Greenspun's tenth rule of programming is an

aphorism An aphorism (from Greek ἀφορισμός: ''aphorismos'', denoting 'delimitation', 'distinction', and 'definition') is a concise, terse, laconic, or memorable expression of a general truth or principle. Aphorisms are often handed down by tra ...

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 proc ...

and especially

programming language A programming language is a system of notation for writing computer programs. Programming languages are described in terms of their Syntax (programming languages), syntax (form) and semantics (computer science), semantics (meaning), usually def ...

circles that states:

Overview

The rule expresses the opinion that the argued flexibility and

extensibility Extensibility is a software engineering and systems design principle that provides for future growth. Extensibility is a measure of the ability to extend a system and the level of effort required to implement the extension. Extensions can be t ...

designed into the programming language

Lisp Lisp (historically LISP, an abbreviation of "list processing") is a family of programming languages with a long history and a distinctive, fully parenthesized Polish notation#Explanation, prefix notation. Originally specified in the late 1950s, ...

includes all functionality that is theoretically needed to write any complex computer program, and that the features required to develop and manage such complexity in other programming languages are equivalent to some subset of the methods used in Lisp. Other programming languages, while claiming to be simpler, require programmers to reinvent in a haphazard way a significant amount of needed functionality that is present in Lisp as a standard, time-proven base. It can also be interpreted as a satiric critique of systems that include complex, highly configurable sub-systems. Rather than including a custom

interpreter Interpreting is translation from a spoken or signed language into another language, usually in real time to facilitate live communication. It is distinguished from the translation of a written text, which can be more deliberative and make use o ...

for some

domain-specific language A domain-specific language (DSL) is a computer language specialized to a particular application domain. This is in contrast to a general-purpose language (GPL), which is broadly applicable across domains. There are a wide variety of DSLs, ranging ...

, Greenspun's rule suggests using a widely accepted, fully featured language like Lisp. Paul Graham also highlights the satiric nature of the concept, albeit based on real issues: The rule was written sometime around 1993 by

Philip Greenspun Philip Greenspun (born September 28, 1963) is an American computer scientist, educator, early Internet entrepreneur, and pilot who was a pioneer in developing online communities like photo.net. Biography Greenspun was born on September 28, 1 ...

. Although it is known as his tenth rule, this is a misnomer. There are in fact no preceding rules, only the tenth. The reason for this according to Greenspun:

Hacker A hacker is a person skilled in information technology who achieves goals and solves problems by non-standard means. The term has become associated in popular culture with a security hackersomeone with knowledge of bug (computing), bugs or exp ...

Robert Morris later declared a

corollary In mathematics and logic, a corollary ( , ) is a theorem of less importance which can be readily deduced from a previous, more notable statement. A corollary could, for instance, be a proposition which is incidentally proved while proving another ...

, which clarifies the set of "sufficiently complicated" programs to which the rule applies: This corollary jokingly refers to the fact that many Common Lisp implementations (especially those available in the early 1990s) depend upon a low-level core of compiled C, which sidesteps the issue of

bootstrapping In general, bootstrapping usually refers to a self-starting process that is supposed to continue or grow without external input. Many analytical techniques are often called bootstrap methods in reference to their self-starting or self-supporting ...

but may itself be somewhat variable in quality, at least compared to a cleanly self-hosting Common Lisp.

References

{{Lisp programming language Computer architecture statements Lisp (programming language) 1993 neologisms Programming language folklore Computer programming folklore Software engineering folklore C (programming language) software Fortran software Aphorisms

Overview

See also

References