Copyright	(c) Justin Le 2019
License	BSD3
Maintainer	justin@jle.im
Stability	experimental
Portability	non-portable
Safe Haskell	Safe-Inferred
Language	Haskell2010

Data.Functor.Contravariant.Decide

Description

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

Synopsis

class Contravariant f => Decide f where
- decide :: (a -> Either b c) -> f b -> f c -> f a
decided :: Decide f => f b -> f c -> f (Either b c)

Documentation

class Contravariant f => Decide f where Source #

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 Source #

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

Instances

Instances details

Decide SettableStateVar Source #
Instance details Defined in Data.Functor.Contravariant.Decide Methods decide :: (a -> Either b c) -> SettableStateVar b -> SettableStateVar c -> SettableStateVar a Source #
Decide Comparison Source #
Instance details Defined in Data.Functor.Contravariant.Decide Methods decide :: (a -> Either b c) -> Comparison b -> Comparison c -> Comparison a Source #
Decide Equivalence Source #
Instance details Defined in Data.Functor.Contravariant.Decide Methods decide :: (a -> Either b c) -> Equivalence b -> Equivalence c -> Equivalence a Source #
Decide Predicate Source #
Instance details Defined in Data.Functor.Contravariant.Decide Methods decide :: (a -> Either b c) -> Predicate b -> Predicate c -> Predicate a Source #
FreeOf Decide Dec1 Source #	Since: 0.3.0.0
Instance details Defined in Data.HFunctor.Final Associated Types type FreeFunctorBy Dec1 :: (Type -> Type) -> Constraint Source # Methods fromFree :: forall (f :: Type -> Type). Dec1 f ~> Final Decide f Source # toFree :: forall (f :: Type -> Type). FreeFunctorBy Dec1 f => Final Decide f ~> Dec1 f Source #
Decide (Op r) Source #	Unlike `Decidable`, requires no constraint on `r`
Instance details Defined in Data.Functor.Contravariant.Decide Methods decide :: (a -> Either b c) -> Op r b -> Op r c -> Op r a Source #
Decide (Proxy :: Type -> Type) Source #
Instance details Defined in Data.Functor.Contravariant.Decide Methods decide :: (a -> Either b c) -> Proxy b -> Proxy c -> Proxy a Source #
Decide (U1 :: Type -> Type) Source #
Instance details Defined in Data.Functor.Contravariant.Decide Methods decide :: (a -> Either b c) -> U1 b -> U1 c -> U1 a Source #
Decide (V1 :: Type -> Type) Source #
Instance details Defined in Data.Functor.Contravariant.Decide Methods decide :: (a -> Either b c) -> V1 b -> V1 c -> V1 a Source #
Decide (Dec f) Source #
Instance details Defined in Data.Functor.Contravariant.Divisible.Free Methods decide :: (a -> Either b c) -> Dec f b -> Dec f c -> Dec f a Source #
Decide (Dec1 f) Source #
Instance details Defined in Data.Functor.Contravariant.Divisible.Free Methods decide :: (a -> Either b c) -> Dec1 f b -> Dec1 f c -> Dec1 f a Source #
Divise m => Decide (ListT m) Source #
Instance details Defined in Data.Functor.Contravariant.Decide Methods decide :: (a -> Either b c) -> ListT m b -> ListT m c -> ListT m a Source #
Divise m => Decide (MaybeT m) Source #
Instance details Defined in Data.Functor.Contravariant.Decide Methods decide :: (a -> Either b c) -> MaybeT m b -> MaybeT m c -> MaybeT m a Source #
Decide f => Decide (Alt f) Source #
Instance details Defined in Data.Functor.Contravariant.Decide Methods decide :: (a -> Either b c) -> Alt f b -> Alt f c -> Alt f a Source #
Decide f => Decide (Rec1 f) Source #
Instance details Defined in Data.Functor.Contravariant.Decide Methods decide :: (a -> Either b c) -> Rec1 f b -> Rec1 f c -> Rec1 f a Source #
Decide f => Decide (ListF f) Source #	Since: 0.3.0.0
Instance details Defined in Control.Applicative.ListF Methods decide :: (a -> Either b c) -> ListF f b -> ListF f c -> ListF f a Source #
Decide f => Decide (MaybeF f) Source #	Since: 0.3.3.0
Instance details Defined in Control.Applicative.ListF Methods decide :: (a -> Either b c) -> MaybeF f b -> MaybeF f c -> MaybeF f a Source #
Decide f => Decide (NonEmptyF f) Source #	Since: 0.3.0.0
Instance details Defined in Control.Applicative.ListF Methods decide :: (a -> Either b c) -> NonEmptyF f b -> NonEmptyF f c -> NonEmptyF f a Source #
Decide f => Decide (Step f) Source #	Since: 0.3.0.0
Instance details Defined in Control.Applicative.Step Methods decide :: (a -> Either b c) -> Step f b -> Step f c -> Step f a Source #
Decidable f => Decide (WrappedDivisible f) Source #
Instance details Defined in Data.Functor.Contravariant.Decide Methods decide :: (a -> Either b c) -> WrappedDivisible f b -> WrappedDivisible f c -> WrappedDivisible f a Source #
Semigroup w => Decide (AltConst w :: Type -> Type) Source #	Unlike for `Const`, this is possible because there is no `Decidable` instance to complicate things.
Instance details Defined in Data.HFunctor.Interpret Methods decide :: (a -> Either b c) -> AltConst w b -> AltConst w c -> AltConst w a Source #
Decide f => Decide (Backwards f) Source #
Instance details Defined in Data.Functor.Contravariant.Decide Methods decide :: (a -> Either b c) -> Backwards f b -> Backwards f c -> Backwards f a Source #
Decide f => Decide (IdentityT f) Source #
Instance details Defined in Data.Functor.Contravariant.Decide Methods decide :: (a -> Either b c) -> IdentityT f b -> IdentityT f c -> IdentityT f a Source #
Decide m => Decide (ReaderT r m) Source #
Instance details Defined in Data.Functor.Contravariant.Decide Methods decide :: (a -> Either b c) -> ReaderT r m b -> ReaderT r m c -> ReaderT r m a Source #
Decide m => Decide (StateT s m) Source #
Instance details Defined in Data.Functor.Contravariant.Decide Methods decide :: (a -> Either b c) -> StateT s m b -> StateT s m c -> StateT s m a Source #
Decide m => Decide (StateT s m) Source #
Instance details Defined in Data.Functor.Contravariant.Decide Methods decide :: (a -> Either b c) -> StateT s m b -> StateT s m c -> StateT s m a Source #
Decide m => Decide (WriterT w m) Source #
Instance details Defined in Data.Functor.Contravariant.Decide Methods decide :: (a -> Either b c) -> WriterT w m b -> WriterT w m c -> WriterT w m a Source #
Decide m => Decide (WriterT w m) Source #
Instance details Defined in Data.Functor.Contravariant.Decide Methods decide :: (a -> Either b c) -> WriterT w m b -> WriterT w m c -> WriterT w m a Source #
Decide f => Decide (Reverse f) Source #
Instance details Defined in Data.Functor.Contravariant.Decide Methods decide :: (a -> Either b c) -> Reverse f b -> Reverse f c -> Reverse f a Source #
Contravariant (Final Decide f) Source #	Since: 0.3.0.0
Instance details 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) Source #
Instance details Defined in Data.Functor.Contravariant.Decide Methods decide :: (a -> Either b c) -> Product f g b -> Product f g c -> Product f g a Source #
(Decide f, Decide g) => Decide (f :*: g) Source #
Instance details Defined in Data.Functor.Contravariant.Decide Methods decide :: (a -> Either b c) -> (f :: g) b -> (f :: g) c -> (f :*: g) a Source #
Decide (ProxyF f :: Type -> Type) Source #	Since: 0.3.0.0
Instance details Defined in Data.HFunctor Methods decide :: (a -> Either b c) -> ProxyF f b -> ProxyF f c -> ProxyF f a Source #
Contravariant f => Decide (Chain1 Night f) Source #	`Chain1 Night` is the free "semigroup in the semigroupoidal category of endofunctors enriched by `Night`" --- aka, the free `Decide`. Since: 0.3.0.0
Instance details Defined in Data.HFunctor.Chain Methods decide :: (a -> Either b c) -> Chain1 Night f b -> Chain1 Night f c -> Chain1 Night f a Source #
Decide (Final Decidable f) Source #	Since: 0.3.0.0
Instance details Defined in Data.HFunctor.Final Methods decide :: (a -> Either b c) -> Final Decidable f b -> Final Decidable f c -> Final Decidable f a Source #
Decide (Final Conclude f) Source #	Since: 0.3.0.0
Instance details Defined in Data.HFunctor.Final Methods decide :: (a -> Either b c) -> Final Conclude f b -> Final Conclude f c -> Final Conclude f a Source #
Decide (Final Decide f) Source #	Since: 0.3.0.0
Instance details Defined in Data.HFunctor.Final Methods decide :: (a -> Either b c) -> Final Decide f b -> Final Decide f c -> Final Decide f a Source #
(Apply f, Decide g) => Decide (Compose f g) Source #	Unlike `Decidable`, requires only `Apply` on `f`.
Instance details Defined in Data.Functor.Contravariant.Decide Methods decide :: (a -> Either b c) -> Compose f g b -> Compose f g c -> Compose f g a Source #
(Apply f, Decide g) => Decide (f :.: g) Source #	Unlike `Decidable`, requires only `Apply` on `f`.
Instance details Defined in Data.Functor.Contravariant.Decide Methods decide :: (a -> Either b c) -> (f :.: g) b -> (f :.: g) c -> (f :.: g) a Source #
Decide f => Decide (M1 i c f) Source #
Instance details 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 Source #
Decide m => Decide (RWST r w s m) Source #
Instance details 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 Source #
Decide m => Decide (RWST r w s m) Source #
Instance details 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 Source #
Decide (Chain Night Not f) Source #	Since: 0.3.0.0
Instance details 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 Source #

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

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.

Key	Shortcut
s	Open this search box
esc	Close this search box
↓,ctrl + j	Move down in search results
↑,ctrl + k	Move up in search results
↵	Go to active search result