Data.Type.Disjunction

Two type combinators for working with disjunctions: A branch combinator '(:+:)', and a choice combinator '(:|:)'.

These are analogous to '(+++)' and '(|||)' from Arrow, respectively.

Documentation

data f :+: g :: k -> * where infixr 4

Constructors

L :: !(f a) -> (f :+: g) a

R :: !(g a) -> (f :+: g) a

Instances

HBifunctor k k k ((:+:) k)

HTraversable k k ((:+:) k f)

HFoldable k k ((:+:) k f)

HFunctor k k ((:+:) k f)

(Witness p q (f a), Witness p q (g a)) => Witness p q ((:+:) k f g a)

type WitnessC p q ((:+:) k f g a) = (Witness p q (f a), Witness p q (g a))

(>+<) :: (f a -> r) -> (g a -> r) -> (f :+: g) a -> r infixr 2

data f :|: g :: Either k l -> * where infixr 4

Constructors

L' :: !(f a) -> (f :|: g) (Left a)

R' :: !(g b) -> (f :|: g) (Right b)

Instances

HBifunctor k k (Either k k) ((:|:) k k)

Witness p q (g b) => Witness p q ((:|:) k k f g (Right k k b))

Witness p q (f a) => Witness p q ((:|:) k k f g (Left k k a))

HTraversable k (Either k k) ((:|:) k k f)

HFoldable k (Either k k) ((:|:) k k f)

HFunctor k (Either k k) ((:|:) k k f)

Known k1 g b => Known (Either k k) ((:|:) k k f g) (Right k k b)

Known k1 f a => Known (Either k k) ((:|:) k k f g) (Left k k a)

type WitnessC p q ((:|:) k k1 f g (Right k k1 b)) = Witness p q (g b)

type WitnessC p q ((:|:) k1 k f g (Left k1 k a)) = Witness p q (f a)

type KnownC (Either k k1) ((:|:) k k1 f g) (Right k k1 b) = Known k1 g b

type KnownC (Either k1 k) ((:|:) k1 k f g) (Left k1 k a) = Known k1 f a

(>|<) :: (forall a. (e ~ Left a) => f a -> r) -> (forall b. (e ~ Right b) => g b -> r) -> (f :|: g) e -> r infixr 2