COWSEL (COntrolled Working SpacE Language) is a

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 ...

designed between 1964 and 1966 by Robin Popplestone. It was based on an

reverse Polish notation Reverse Polish notation (RPN), also known as reverse Łukasiewicz notation, Polish postfix notation or simply postfix notation, is a mathematical notation in which operators ''follow'' their operands, in contrast to prefix or Polish notation ...

(RPN) form of the 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, ...

, combined with some ideas from

Combined Programming Language CPL (Combined Programming Language) is a multi-paradigm programming language developed in the early 1960s. It is an early ancestor of the C language via the BCPL and B languages. Design CPL was developed initially at the Mathematical Laborato ...

(CPL). COWSEL was initially implemented on a Ferranti Pegasus computer at the

University of Leeds The University of Leeds is a public research university in Leeds, West Yorkshire, England. It was established in 1874 as the Yorkshire College of Science. In 1884, it merged with the Leeds School of Medicine (established 1831) and was renamed Y ...

and on a Stantec Zebra at the Bradford Institute of Technology. Later,

Rod Burstall Rodney Martineau Burstall (11 November 1934 – 13 February 2025) was a British computer scientist who was one of four founders of the Laboratory for Foundations of Computer Science at the University of Edinburgh. Biography Burstall studied p ...

implemented it on an Elliot 4120 at the

University of Edinburgh The University of Edinburgh (, ; abbreviated as ''Edin.'' in Post-nominal letters, post-nominals) is a Public university, public research university based in Edinburgh, Scotland. Founded by the City of Edinburgh Council, town council under th ...

. COWSEL was renamed POP-1 in 1966, during summer, and development continued under that name from then on.

Example code

function member lambda x y comment Is x a member of list y; define y atom then *0 end y hd x equal then *1 end y tl -> y repeat up

Reserved word In a programming language, a reserved word (sometimes known as a reserved identifier) is a word that cannot be used by a programmer as an identifier, such as the name of a variable, function, or label – it is "reserved from use". In brief, an '' ...

s (keywords) were also underlined in the original printouts. Popplestone performed

syntax highlighting Syntax highlighting is a feature of text editors that is used for programming language, programming, scripting language, scripting, or markup language, markup languages, such as HTML. The feature displays text, especially source code, in differe ...

by using underscoring on a Friden Flexowriter.

References

* Technical report: EPU-R-12, U Edinburgh (Apr 1966)

External links

"The Early Development of POP" on The Encyclopedia of Computer Languages
Functional languages Lisp programming language family History of computing in the United Kingdom Programming languages created in 1964 Programming languages Science and technology in Edinburgh University of Bradford University of Edinburgh University of Leeds {{Prog-lang-stub

Example code

See also

References

External links