filter -package:base -package:aeson is:exact -package:bytestring package:base-compat

filter p xs removes any elements from xs that do not satisfy p.
filter, applied to a predicate and a list, returns the list of those elements that satisfy the predicate; i.e.,
filter p xs = [ x | x <- xs, p x]
>>> filter odd [1, 2, 3]
[1,3]