An expression in a functional language denoting the results of some operation on (selected) elements of one or more lists. An example in Haskell:
[ (x,y) | x This returns all pairs of numbers (x,y) where x and y are elements of the list 1, 2, …, 10, y A list comprehension is simply “syntactic sugar” for a combination of applications of the functions, concat, map and filter. For instance the above example could be written:
filter p (concat (map (\ x -> map (\ y -> (x,y)) [1..x]) [1..6])) where p (x,y) = x+y According to a note by Rishiyur Nikhil , (August 1992), the term itself seems to have been coined by Phil Wadler circa 1983-5, although the programming construct itself goes back much further (most likely Jack Schwartz and the SETL language).
The term “list comprehension” appears in the references below.
The earliest reference to the notation is in Rod Burstall and John Darlington’s description of their language, NPL.
David Turner subsequently adopted this notation in his languages SASL, KRC and Miranda, where he has called them “ZF expressions”, set abstractions and list abstractions (in his 1985 FPCA paper [Miranda: A Non-Strict Functional Language with Polymorphic Types]).
[“The OL Manual” Philip Wadler, Quentin Miller and Martin Raskovsky, probably 1983-1985].
[“How to Replace Failure by a List of Successes” FPCA September 1985, Nancy, France, pp. 113-146].
[lis-tid] /ˈlɪs tɪd/ adjective 1. (of a security) admitted to trading privileges on a stock exchange. 2. (of a telephone number or telephone subscriber) represented in a telephone directory. [list] /lɪst/ noun 1. a series of names or other items written or printed together in a meaningful grouping or sequence so as to constitute a […]
- Listed building
noun 1. (in Britain) a building officially recognized as having special historical or architectural interest and therefore protected from demolition or alteration
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noun 1. (stock exchange) a company whose shares are quoted on the main market of the London Stock Exchange
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noun 1. (stock exchange) a security that is quoted on the main market of the London Stock Exchange and appears in its Official List of Securities Compare Third Market, Unlisted Securities Market