1. New Programming Language. IBM's original (temporary) name
for PL/I, changed due to conflict with England's "National
Physical Laboratory." MPL and MPPL were considered before
settling on PL/I. Sammet 1969, p.542.
2. 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
comprehensions. NPL eventually evolved into Hope but lost
set comprehensions which were called list comprehensions in
later functional languages.
[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.]
3. NonProcedural Language. A relational database language
developed by T.D. Truitt et al in 1980 for Apple II and
MS-DOS.
["An Introduction to Nonprocedural Languages Using NPL",
T.D. Truitt et al, McGraw-Hill 1983].
