COWSEL (COntrolled Working SpacE Language) is a programming language designed between 1964 and 1966 by Robin Popplestone . It was based on a RPN form of Lisp combined with some ideas from CPL.

COWSEL was initially implemented on a Ferranti Pegasus computer at the University of Leeds and on a Stantec Zebra at the Bradford Institute of Technology ; later, Rod Burstall implemented it on an Elliot 4120 at the University of Edinburgh.

COWSEL was renamed POP-1 during the summer of 1966 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

Reference

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

External link

• —The Early Development of POP  (BROKEN)