Data.Functor.Contravariant.Decide

The contravariant counterpart of Alt: like Decidable, but without loss or a superclass constraint on Divisible. This is only a part of this library currently for compatibility, until it is (hopefully) merged into semigroupoids.

Since: 0.3.0.0

Documentation

class Contravariant f => Decide f where

The contravariant analogue of Alt.

If one thinks of f a as a consumer of as, then decide allows one to handle the consumption of a value by choosing to handle it via exactly one of two independent consumers. It redirects the input completely into one of two consumers.

decide takes the "decision" method and the two potential consumers, and returns the wrapped/combined consumer.

Mathematically, a functor being an instance of Decide means that it is "semgroupoidal" with respect to the contravariant "either-based" Day convolution (data EitherDay f g a = forall b c. EitherDay (f b) (g c) (a -> Either b c)). That is, it is possible to define a function (f EitherDay f) a -> f a in a way that is associative.

Methods

decide :: (a -> Either b c) -> f b -> f c -> f a

Takes the "decision" method and the two potential consumers, and returns the wrapped/combined consumer.

Instances

Decide SettableStateVar

Defined in Data.Functor.Contravariant.Decide

Methods

decide :: (a -> Either b c) -> SettableStateVar b -> SettableStateVar c -> SettableStateVar a

Decide Comparison

Defined in Data.Functor.Contravariant.Decide

Methods

decide :: (a -> Either b c) -> Comparison b -> Comparison c -> Comparison a

Decide Equivalence

Defined in Data.Functor.Contravariant.Decide

Methods

decide :: (a -> Either b c) -> Equivalence b -> Equivalence c -> Equivalence a

Decide Predicate

Defined in Data.Functor.Contravariant.Decide

Methods

decide :: (a -> Either b c) -> Predicate b -> Predicate c -> Predicate a

FreeOf Decide Dec1

Since: 0.3.0.0

Defined in Data.HFunctor.Final

Associated Types

type FreeFunctorBy Dec1 :: (Type -> Type) -> Constraint

Methods

fromFree :: forall (f :: Type -> Type). Dec1 f ~> Final Decide f

toFree :: forall (f :: Type -> Type). FreeFunctorBy Dec1 f => Final Decide f ~> Dec1 f

Decide (Op r)

Unlike Decidable, requires no constraint on r

Defined in Data.Functor.Contravariant.Decide

Methods

decide :: (a -> Either b c) -> Op r b -> Op r c -> Op r a

Decide (Proxy :: Type -> Type)

Defined in Data.Functor.Contravariant.Decide

Methods

decide :: (a -> Either b c) -> Proxy b -> Proxy c -> Proxy a

Decide (U1 :: Type -> Type)

Defined in Data.Functor.Contravariant.Decide

Methods

decide :: (a -> Either b c) -> U1 b -> U1 c -> U1 a

Decide (V1 :: Type -> Type)

Defined in Data.Functor.Contravariant.Decide

Methods

decide :: (a -> Either b c) -> V1 b -> V1 c -> V1 a

Decide (Dec f)

Defined in Data.Functor.Contravariant.Divisible.Free

Methods

decide :: (a -> Either b c) -> Dec f b -> Dec f c -> Dec f a

Decide (Dec1 f)

Defined in Data.Functor.Contravariant.Divisible.Free

Methods

decide :: (a -> Either b c) -> Dec1 f b -> Dec1 f c -> Dec1 f a

Divise m => Decide (ListT m)

Defined in Data.Functor.Contravariant.Decide

Methods

decide :: (a -> Either b c) -> ListT m b -> ListT m c -> ListT m a

Divise m => Decide (MaybeT m)

Defined in Data.Functor.Contravariant.Decide

Methods

decide :: (a -> Either b c) -> MaybeT m b -> MaybeT m c -> MaybeT m a

Decide f => Decide (Alt f)

Defined in Data.Functor.Contravariant.Decide

Methods

decide :: (a -> Either b c) -> Alt f b -> Alt f c -> Alt f a

Decide f => Decide (Rec1 f)

Defined in Data.Functor.Contravariant.Decide

Methods

decide :: (a -> Either b c) -> Rec1 f b -> Rec1 f c -> Rec1 f a

Decide f => Decide (ListF f)

Since: 0.3.0.0

Defined in Control.Applicative.ListF

Methods

decide :: (a -> Either b c) -> ListF f b -> ListF f c -> ListF f a

Decide f => Decide (MaybeF f)

Since: 0.3.3.0

Defined in Control.Applicative.ListF

Methods

decide :: (a -> Either b c) -> MaybeF f b -> MaybeF f c -> MaybeF f a

Decide f => Decide (NonEmptyF f)

Since: 0.3.0.0

Defined in Control.Applicative.ListF

Methods

decide :: (a -> Either b c) -> NonEmptyF f b -> NonEmptyF f c -> NonEmptyF f a

Decide f => Decide (Step f)

Since: 0.3.0.0

Defined in Control.Applicative.Step

Methods

decide :: (a -> Either b c) -> Step f b -> Step f c -> Step f a

Decidable f => Decide (WrappedDivisible f)

Defined in Data.Functor.Contravariant.Decide

Methods

decide :: (a -> Either b c) -> WrappedDivisible f b -> WrappedDivisible f c -> WrappedDivisible f a

Semigroup w => Decide (AltConst w :: Type -> Type)

Unlike for Const, this is possible because there is no Decidable instance to complicate things.

Defined in Data.HFunctor.Interpret

Methods

decide :: (a -> Either b c) -> AltConst w b -> AltConst w c -> AltConst w a

Decide f => Decide (Backwards f)

Defined in Data.Functor.Contravariant.Decide

Methods

decide :: (a -> Either b c) -> Backwards f b -> Backwards f c -> Backwards f a

Decide f => Decide (IdentityT f)

Defined in Data.Functor.Contravariant.Decide

Methods

decide :: (a -> Either b c) -> IdentityT f b -> IdentityT f c -> IdentityT f a

Decide m => Decide (ReaderT r m)

Defined in Data.Functor.Contravariant.Decide

Methods

decide :: (a -> Either b c) -> ReaderT r m b -> ReaderT r m c -> ReaderT r m a

Decide m => Decide (StateT s m)

Defined in Data.Functor.Contravariant.Decide

Methods

decide :: (a -> Either b c) -> StateT s m b -> StateT s m c -> StateT s m a

Decide m => Decide (StateT s m)

Defined in Data.Functor.Contravariant.Decide

Methods

decide :: (a -> Either b c) -> StateT s m b -> StateT s m c -> StateT s m a

Decide m => Decide (WriterT w m)

Defined in Data.Functor.Contravariant.Decide

Methods

decide :: (a -> Either b c) -> WriterT w m b -> WriterT w m c -> WriterT w m a

Decide m => Decide (WriterT w m)

Defined in Data.Functor.Contravariant.Decide

Methods

decide :: (a -> Either b c) -> WriterT w m b -> WriterT w m c -> WriterT w m a

Decide f => Decide (Reverse f)

Defined in Data.Functor.Contravariant.Decide

Methods

decide :: (a -> Either b c) -> Reverse f b -> Reverse f c -> Reverse f a

Contravariant (Final Decide f)

Since: 0.3.0.0

Defined in Data.HFunctor.Final

Methods

contramap :: (a' -> a) -> Final Decide f a -> Final Decide f a'

(>$) :: b -> Final Decide f b -> Final Decide f a

(Decide f, Decide g) => Decide (Product f g)

Defined in Data.Functor.Contravariant.Decide

Methods

decide :: (a -> Either b c) -> Product f g b -> Product f g c -> Product f g a

(Decide f, Decide g) => Decide (f :*: g)

Defined in Data.Functor.Contravariant.Decide

Methods

decide :: (a -> Either b c) -> (f :*: g) b -> (f :*: g) c -> (f :*: g) a

Decide (ProxyF f :: Type -> Type)

Since: 0.3.0.0

Defined in Data.HFunctor

Methods

decide :: (a -> Either b c) -> ProxyF f b -> ProxyF f c -> ProxyF f a

Contravariant f => Decide (Chain1 Night f)

Chain1 Night is the free "semigroup in the semigroupoidal category of endofunctors enriched by Night" --- aka, the free Decide.

Since: 0.3.0.0

Defined in Data.HFunctor.Chain

Methods

decide :: (a -> Either b c) -> Chain1 Night f b -> Chain1 Night f c -> Chain1 Night f a

Decide (Final Decidable f)

Since: 0.3.0.0

Defined in Data.HFunctor.Final

Methods

decide :: (a -> Either b c) -> Final Decidable f b -> Final Decidable f c -> Final Decidable f a

Decide (Final Conclude f)

Since: 0.3.0.0

Defined in Data.HFunctor.Final

Methods

decide :: (a -> Either b c) -> Final Conclude f b -> Final Conclude f c -> Final Conclude f a

Decide (Final Decide f)

Since: 0.3.0.0

Defined in Data.HFunctor.Final

Methods

decide :: (a -> Either b c) -> Final Decide f b -> Final Decide f c -> Final Decide f a

(Apply f, Decide g) => Decide (Compose f g)

Unlike Decidable, requires only Apply on f.

Defined in Data.Functor.Contravariant.Decide

Methods

decide :: (a -> Either b c) -> Compose f g b -> Compose f g c -> Compose f g a

(Apply f, Decide g) => Decide (f :.: g)

Unlike Decidable, requires only Apply on f.

Defined in Data.Functor.Contravariant.Decide

Methods

decide :: (a -> Either b c) -> (f :.: g) b -> (f :.: g) c -> (f :.: g) a

Decide f => Decide (M1 i c f)

Defined in Data.Functor.Contravariant.Decide

Methods

decide :: (a -> Either b c0) -> M1 i c f b -> M1 i c f c0 -> M1 i c f a

Decide m => Decide (RWST r w s m)

Defined in Data.Functor.Contravariant.Decide

Methods

decide :: (a -> Either b c) -> RWST r w s m b -> RWST r w s m c -> RWST r w s m a

Decide m => Decide (RWST r w s m)

Defined in Data.Functor.Contravariant.Decide

Methods

decide :: (a -> Either b c) -> RWST r w s m b -> RWST r w s m c -> RWST r w s m a

Decide (Chain Night Not f)

Since: 0.3.0.0

Defined in Data.HFunctor.Chain

Methods

decide :: (a -> Either b c) -> Chain Night Not f b -> Chain Night Not f c -> Chain Night Not f a

decided :: Decide f => f b -> f c -> f (Either b c)

For decided x y, the resulting f (Either b c) will direct Lefts to be consumed by x, and Rights to be consumed by y.