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:''At least three unrelated{{for|other programming languages haveand hadconcepts theabbreviated nameas '''NPL'''.''|NPL (disambiguation)}}
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'''NPL''' wasis a [[ Functional programming|functional programming language]] with [[pattern matching]] designed by [[Rod Burstall ]] and [[John Darlington ]] in 1977. The language allowedallows certain sets and logic constructs to appear on the right -hand side of definitions, Ee.g. ▼'''NPL''' (possibly for '''N'''ew '''P'''rogramming '''L'''anguage) was the original name given to what would later become [[IBM]]'s [[PL/I]] programming language.
The 'NPL' name was in effect between [[March 1]] and [[November 30]], [[1964]]. The name was changed to avoid collision with the National Physical Laboratory. MPL and MPPL were considered before settling on PL/I.
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▲'''NPL''' was a [[functional language]] with [[pattern matching]] designed by Rod Burstall and John Darlington in 1977. The language allowed certain sets and logic constructs to appear on the right hand side of definitions, E.g.
setofeven(X) <= <:x: x in X & even(x) :>
The NPL interpreter evaluates the list of generators from left to right so conditions can mention any bound variables that occur to their left. These were known as [[set comprehensionscomprehension]]s. NPL eventually evolved into [[Hope programming language|Hope]] but lost set comprehensions, which weremade calleda reappearance in the form of [[list comprehension]]s in later functional languages.<ref name="foldoc">{{foldoc|NPL}}</ref>
''Reference: John Darlington, "Program Transformation and Synthesis: Present Capabilities", Research Report No. 77/43, Dept. of Computing and Control, Imperial College of Science and Technology, London September 1977.'' ▼
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==References==
'''NPL''' (for '''NonProcedural Language''') was a [[relational database]] language developed by T.D. Truitt et al in 1980 for [[Apple II]] and [[MS-DOS]].
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▲''Reference:* John Darlington , (1977). "Program Transformation and Synthesis: Present Capabilities" ,. Research Report No. 77/43, Dept. of Computing and Control, Imperial College of Science and Technology, London September 1977. ''
[[Category: HistoricalAcademic programming languages]] ▼''Reference: "An Introduction to Nonprocedural Languages Using NPL", T.D. Truitt et al, McGraw-Hill 1983.''
[[Category: PL/IFunctional dialectslanguages]] ▼[[Category:History of computing in the United Kingdom]]
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▲[[Category:Historical programming languages]]
▲[[Category:PL/I dialects]]
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