1. (Originally Unix, now also MS-DOS) A program that
processes an input data stream into an output data stream in
some well-defined way, and does no I/O to anywhere else except
possibly on error conditions; one designed to be used as a
stage in a pipeline (see plumbing). Compare sponge.
2. (functional programming) A higher-order function which
takes a predicate and a list and returns those elements of
the list for which the predicate is true. In Haskell:
filter p [] = []
filter p (x:xs) = if p x then x : rest else rest
where
rest = filter p xs
See also filter promotion.
[Jargon File]
Nearby terms:
film at 11 « FILO « Filtabyte « filter » filter promotion » FIMS » Finagle's Law
