filter -package:base -package:pipes -package:Cabal -package:conduit -is:exact package:ghc is:exact

Filter all values that satisfy some predicate.

filter (> "a") (fromList [(5,"a"), (3,"b")]) == singleton 3 "b"
filter (> "x") (fromList [(5,"a"), (3,"b")]) == empty
filter (< "a") (fromList [(5,"a"), (3,"b")]) == empty

Filter all elements that satisfy some predicate.