In programming, the rule of least power is a design principle that "suggests choosing the least powerful omputerlanguage suitable for a given purpose". Stated alternatively, given a choice among

computer languages A computer language is a formal language used to communicate with a computer. Types of computer languages include: * Construction language – all forms of communication by which a human can specify an executable problem solution to a comput ...

, classes of which range from

descriptive In the study of language, description or descriptive linguistics is the work of objectively analyzing and describing how language is actually used (or how it was used in the past) by a speech community. François & Ponsonnet (2013). All acad ...

(or ''declarative'') to procedural, the less procedural, more descriptive the language one chooses, the more one can do with the data stored in that language. This rule is an application of the

principle of least privilege In information security, computer science, and other fields, the principle of least privilege (PoLP), also known as the principle of minimal privilege (PoMP) or the principle of least authority (PoLA), requires that in a particular abstraction la ...

to protocol design. The Rule of Least Power is an example in context of the centuries older principle known as

Occam's razor Occam's razor, Ockham's razor, or Ocham's razor ( la, novacula Occami), also known as the principle of parsimony or the law of parsimony ( la, lex parsimoniae), is the problem-solving principle that "entities should not be multiplied beyond neces ...

in philosophy. In particular, arguments for and against the Rule of Least Power are subject to the same analysis as for

Rationale

Originally proposed as an

axiom An axiom, postulate, or assumption is a statement that is taken to be true, to serve as a premise or starting point for further reasoning and arguments. The word comes from the Ancient Greek word (), meaning 'that which is thought worthy or f ...

of good design, the term is an extension of the

KISS principle KISS, an acronym for "Keep it simple, stupid!", is a design principle noted by the U.S. Navy in 1960. First seen partly in American English by at least 1938, the KISS principle states that most systems work best if they are kept simple rather tha ...

applied to choosing among a range of languages ranging from * the plainly descriptive ones (such as the content of most

database In computing, a database is an organized collection of data stored and accessed electronically. Small databases can be stored on a file system, while large databases are hosted on computer clusters or cloud storage. The design of databases sp ...

s, or

progressive enhancement Progressive enhancement is a strategy in web design that puts emphasis on web content first, allowing everyone to access the basic content and functionality of a web page, whilst users with additional browser features or faster Internet access ...

on the web), * logical languages of limited

propositional logic Propositional calculus is a branch of logic. It is also called propositional logic, statement logic, sentential calculus, sentential logic, or sometimes zeroth-order logic. It deals with propositions (which can be true or false) and relations b ...

(such as

access control list In computer security, an access-control list (ACL) is a list of permissions associated with a system resource (object). An ACL specifies which users or system processes are granted access to objects, as well as what operations are allowed on giv ...

s), *

declarative language In computer science, declarative programming is a programming paradigm—a style of building the structure and elements of computer programs—that expresses the logic of a computation without describing its control flow. Many languages that a ...

s on the verge of being

Turing-complete In computability theory, a system of data-manipulation rules (such as a computer's instruction set, a programming language, or a cellular automaton) is said to be Turing-complete or computationally universal if it can be used to simulate any Tur ...

, * those that are in fact Turing-complete though one is led not to use them that way (

XSLT XSLT (Extensible Stylesheet Language Transformations) is a language originally designed for transforming XML documents into other XML documents, or other formats such as HTML for web pages, plain text or XSL Formatting Objects, which may subseque ...

, SQL), * those that are

functional Functional may refer to: * Movements in architecture: ** Functionalism (architecture) ** Form follows function * Functional group, combination of atoms within molecules * Medical conditions without currently visible organic basis: ** Functional sy ...

and Turing-complete

general-purpose programming language In computer software, a general-purpose programming language (GPL) is a programming language for building software in a wide variety of application domains. Conversely, a domain-specific programming language is used within a specific area. For exam ...

s, to * those that are "unashamedly imperative". As explained by

Tim Berners-Lee Sir Timothy John Berners-Lee (born 8 June 1955), also known as TimBL, is an English computer scientist best known as the inventor of the World Wide Web. He is a Professorial Fellow of Computer Science at the University of Oxford and a profess ...

Computer Science in the 1960s to 80s spent a lot of effort making languages that were as powerful as possible. Nowadays we have to appreciate the reasons for picking not the most powerful solution but the least powerful. The reason for this is that the less powerful the language, the more you can do with the data stored in that language. If you write it in a simple declarative form, anyone can write a program to analyze it in many ways. The Semantic Web is an attempt, largely, to map large quantities of existing data onto a common language so that the data can be analyzed in ways never dreamed of by its creators. If, for example, a web page with weather data has RDF describing that data, a user can retrieve it as a table, perhaps average it, plot it, deduce things from it in combination with other information. At the other end of the scale is the weather information portrayed by the cunning Java applet. While this might allow a very cool user interface, it cannot be analyzed at all. The search engine finding the page will have no idea of what the data is or what it is about. The only way to find out what a Java applet means is to set it running in front of a person.

References

The Rule of Least Power

W3C The World Wide Web Consortium (W3C) is the main international standards organization for the World Wide Web. Founded in 1994 and led by Tim Berners-Lee, the consortium is made up of member organizations that maintain full-time staff working to ...

, TAG Finding 23 February 2006 * B. Carpenter, Editor: "Architectural Principles of the Internet" Internet Architecture Board, June 1996, RFC 1958 {{refend Software development philosophies Software design Programming language folklore Software engineering folklore

Rationale

See also

References