Ousterhout's dichotomy is computer scientist

John Ousterhout John Kenneth Ousterhout (, born October 15, 1954) is a professor of computer science at Stanford University. He founded Electric Cloud with John Graham-Cumming. Ousterhout was a professor of computer science at University of California, Berkeley ...

's categorization that

high-level programming language In computer science, a high-level programming language is a programming language with strong abstraction from the details of the computer. In contrast to low-level programming languages, it may use natural language ''elements'', be easier to us ...

s tend to fall into two groups, each with distinct properties and uses: ''

system programming Systems programming, or system programming, is the activity of programming computer system software. The primary distinguishing characteristic of systems programming when compared to application programming is that application programming aims to pr ...

languages'' and ''

scripting language A scripting language or script language is a programming language that is used to manipulate, customize, and automate the facilities of an existing system. Scripting languages are usually interpreted at runtime rather than compiled. A scripting ...

s'' – compare

programming in the large and programming in the small In software engineering, programming in the large and programming in the small refer to two different aspects of writing software, namely, designing a larger system as a composition of smaller parts, and creating those smaller parts by writing li ...

. This distinction underlies the design of his language

Tcl TCL or Tcl or TCLs may refer to: Business * TCL Technology, a Chinese consumer electronics and appliance company **TCL Electronics, a subsidiary of TCL Technology * Texas Collegiate League, a collegiate baseball league * Trade Centre Limited ...

. System programming languages (or ''applications languages'') usually have the following properties: * They are typed statically * They support creating complex data structures * Programs in them are compiled into

machine code In computer programming, machine code is any low-level programming language, consisting of machine language instructions, which are used to control a computer's central processing unit (CPU). Each instruction causes the CPU to perform a ve ...

* Programs in them are meant to operate largely independently of other programs System programming languages tend to be used for components and applications with large amounts of internal functionality such as operating systems, database servers, and Web browsers. These applications typically employ complex algorithms and data structures and require high performance. Prototypical examples of system programming languages include C, OCaml and Modula-2. By contrast, scripting languages (or ''

glue language A scripting language or script language is a programming language that is used to manipulate, customize, and automate the facilities of an existing system. Scripting languages are usually interpreted at runtime rather than compiled. A scripting ...

s'') tend to have the following properties: * They are typed dynamically * They have little or no provision for complex data structures * Programs in them (''scripts'') are interpreted Scripting languages tend to be used for applications where most of the functionality comes from other programs (often implemented in system programming languages); the scripts are used to ''glue'' together other programs or add additional layers of functionality on top of existing programs. Ousterhout claims that scripts tend to be short and are often written by less sophisticated programmers, so execution efficiency is less important than simplicity and ease of interaction with other programs. Common applications for scripting include Web page generation, report generation, graphical user interfaces, and system administration. Prototypical examples of scripting languages include

Python Python may refer to: Snakes * Pythonidae, a family of nonvenomous snakes found in Africa, Asia, and Australia ** ''Python'' (genus), a genus of Pythonidae found in Africa and Asia * Python (mythology), a mythical serpent Computing * Python (pro ...

AppleScript AppleScript is a scripting language created by Apple Inc. that facilitates automated control over scriptable Mac applications. First introduced in System 7, it is currently included in all versions of macOS as part of a package of system aut ...

C shell The C shell (csh or the improved version, tcsh) is a Unix shell created by Bill Joy while he was a graduate student at University of California, Berkeley in the late 1970s. It has been widely distributed, beginning with the 2BSD release of th ...

DOS DOS is shorthand for the MS-DOS and IBM PC DOS family of operating systems. DOS may also refer to: Computing * Data over signalling (DoS), multiplexing data onto a signalling channel * Denial-of-service attack (DoS), an attack on a communicat ...

batch file Batch may refer to: Food and drink * Batch (alcohol), an alcoholic fruit beverage * Batch loaf, a type of bread popular in Ireland * A dialect term for a bread roll used in North Warwickshire, Nuneaton and Coventry, as well as on the Wirra ...

s, and

History

The dichotomy was fully set out in , though Ousterhout had drawn this distinction since at least the design of Tcl (1988), and had stated it publicly at various times. An early episode was
The Tcl War
of late September and October 1994, where

Richard Stallman Richard Matthew Stallman (; born March 16, 1953), also known by his initials, rms, is an American free software movement activist and programmer. He campaigns for software to be distributed in such a manner that its users have the freedom to ...

posted an article critical of Tcl, entitled "Why you should not use Tcl", to which Ousterhout replied with an articulation of his dichotomy:

Criticism

Critics believe that the dichotomy is highly arbitrary, and refer to it as ''Ousterhout's fallacy'' or ''Ousterhout's false dichotomy''. While static-versus-dynamic typing, data structure complexity, and dependent versus stand-alone might be said to be unrelated features, the usual critique of Ousterhout's dichotomy is of its distinction of compiling versus interpreting. Neither semantics nor syntax depend significantly on whether a language implementation compiles into machine language, interprets, tokenizes, or byte-compiles at the start of each run, or any mix of these. In addition, basically no languages in widespread use are purely interpreted without a compiler; this makes compiling versus interpreting a dubious parameter in a taxonomy of programming languages.

References

External links

Ousterhout's dichotomy
at the

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Programming language folklore Software engineering folklore Programming paradigms Dichotomies

History

Criticism

References

Further reading

External links