filter

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]
filter p xs removes any elements from xs that do not satisfy p.
O(n) filter, applied to a predicate and a ByteString, returns a ByteString containing those characters that satisfy the predicate.
O(n) filter, applied to a predicate and a ByteString, returns a ByteString containing those characters that satisfy the predicate.
O(n). 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
O(n). Filter all elements that satisfy some predicate.
O(n). Filter all values that satisfy the 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
The filter function takes a predicate p and a sequence xs and returns a sequence of those elements which satisfy the predicate.
O(n). Filter all elements that satisfy the predicate.
O(n) filter, applied to a predicate and a Text, returns a Text containing those characters that satisfy the predicate.
O(n) filter, applied to a predicate and a stream, returns a stream containing those characters that satisfy the predicate.
Filter all keys/values that satisfy some predicate.
O(n) Drop elements that do not satisfy the predicate
Drop elements which do not satisfy the predicate
Drop elements which do not satisfy the predicate
Drop elements which do not satisfy the predicate
O(n) Drop elements that do not satisfy the predicate
O(n) Drop elements that do not satisfy the predicate
O(n) Drop elements that do not satisfy the predicate
O(n) Drop elements that do not satisfy the predicate
O(n) Filter this map by retaining only elements which values satisfy a predicate.
O(n) Filter this set by retaining only elements satisfying a predicate.
Keep only values in the stream passing a given predicate. Subject to fusion
Keep only values in the stream passing a given predicate. Subject to fusion Since 0.3.0
(filter predicate) only forwards values that satisfy the predicate.
filter (pure True) = cat

filter (liftA2 (&&) p1 p2) = filter p1 >-> filter p2

filter f = mapMaybe (\a -> a <$ guard (f a))