers
Second-generation programming languages evolved through the decade. FORTRAN lost some of its machine-dependent features, like access to the lights and switches on the operator console. Most second-generation languages employed a static storage model in which storage for data was allocated only once, when a program is loaded, making recursion difficult, but Algol evolved to provide block-structured naming constructs and began to expand the set of features made available to programmers, like concurrency management. In this way (Algol 68
) began the movement into a new generation of programming languages..
Some or all of a number of other developments that occurred at the same time were included in 3GLs.
Interpretation
was introduced. Some 3GLs were compiled, a process analogous to the creation of a complete machine code executable from assembly code, the difference being that in higher-level languages there is no longer a one-to-one, or even linear, relationship between source code instructions and machine code instructions. Compilers are able to target different hardware by producing different translations of the same source code commands.
Interpreters, on the other hand, essentially execute the source code instructions themselves — if one encounters an "add" instruction, it performs an addition itself, rather than outputting an addition instruction to be executed later. Machine-independence is achieved by having different interpreters in the machine codes of the targeted platforms, ie the interpreter itself generally has to be compiled. Interpretation was not a linear "advance", but an alternative model to compilation, which continues to exist alongside it, and other, more recently developed, hybrids. Lisp is an early interprepreted language.
The earliest 3GLs, such as Fortran
and Cobol
, were spaghetti code
d, ie they had the same style of flow of control as assembler
and machine code
, making heavy use of the goto
statement. Structured programming
introduced a model where a programme was seen as a hierarchy
of nested blocks
rather than a linear list of instructions. for instance, structured programmers were to conceive of a loop as a block of code that is repeated, rather than
so many commands followed by a backwards jump or goto. Structured programming is less about power — in the sense of one higher-level commannd expanding into many lower-level ones — than safety. Programmers following it were much less prone to make mistakes. The division of code into blocks, subroutines and other modules with clearly-defined interfaces also had productivity benefits in allowing many programmer to work on one project. Once introduced (in the ALGOL
language), structured programming was incorporated into almost all languages, and retrofit
ted to languages that did not originally have it, such as Fortran
, etc.
Block structure
was also associated with deprecation of global variables, a similar source of error to
Another high-level feature was the development of type systems that went beyond the data types of the underlying machine code, such as strings, arrays and records.
Where early 3GLs were special-purpose, (eg. science or commerce) an attempt was made to create general-purpose languages, such as C and Pascal. Whilst, these enjoyed some success, domain specific languages did not disappear.
is a machine-level programming language.
Originally, no translator was used to compile
or assemble
the first-generation language. The first-generation programming instructions were entered through the front panel switches of the computer system.
The main benefit of programming in a first-generation programming language is that the code a user writes can run very fast and efficiently, since it is directly executed by the CPU
. However, machine language is a lot more difficult to learn than higher generational programming languages, and it is far more difficult to edit if errors occur. In addition, if instructions need to be added into memory at some location, then all the instructions after the insertion point need to be moved down to make room in memory to accommodate the new instructions. Doing so on a front panel with switches can be very difficult.
is a generational way to categorize assembly language
s. The term was coined to provide a distinction from higher level third-generation programming language
s (3GL) such as COBOL
and earlier machine code languages
. Second-generation programming languages have the following properties:
Second-generation languages are sometimes used in kernels and device drivers (though C
is generally employed for this in modern kernels), but more often find use in extremely intensive processing such as games, video editing, graphic manipulation/rendering.
One method for creating such code is by allowing a compiler to generate a machine-optimized assembly language version of a particular function. This code is then hand-tuned, gaining both the brute-force insight of the machine optimizing algorithm and the intuitive abilities of the human optimizer.
(3GL) is a refinement of a second-generation programming language
. Whereas a second generation language is more aimed to fix logical structure to the language, a third generation language aims to refine the usability of the language in such a way to make it more user friendly. This could mean restructuring categories of possible functions to make it more efficient, condensing the overall bulk of code via classes (eg. Visual Basic
). A third generation language improves over a second generation language by having more refinement on the usability of the language itself from the perspective of the user.
First introduced in the late 1950s, FORTRAN
, ALGOL
and COBOL
are early examples of this sort of language.
Most "modern" languages (BASIC
, C
, C++
, C#, Pascal, and Java
) are also third-generation languages.
Most 3GLs support structured programming
.
gave rise to C++
and later to Java
and C#, Lisp to CLOS, ADA to ADA95
, and even COBOL to COBOL2002
, and new languages have emerged in that "generation" as well.
But significantly different languages and systems were already being called fourth and fifth generation programming languages by language communities with special interests. The manner in which these generations have been put forward tends to differ in character from those of earlier generations, and they represent software points-of-view leading away from the mainstream.
Programming language
A programming language is an artificial language designed to communicate instructions to a machine, particularly a computer. Programming languages can be used to create programs that control the behavior of a machine and/or to express algorithms precisely....
s have been classified into several programming language generations. Historically, this classification was used to indicate increasing power of programming styles. Later writers have somewhat redefined the meanings as distinctions previously seen as important became less significant to current practice.
Historical view of first three generations
The terms "first-generation" and "second-generation" programming language were not used prior to the coining of the term "third-generation." In fact, none of these three terms are mentioned in an early compendium of programming language.The introduction of a third generation of computer technology coincided with the creation of a new generation of programming languages. The marketing for this generational shift in machines did correlate with several important changes in what were called high levelHigh level
High Level may refer to:In computing*High-level assembler, a type of assembly language translator*High Level Architecture , a military computer simulation framework*High-level programming language, a type of computer programming language...
programming languages, discussed below, giving technical content to the second/third-generation distinction among high level programming languages as well, and reflexively renaming assembler languages as first-generation.
First generation
As Grace HopperGrace Hopper
Rear Admiral Grace Murray Hopper was an American computer scientist and United States Navy officer. A pioneer in the field, she was one of the first programmers of the Harvard Mark I computer, and developed the first compiler for a computer programming language...
said about coding in machine language: "We were not programmers in those days. The word had not yet come over from England. We were coders.The task of encoding an algorithm wasn’t thought of as writing in a language any more than was the task of wiring a plug-board. But even by the early 1950s, the assembly language
Assembly language
An assembly language is a low-level programming language for computers, microprocessors, microcontrollers, and other programmable devices. It implements a symbolic representation of the machine codes and other constants needed to program a given CPU architecture...
s were seen as a distinct "epoch". The distinguishing properties of these first generation programming languages are that:
- The code can be read and written by a programmer. To run on a computer it must be converted into a machine readable form, a process called assembly.
- The language is specific to a particular target machine or family of machines, directly reflecting their characteristics like instruction sets, registers, storage access models, etc., requiring and enabling the programmer to manage their use.
- Some assembler languages provide a macro-facility enabling the development of complex patterns of machine instructions, but these are not considered to change the basic nature of the language.
First-generation languages are sometimes used in kernels and device drivers, but more often find use in extremely intensive processing such as games, video editing, and graphic manipulation/rendering.
Second generation
Second-generation programming languages, originally just called high level programming languages, were created to simplify the burden of programming by making its expression more like the normal mode of expression for thoughts used by the programmer. They were introduced in the late 1950s, with FORTRANFortran
Fortran is a general-purpose, procedural, imperative programming language that is especially suited to numeric computation and scientific computing...
reflecting the needs of scientific programmers, ALGOL
ALGOL
ALGOL is a family of imperative computer programming languages originally developed in the mid 1950s which greatly influenced many other languages and became the de facto way algorithms were described in textbooks and academic works for almost the next 30 years...
reflecting an attempt to produce a European/American standard view.
The most important issue faced by the developers of second-level languages was convincing customers that the code produced by the compilers performed well-enough to justify abandonment of assembler programming. In view of the widespread skepticism about the possibility of producing efficient programs with an automatic programming system and the fact that inefficiencies could no longer be hidden, we were convinced that the kind of system we had in mind would be widely used only if we could demonstrate that it would produce programs almost as efficient as hand coded ones and do so on virtually every job.The FORTRAN compiler was seen as a tour-de-force in the production of high-quality code, even including "… a Monte Carlo simulation of its execution … so as to minimize the transfers of items between the store and the index registers
Second-generation programming languages evolved through the decade. FORTRAN lost some of its machine-dependent features, like access to the lights and switches on the operator console. Most second-generation languages employed a static storage model in which storage for data was allocated only once, when a program is loaded, making recursion difficult, but Algol evolved to provide block-structured naming constructs and began to expand the set of features made available to programmers, like concurrency management. In this way (Algol 68
ALGOL 68
ALGOL 68 isan imperative computerprogramming language that was conceived as a successor to theALGOL 60 programming language, designed with the goal of a...
) began the movement into a new generation of programming languages..
Third generation
The introduction of a third generation of computer technology coincided with the creation of a new generation of programming languages. The essential feature of third-generation languages is their hardware-independence, ie. expression of an algorithm in a way that was independent of the characteristics of the machine on which the algorithm would run.Some or all of a number of other developments that occurred at the same time were included in 3GLs.
Interpretation
Interpreter (computing)
In computer science, an interpreter normally means a computer program that executes, i.e. performs, instructions written in a programming language...
was introduced. Some 3GLs were compiled, a process analogous to the creation of a complete machine code executable from assembly code, the difference being that in higher-level languages there is no longer a one-to-one, or even linear, relationship between source code instructions and machine code instructions. Compilers are able to target different hardware by producing different translations of the same source code commands.
Interpreters, on the other hand, essentially execute the source code instructions themselves — if one encounters an "add" instruction, it performs an addition itself, rather than outputting an addition instruction to be executed later. Machine-independence is achieved by having different interpreters in the machine codes of the targeted platforms, ie the interpreter itself generally has to be compiled. Interpretation was not a linear "advance", but an alternative model to compilation, which continues to exist alongside it, and other, more recently developed, hybrids. Lisp is an early interprepreted language.
The earliest 3GLs, such as Fortran
Fortran
Fortran is a general-purpose, procedural, imperative programming language that is especially suited to numeric computation and scientific computing...
and Cobol
COBOL
COBOL is one of the oldest programming languages. Its name is an acronym for COmmon Business-Oriented Language, defining its primary domain in business, finance, and administrative systems for companies and governments....
, were spaghetti code
Spaghetti code
Spaghetti code is a pejorative term for source code that has a complex and tangled control structure, especially one using many GOTOs, exceptions, threads, or other "unstructured" branching constructs. It is named such because program flow tends to look like a bowl of spaghetti, i.e. twisted and...
d, ie they had the same style of flow of control as assembler
Assembler
Assembler may refer to:* Assembler , for an assembly language, a computer program to translate between lower-level representations of computer programs...
and machine code
Machine code
Machine code or machine language is a system of impartible instructions executed directly by a computer's central processing unit. Each instruction performs a very specific task, typically either an operation on a unit of data Machine code or machine language is a system of impartible instructions...
, making heavy use of the goto
Goto
goto is a statement found in many computer programming languages. It is a combination of the English words go and to. It performs a one-way transfer of control to another line of code; in contrast a function call normally returns control...
statement. Structured programming
Structured programming
Structured programming is a programming paradigm aimed on improving the clarity, quality, and development time of a computer program by making extensive use of subroutines, block structures and for and while loops - in contrast to using simple tests and jumps such as the goto statement which could...
introduced a model where a programme was seen as a hierarchy
Hierarchy
A hierarchy is an arrangement of items in which the items are represented as being "above," "below," or "at the same level as" one another...
of nested blocks
rather than a linear list of instructions. for instance, structured programmers were to conceive of a loop as a block of code that is repeated, rather than
so many commands followed by a backwards jump or goto. Structured programming is less about power — in the sense of one higher-level commannd expanding into many lower-level ones — than safety. Programmers following it were much less prone to make mistakes. The division of code into blocks, subroutines and other modules with clearly-defined interfaces also had productivity benefits in allowing many programmer to work on one project. Once introduced (in the ALGOL
ALGOL
ALGOL is a family of imperative computer programming languages originally developed in the mid 1950s which greatly influenced many other languages and became the de facto way algorithms were described in textbooks and academic works for almost the next 30 years...
language), structured programming was incorporated into almost all languages, and retrofit
Retrofit
Retrofitting refers to the addition of new technology or features to older systems.* power plant retrofit, improving power plant efficiency / increasing output / reducing emissions...
ted to languages that did not originally have it, such as Fortran
Fortran
Fortran is a general-purpose, procedural, imperative programming language that is especially suited to numeric computation and scientific computing...
, etc.
Block structure
Block structure
* In mathematics, block structure is a possible property of matrices - see block matrix.* In computer science, a programming language has block structure if it features blocks which can be nested to any depth....
was also associated with deprecation of global variables, a similar source of error to
goto. Instead, the structured languages introduced lexical scoping and automated management of storage with a stack.Another high-level feature was the development of type systems that went beyond the data types of the underlying machine code, such as strings, arrays and records.
Where early 3GLs were special-purpose, (eg. science or commerce) an attempt was made to create general-purpose languages, such as C and Pascal. Whilst, these enjoyed some success, domain specific languages did not disappear.
Re-characterization of first three generations
Since the 1990s, some authors have recharacterized the development of programming languages in a way that removed the (no longer topical) distinctions between early high-level languages like Fortran or Cobol and later ones, likeFirst generation
In this categorization, a first-generation programming languageProgramming language
A programming language is an artificial language designed to communicate instructions to a machine, particularly a computer. Programming languages can be used to create programs that control the behavior of a machine and/or to express algorithms precisely....
is a machine-level programming language.
Originally, no translator was used to compile
Compile
Compile may refer to:* Compile , a Japanese video game company founded in 1983 that specialized in shoot 'em up and computer puzzle game genres...
or assemble
Assembly language
An assembly language is a low-level programming language for computers, microprocessors, microcontrollers, and other programmable devices. It implements a symbolic representation of the machine codes and other constants needed to program a given CPU architecture...
the first-generation language. The first-generation programming instructions were entered through the front panel switches of the computer system.
The main benefit of programming in a first-generation programming language is that the code a user writes can run very fast and efficiently, since it is directly executed by the CPU
Central processing unit
The central processing unit is the portion of a computer system that carries out the instructions of a computer program, to perform the basic arithmetical, logical, and input/output operations of the system. The CPU plays a role somewhat analogous to the brain in the computer. The term has been in...
. However, machine language is a lot more difficult to learn than higher generational programming languages, and it is far more difficult to edit if errors occur. In addition, if instructions need to be added into memory at some location, then all the instructions after the insertion point need to be moved down to make room in memory to accommodate the new instructions. Doing so on a front panel with switches can be very difficult.
Second generation
Second-generation programming languageProgramming language
A programming language is an artificial language designed to communicate instructions to a machine, particularly a computer. Programming languages can be used to create programs that control the behavior of a machine and/or to express algorithms precisely....
is a generational way to categorize assembly language
Assembly language
An assembly language is a low-level programming language for computers, microprocessors, microcontrollers, and other programmable devices. It implements a symbolic representation of the machine codes and other constants needed to program a given CPU architecture...
s. The term was coined to provide a distinction from higher level third-generation programming language
Third-generation programming language
A third-generation programming language is a refinement of a second-generation programming language. The second generation of programming languages brought logical structure to software. The third generation brought refinements to make the languages more programmer-friendly...
s (3GL) such as COBOL
COBOL
COBOL is one of the oldest programming languages. Its name is an acronym for COmmon Business-Oriented Language, defining its primary domain in business, finance, and administrative systems for companies and governments....
and earlier machine code languages
First-generation programming language
A first-generation programming language is a machine-level programming language.Originally, no translator was used to compile or assemble the first-generation language. The first-generation programming instructions were entered through the front panel switches of the computer system....
. Second-generation programming languages have the following properties:
- The code can be read and written by a programmer. To run on a computer it must be converted into a machine readable form, a process called assembly.
- The language is specific to a particular processor family and environment.
Second-generation languages are sometimes used in kernels and device drivers (though C
C (programming language)
C is a general-purpose computer programming language developed between 1969 and 1973 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system....
is generally employed for this in modern kernels), but more often find use in extremely intensive processing such as games, video editing, graphic manipulation/rendering.
One method for creating such code is by allowing a compiler to generate a machine-optimized assembly language version of a particular function. This code is then hand-tuned, gaining both the brute-force insight of the machine optimizing algorithm and the intuitive abilities of the human optimizer.
Third generation
A third-generation programming languageProgramming language
A programming language is an artificial language designed to communicate instructions to a machine, particularly a computer. Programming languages can be used to create programs that control the behavior of a machine and/or to express algorithms precisely....
(3GL) is a refinement of a second-generation programming language
Second-generation programming language
Second-generation programming language is a generational way to categorise assembly languages. The term was coined to provide a distinction from higher level third-generation programming languages such as COBOL and earlier machine code languages. Second-generation programming languages have the...
. Whereas a second generation language is more aimed to fix logical structure to the language, a third generation language aims to refine the usability of the language in such a way to make it more user friendly. This could mean restructuring categories of possible functions to make it more efficient, condensing the overall bulk of code via classes (eg. Visual Basic
Visual Basic
Visual Basic is the third-generation event-driven programming language and integrated development environment from Microsoft for its COM programming model...
). A third generation language improves over a second generation language by having more refinement on the usability of the language itself from the perspective of the user.
First introduced in the late 1950s, FORTRAN
Fortran
Fortran is a general-purpose, procedural, imperative programming language that is especially suited to numeric computation and scientific computing...
, ALGOL
ALGOL
ALGOL is a family of imperative computer programming languages originally developed in the mid 1950s which greatly influenced many other languages and became the de facto way algorithms were described in textbooks and academic works for almost the next 30 years...
and COBOL
COBOL
COBOL is one of the oldest programming languages. Its name is an acronym for COmmon Business-Oriented Language, defining its primary domain in business, finance, and administrative systems for companies and governments....
are early examples of this sort of language.
Most "modern" languages (BASIC
BASIC
BASIC is a family of general-purpose, high-level programming languages whose design philosophy emphasizes ease of use - the name is an acronym from Beginner's All-purpose Symbolic Instruction Code....
, C
C (programming language)
C is a general-purpose computer programming language developed between 1969 and 1973 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system....
, C++
C++
C++ is a statically typed, free-form, multi-paradigm, compiled, general-purpose programming language. It is regarded as an intermediate-level language, as it comprises a combination of both high-level and low-level language features. It was developed by Bjarne Stroustrup starting in 1979 at Bell...
, C#, Pascal, and Java
Java (programming language)
Java is a programming language originally developed by James Gosling at Sun Microsystems and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities...
) are also third-generation languages.
Most 3GLs support structured programming
Structured programming
Structured programming is a programming paradigm aimed on improving the clarity, quality, and development time of a computer program by making extensive use of subroutines, block structures and for and while loops - in contrast to using simple tests and jumps such as the goto statement which could...
.
Later generations
"Generational" classification of these languages was abandoned after the third-generation languages, with the natural successors to the third-generation languages being termed object-oriented. CC (programming language)
C is a general-purpose computer programming language developed between 1969 and 1973 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system....
gave rise to C++
C++
C++ is a statically typed, free-form, multi-paradigm, compiled, general-purpose programming language. It is regarded as an intermediate-level language, as it comprises a combination of both high-level and low-level language features. It was developed by Bjarne Stroustrup starting in 1979 at Bell...
and later to Java
Java (programming language)
Java is a programming language originally developed by James Gosling at Sun Microsystems and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities...
and C#, Lisp to CLOS, ADA to ADA95
Ada (programming language)
Ada is a structured, statically typed, imperative, wide-spectrum, and object-oriented high-level computer programming language, extended from Pascal and other languages...
, and even COBOL to COBOL2002
COBOL
COBOL is one of the oldest programming languages. Its name is an acronym for COmmon Business-Oriented Language, defining its primary domain in business, finance, and administrative systems for companies and governments....
, and new languages have emerged in that "generation" as well.
But significantly different languages and systems were already being called fourth and fifth generation programming languages by language communities with special interests. The manner in which these generations have been put forward tends to differ in character from those of earlier generations, and they represent software points-of-view leading away from the mainstream.