Safe Haskell	None
Language	Haskell2010

Servant.API.UVerb.Union

Description

Type-level code for implementing and using UVerb . Heavily inspired by world-peace .

Synopsis

type IsMember (a :: u) (as :: [u]) = ( Unique as, CheckElemIsMember a as, UElem a as)
type family Unique xs :: Constraint where ...
type Union = NS I
inject :: UElem x xs => f x -> NS f xs
eject :: UElem x xs => NS f xs -> Maybe (f x)
foldMapUnion :: forall (c :: * -> Constraint ) (a :: *) (as :: [*]). All c as => Proxy c -> ( forall x. c x => x -> a) -> Union as -> a
matchUnion :: forall (a :: *) (as :: [*]). IsMember a as => Union as -> Maybe a

Documentation

type IsMember (a :: u) (as :: [u]) = ( Unique as, CheckElemIsMember a as, UElem a as) Source #

type family Unique xs :: Constraint where ... Source #

Equations

Unique xs = If (Nubbed xs == ' True ) (() :: Constraint ) ( TypeError (DuplicateElementError xs))

type Union = NS I Source #

inject :: UElem x xs => f x -> NS f xs Source #

eject :: UElem x xs => NS f xs -> Maybe (f x) Source #

foldMapUnion :: forall (c :: * -> Constraint ) (a :: *) (as :: [*]). All c as => Proxy c -> ( forall x. c x => x -> a) -> Union as -> a Source #

Convenience function to apply a function to an unknown union element using a type class. All elements of the union must have instances in the type class, and the function is applied unconditionally.