Control.Monad.EtaInverse

Eta inverses for some vernacular monads.

Documentation

class Monad f => EtaInverse f where

Methods

etaInv :: f t -> Maybe t

Instances

EtaInverse []

Defined in Control.Monad.EtaInverse

Methods

etaInv :: [t] -> Maybe t

EtaInverse Maybe

Defined in Control.Monad.EtaInverse

Methods

etaInv :: Maybe t -> Maybe t

EtaInverse Identity

Defined in Control.Monad.EtaInverse

Methods

etaInv :: Identity t -> Maybe t

(Monoid s, Eq s) => EtaInverse ((,) s)

Defined in Control.Monad.EtaInverse

Methods

etaInv :: (s, t) -> Maybe t

EtaInverse f => EtaInverse (MaybeT f)

Defined in Control.Monad.EtaInverse

Methods

etaInv :: MaybeT f t -> Maybe t

Functor f => EtaInverse (Free f)

Defined in Control.Monad.EtaInverse

Methods

etaInv :: Free f t -> Maybe t

(Functor f, EtaInverse f2) => EtaInverse (FreeT f f2)

Defined in Control.Monad.EtaInverse

Methods

etaInv :: FreeT f f2 t -> Maybe t

(Monoid s, Eq s, EtaInverse f) => EtaInverse (WriterT s f)

Defined in Control.Monad.EtaInverse

Methods

etaInv :: WriterT s f t -> Maybe t