control-monad-free-0.5: Free monads and monad transformers Source code Contents Index

Control.Monad.Free

Contents Free Monads Free Monad Transformers Translate between Free monad and Free monad transformer computations

Synopsis

module Control.Monad class (Functor f, Monad m) => MonadFree f m where free :: m a -> m (Either a (f (m a))) wrap :: f (m a) -> m a data Free f a = Impure (f (Free f a)) | Pure a isPure :: Free t t1 -> Bool isImpure :: Free t t1 -> Bool foldFree :: Functor f => (a -> b) -> (f b -> b) -> Free f a -> b foldFreeM :: (Functor f, Traversable f, Monad m) => (a -> m b) -> (f b -> m b) -> Free f a -> m b evalFree :: (a -> b) -> (f (Free f a) -> b) -> Free f a -> b mapFree :: (Functor f, Functor g) => (forall a. f a -> g a) -> Free f a -> Free g a mapFreeM :: (Traversable f, Functor g, Monad m) => (forall a. f a -> m (g a)) -> Free f a -> m (Free g a) newtype FreeT f m a = FreeT { unFreeT :: m (Either a (f (FreeT f m a))) } foldFreeT :: (Traversable f, Monad m) => (a -> m b) -> (f b -> m b) -> FreeT f m a -> m b foldFreeT' :: (Traversable f, Monad m) => (a -> b) -> (f b -> b) -> FreeT f m a -> m b mapFreeT :: (Functor f, Functor m) => (forall a. m a -> m' a) -> FreeT f m a -> FreeT f m' a trans :: (Functor f, Monad m) => Free f a -> FreeT f m a trans' :: (Functor f, Monad m) => m (Free f a) -> FreeT f m a untrans :: (Traversable f, Monad m) => FreeT f m a -> m (Free f a) liftFree :: (Functor f, Monad m) => (a -> Free f b) -> a -> FreeT f m b

Documentation

module Control.Monad

Free Monads

class (Functor f, Monad m) => MonadFree f m where Source

This type class generalizes over encodings of Free Monads. Methods free Source :: => m a Opens a computation and allows to observe the side effects -> m (Either a (f (m a))) wrap Source :: => f (m a) Wraps a side effect into a monadic computation -> m a Instances Functor f => MonadFree f (Free f) Functor f => MonadFree f (C (Free f)) (Functor f, Monad m) => MonadFree f (FreeT f m)

data Free f a Source

Constructors Impure (f (Free f a)) Pure a Instances Functor f => MonadFree f (Free f) Functor f => MonadFree f (C (Free f)) Functor f => Monad (Free f) Functor f => Functor (Free f) (Functor f, Foldable f) => Foldable (Free f) Traversable f => Traversable (Free f) (Eq a, Eq (f (Free f a))) => Eq (Free f a) (Ord a, Ord (f (Free f a))) => Ord (Free f a) (Show a, Show (f (Free f a))) => Show (Free f a)

isPure :: Free t t1 -> Bool Source

isImpure :: Free t t1 -> Bool Source

foldFree :: Functor f => (a -> b) -> (f b -> b) -> Free f a -> b Source

foldFreeM :: (Functor f, Traversable f, Monad m) => (a -> m b) -> (f b -> m b) -> Free f a -> m b Source

evalFree :: (a -> b) -> (f (Free f a) -> b) -> Free f a -> b Source

mapFree :: (Functor f, Functor g) => (forall a. f a -> g a) -> Free f a -> Free g a Source

mapFreeM :: (Traversable f, Functor g, Monad m) => (forall a. f a -> m (g a)) -> Free f a -> m (Free g a) Source

Free Monad Transformers

newtype FreeT f m a Source

Constructors FreeT unFreeT :: m (Either a (f (FreeT f m a))) Instances (Functor f, Monad m) => MonadFree f (FreeT f m) Functor f => MonadTrans (FreeT f) (Functor f, Monad m) => Monad (FreeT f m) (Functor f, Functor m) => Functor (FreeT f m) (Traversable m, Traversable f) => Foldable (FreeT f m) (Traversable m, Traversable f) => Traversable (FreeT f m)

foldFreeT :: (Traversable f, Monad m) => (a -> m b) -> (f b -> m b) -> FreeT f m a -> m b Source

foldFreeT' :: (Traversable f, Monad m) => (a -> b) -> (f b -> b) -> FreeT f m a -> m b Source

mapFreeT :: (Functor f, Functor m) => (forall a. m a -> m' a) -> FreeT f m a -> FreeT f m' a Source

Translate between Free monad and Free monad transformer computations

trans :: (Functor f, Monad m) => Free f a -> FreeT f m a Source

trans' :: (Functor f, Monad m) => m (Free f a) -> FreeT f m a Source

untrans :: (Traversable f, Monad m) => FreeT f m a -> m (Free f a) Source

liftFree :: (Functor f, Monad m) => (a -> Free f b) -> a -> FreeT f m b Source

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