Safe Haskell	Safe
Language	Haskell2010

Monad.Fix

Synopsis

class Monad m => MonadFix (m :: * -> *) where

Documentation

class Monad m => MonadFix (m :: * -> *) where #

Monads having fixed points with a 'knot-tying' semantics. Instances of MonadFix should satisfy the following laws:

purity: mfix (return . h) = return (fix h)
left shrinking (or tightening): mfix (\x -> a >>= \y -> f x y) = a >>= \y -> mfix (\x -> f x y)
sliding: mfix (liftM h . f) = liftM h (mfix (f . h)), for strict h.
nesting: mfix (\x -> mfix (\y -> f x y)) = mfix (\x -> f x x)

This class is used in the translation of the recursive do notation supported by GHC and Hugs.

Minimal complete definition

mfix

Methods

mfix :: (a -> m a) -> m a #

The fixed point of a monadic computation. mfix f executes the action f only once, with the eventual output fed back as the input. Hence f should not be strict, for then mfix f would diverge.

Instances

MonadFix []	Since: base-2.1
Instance details Defined in Control.Monad.Fix Methods mfix :: (a -> [a]) -> [a] #
MonadFix Maybe	Since: base-2.1
Instance details Defined in Control.Monad.Fix Methods mfix :: (a -> Maybe a) -> Maybe a #
MonadFix IO	Since: base-2.1
Instance details Defined in Control.Monad.Fix Methods mfix :: (a -> IO a) -> IO a #
MonadFix Par1	Since: base-4.9.0.0
Instance details Defined in Control.Monad.Fix Methods mfix :: (a -> Par1 a) -> Par1 a #
MonadFix Min	Since: base-4.9.0.0
Instance details Defined in Data.Semigroup Methods mfix :: (a -> Min a) -> Min a #
MonadFix Max	Since: base-4.9.0.0
Instance details Defined in Data.Semigroup Methods mfix :: (a -> Max a) -> Max a #
MonadFix First	Since: base-4.9.0.0
Instance details Defined in Data.Semigroup Methods mfix :: (a -> First a) -> First a #
MonadFix Last	Since: base-4.9.0.0
Instance details Defined in Data.Semigroup Methods mfix :: (a -> Last a) -> Last a #
MonadFix Option	Since: base-4.9.0.0
Instance details Defined in Data.Semigroup Methods mfix :: (a -> Option a) -> Option a #
MonadFix Identity	Since: base-4.8.0.0
Instance details Defined in Data.Functor.Identity Methods mfix :: (a -> Identity a) -> Identity a #
MonadFix First	Since: base-4.8.0.0
Instance details Defined in Control.Monad.Fix Methods mfix :: (a -> First a) -> First a #
MonadFix Last	Since: base-4.8.0.0
Instance details Defined in Control.Monad.Fix Methods mfix :: (a -> Last a) -> Last a #
MonadFix Dual	Since: base-4.8.0.0
Instance details Defined in Control.Monad.Fix Methods mfix :: (a -> Dual a) -> Dual a #
MonadFix Sum	Since: base-4.8.0.0
Instance details Defined in Control.Monad.Fix Methods mfix :: (a -> Sum a) -> Sum a #
MonadFix Product	Since: base-4.8.0.0
Instance details Defined in Control.Monad.Fix Methods mfix :: (a -> Product a) -> Product a #
MonadFix NonEmpty	Since: base-4.9.0.0
Instance details Defined in Control.Monad.Fix Methods mfix :: (a -> NonEmpty a) -> NonEmpty a #
MonadFix Tree	Since: containers-0.5.11
Instance details Defined in Data.Tree Methods mfix :: (a -> Tree a) -> Tree a #
MonadFix Seq	Since: containers-0.5.11
Instance details Defined in Data.Sequence.Internal Methods mfix :: (a -> Seq a) -> Seq a #
MonadFix Eval
Instance details Defined in Control.Parallel.Strategies Methods mfix :: (a -> Eval a) -> Eval a #
MonadFix SmallArray
Instance details Defined in Data.Primitive.SmallArray Methods mfix :: (a -> SmallArray a) -> SmallArray a #
MonadFix Array
Instance details Defined in Data.Primitive.Array Methods mfix :: (a -> Array a) -> Array a #
MonadFix Moment
Instance details Defined in Reactive.Banana.Types Methods mfix :: (a -> Moment a) -> Moment a #
MonadFix MomentIO
Instance details Defined in Reactive.Banana.Types Methods mfix :: (a -> MomentIO a) -> MomentIO a #
MonadFix Element
Instance details Defined in Control.Concurrent.Chan.Unagi.NoBlocking.Types Methods mfix :: (a -> Element a) -> Element a #
MonadFix (Either e)	Since: base-4.3.0.0
Instance details Defined in Control.Monad.Fix Methods mfix :: (a -> Either e a) -> Either e a #
MonadFix (ST s)	Since: base-2.1
Instance details Defined in Control.Monad.Fix Methods mfix :: (a -> ST s a) -> ST s a #
MonadFix (Grammar r)
Instance details Defined in Text.Earley.Grammar Methods mfix :: (a -> Grammar r a) -> Grammar r a #
MonadFix m => MonadFix (MaybeT m)
Instance details Defined in Control.Monad.Trans.Maybe Methods mfix :: (a -> MaybeT m a) -> MaybeT m a #
Functor f => MonadFix (Free f)
Instance details Defined in Control.Monad.Free Methods mfix :: (a -> Free f a) -> Free f a #
MonadFix m => MonadFix (Yoneda m)
Instance details Defined in Data.Functor.Yoneda Methods mfix :: (a -> Yoneda m a) -> Yoneda m a #
MonadFix f => MonadFix (Rec1 f)	Since: base-4.9.0.0
Instance details Defined in Control.Monad.Fix Methods mfix :: (a -> Rec1 f a) -> Rec1 f a #
MonadFix f => MonadFix (Alt f)	Since: base-4.8.0.0
Instance details Defined in Control.Monad.Fix Methods mfix :: (a -> Alt f a) -> Alt f a #
MonadFix m => MonadFix (IdentityT m)
Instance details Defined in Control.Monad.Trans.Identity Methods mfix :: (a -> IdentityT m a) -> IdentityT m a #
MonadFix m => MonadFix (ExceptT e m)
Instance details Defined in Control.Monad.Trans.Except Methods mfix :: (a -> ExceptT e m a) -> ExceptT e m a #
(MonadFix m, Error e) => MonadFix (ErrorT e m)
Instance details Defined in Control.Monad.Trans.Error Methods mfix :: (a -> ErrorT e m a) -> ErrorT e m a #
MonadFix (Indexed i a)
Instance details Defined in Control.Lens.Internal.Indexed Methods mfix :: (a0 -> Indexed i a a0) -> Indexed i a a0 #
MonadFix m => MonadFix (StateT s m)
Instance details Defined in Control.Monad.Trans.State.Lazy Methods mfix :: (a -> StateT s m a) -> StateT s m a #
MonadFix (STE e s)
Instance details Defined in Control.Monad.STE.Internal Methods mfix :: (a -> STE e s a) -> STE e s a #
MonadFix m => MonadFix (StateT s m)
Instance details Defined in Control.Monad.Trans.State.Strict Methods mfix :: (a -> StateT s m a) -> StateT s m a #
MonadFix m => MonadFix (WriterT w m)
Instance details Defined in Control.Monad.Trans.Writer.CPS.Internal Methods mfix :: (a -> WriterT w m a) -> WriterT w m a #
MonadFix ((->) r :: * -> *)	Since: base-2.1
Instance details Defined in Control.Monad.Fix Methods mfix :: (a -> r -> a) -> r -> a #
(MonadFix f, MonadFix g) => MonadFix (f :*: g)	Since: base-4.9.0.0
Instance details Defined in Control.Monad.Fix Methods mfix :: (a -> (f :: g) a) -> (f :: g) a #
(MonadFix f, MonadFix g) => MonadFix (Product f g)	Since: base-4.9.0.0
Instance details Defined in Data.Functor.Product Methods mfix :: (a -> Product f g a) -> Product f g a #
MonadFix m => MonadFix (ReaderT r m)
Instance details Defined in Control.Monad.Trans.Reader Methods mfix :: (a -> ReaderT r m a) -> ReaderT r m a #
(Stream s, MonadFix m) => MonadFix (ParsecT e s m)	Since: megaparsec-6.0.0
Instance details Defined in Text.Megaparsec.Internal Methods mfix :: (a -> ParsecT e s m a) -> ParsecT e s m a #
MonadFix f => MonadFix (M1 i c f)	Since: base-4.9.0.0
Instance details Defined in Control.Monad.Fix Methods mfix :: (a -> M1 i c f a) -> M1 i c f a #