Control.Monad.Sharing.FirstOrder

This library provides an interface to monads that support explicit sharing based on two-level types. This implementation is not as efficient as the default implementation but it avoids duplicate sharing which can lead to exponential blowup of the threaded heap.

Documentation

module Control.Monad

Classes

class Sharing m where

Interface of monads that support explicit sharing.

Methods

share :: Shareable m a => m a -> m (m a)

Yields an action that returns the same results as the given action but whose effects are only executed once. Especially, when the resulting action is duplicated it returns the same result at every occurrence.

Instances

Monad m => Sharing (Lazy m)

Monad m => Sharing (Lazy m)

class Shareable m a where

Interface of shareable nested monadic data types. The provided function shareArgs is supposed to map the given function on every monadic argument.

We provide instances of the Shareable class for some predefined Haskell types. For flat types the function shareArgs just returns its argument which has no arguments to which the given function could be applied.

Methods

shareArgs :: Monad n => (forall b. Shareable m b => m b -> n (m b)) -> a -> n a

Instances

Monad m => Shareable m Char

Monad m => Shareable m Int

Monad m => Shareable m Bool

(Monad m, Shareable m a) => Shareable m [m a]

An instance for lists with monadic elements.

Monad m => Shareable m [Char]

Monad m => Shareable m [Int]

Monad m => Shareable m [Bool]

(Monad m, Shareable m a) => Shareable m (List m a)

This instance allows to use nested monadic lists as argument to the Control.Monad.Sharing.share combinator.

class Convertible m a b where

Interface for convertible datatypes. The provided function convArgs is supposed to map the given function on every argument of the given value and combine the results to give the converted value.

We provide instances of the Convertible class for some predefined Haskell types. For flat types the function convArgs just returns its argument which has no arguments to which the given function could be applied.

Methods

convArgs :: (forall c d. Convertible m c d => c -> m d) -> a -> m b

Instances

Monad m => Convertible m Char Char

Monad m => Convertible m Int Int

Monad m => Convertible m Bool Bool

(Monad m, Convertible m a b) => Convertible m [m a] [b]

An instance to convert lists with monadic elements into ordinary lists.

(Monad m, Convertible m a b) => Convertible m [a] [m b]

An instance to convert ordinary lists into lists with monadic elements.

Monad m => Convertible m [Char] [Char]

Monad m => Convertible m [Int] [Int]

Monad m => Convertible m [Bool] [Bool]

(Monad m, Convertible m a b) => Convertible m [a] (List m b)

This instance enables the function Control.Monad.Sharing.convert to transform ordinary Haskell lists into nested monadic lists.

(Monad m, Convertible m a b) => Convertible m (List m a) [b]

This instance enables the function Control.Monad.Sharing.convert to transform nested monadic lists into ordinary Haskell lists.

convert :: Convertible m a b => a -> m b

Converts a convertible value recursively.

Monad transformer

data Lazy m a

Monad transformer that adds explicit sharing capability to every monad.

Instances

MonadTrans Lazy

Monad m => Monad (Lazy m)

MonadPlus m => MonadPlus (Lazy m)

MonadIO m => MonadIO (Lazy m)

Monad m => Sharing (Lazy m)

evalLazy :: (Monad m, Shareable (Lazy m) a, Convertible (Lazy m) a b) => Lazy m a -> m b

Lifts all monadic effects to the top-level and unwraps the monad transformer for explicit sharing.