filter -package:base -package:unordered-containers -package:text

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, applied to a predicate and a ShortByteString, returns a ShortByteString containing those characters that satisfy the predicate.

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.

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.

Filter all elements that satisfy the predicate.

O(n) Drop all elements that do not satisfy the predicate.

Drop elements which do not satisfy the predicate

Drop elements which do not satisfy the predicate

O(n) Drop all elements that do not satisfy the predicate.

O(n) Drop all elements that do not satisfy the predicate.

O(n) Drop all elements that do not satisfy the predicate.

O(n) Drop all elements that do not satisfy the predicate.

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.

Filter the entries whose keys are missing from the other map using some Applicative action.

filterAMissing f = Merge.Lazy.traverseMaybeMissing $
\k x -> (\b -> guard b *> Just x) <$> f k x

but this should be a little faster.

Filter all keys that satisfy some predicate.

filterKeys p = filterWithKey (\k _ -> p k)

filterKeys (> 4) (fromList [(5,"a"), (3,"b")]) == singleton 5 "a"

Filter the entries whose keys are missing from the other map.

filterMissing :: (k -> x -> Bool) -> SimpleWhenMissing x x

filterMissing f = Merge.Lazy.mapMaybeMissing $ \k x -> guard (f k x) *> Just x

but this should be a little faster.

Filter all keys/values that satisfy some predicate.

filterWithKey (\k _ -> k > 4) (fromList [(5,"a"), (3,"b")]) == singleton 5 "a"

Filter the entries whose keys are missing from the other map using some Applicative action.

filterAMissing f = Merge.Lazy.traverseMaybeMissing $
\k x -> (\b -> guard b *> Just x) <$> f k x

but this should be a little faster.