COWSEL

{{Short description|Programming language}}

{{One source|date=March 2024}}

{{Use dmy dates|date=March 2024}}

{{Use British English|date=March 2024}}

{{Infobox programming language

| name = COWSEL, POP-1

| logo =

| logo caption =

| screenshot =

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| sampleCode =

| paradigm = Multi-paradigm: structured, reflective, procedural

| family = Lisp: POP

| designers = Robin Popplestone, Rod Burstall

| developers = University of Leeds, Bradford Institute of Technology, University of Edinburgh

| released = {{Start date and age|1964}}

| latest release version =

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| typing = dynamic

| memory management =

| scope =

| programming language = assembly

| platform = Ferranti Pegasus, Stantec Zebra, Elliot 4120

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| license = Proprietary

| file ext =

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| influenced by = CPL, Lisp

| influenced = POP-2

}}

COWSEL (COntrolled Working SpacE Language) is a programming language designed between 1964 and 1966 by Robin Popplestone. It was based on an reverse Polish notation (RPN) form of the language Lisp, combined with some ideas from Combined Programming Language (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 in 1966, during summer, and development continued under that name from then on.