Just package:skeletest

just :: forall (m :: Type -> Type) a . Monad m => Predicate m a -> Predicate m (Maybe a)
skeletest Skeletest.Internal.Predicate Skeletest.Predicate
A predicate checking if the input is Just, wrapping a value matching the given predicate. 
>>> Just 1 `shouldSatisfy` P.just (P.gt 0)
adjustNested :: (Ord k, Foldable t, IsList (t a)) => (t a -> t a) -> k -> Map k (t a) -> Map k (t a)
skeletest Skeletest.Internal.Utils.Map
Same as adjust, except defaulting to an empty structure if it doesn't exist, and deleting the key if the adjusted value is empty.