typelevel-1.2.3: Useful type level operations (type families and related operators).

Safe HaskellNone
LanguageHaskell2010

Type.Maybe

Documentation

type family IsJust a where ... Source #

Equations

IsJust (Just a) = True 
IsJust a = False 

type family CatMaybes (lst :: [Maybe k]) :: [k] where ... Source #

Equations

CatMaybes '[] = '[] 
CatMaybes (Just a ': ms) = a ': CatMaybes ms 
CatMaybes (Nothing ': ms) = CatMaybes ms 

type family FromJust (m :: Maybe k) :: k where ... Source #

Equations

FromJust (Just a) = a