Data.Singletons.Maybe
data family Sing a
type SMaybe z
Data.Maybetype family Maybe_ a a a :: b
type family FromJust a :: a
type family FromMaybe a a :: a
type family MaybeToList a :: [a]
type family ListToMaybe a :: Maybe a
type family CatMaybes a :: [a]
type family MapMaybe a a :: [b]