COWSEL (COntrolled Working SpacE Language) is a programming language designed between 1964 and 1966 by Robin Popplestone. It was based on an 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.
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
Note that keywords were also underlined in the original printouts. Popplestone used a Flexowriter with underscoring for syntax highlighting.
Edited: 2021-06-18 18:12:30