Control.Monad.Supply

Support for computations which consume values from a (possibly infinite) supply. See http://www.haskell.org/haskellwiki/New_monads/MonadSupply for details.

Documentation

class Monad m => MonadSupply s m | m -> s where

Methods

supply :: m s

peek :: m s

exhausted :: m Bool

Instances

MonadSupply s (Supply s)

(Monoid w, MonadSupply s m) => MonadSupply s (WriterT w m)

MonadSupply s m => MonadSupply s (ReaderT r m)

MonadSupply s m => MonadSupply s (StateT st m)

MonadSupply s m => MonadSupply s (ExceptT e m)

Monad m => MonadSupply s (SupplyT s m)

data SupplyT s m a

Supply monad transformer.

Instances

Monad m => MonadSupply s (SupplyT s m)

MonadTrans (SupplyT s)

Monad m => Monad (SupplyT s m)

Functor m => Functor (SupplyT s m)

MonadFix m => MonadFix (SupplyT s m)

(Monad m, Functor m) => Applicative (SupplyT s m)

MonadIO m => MonadIO (SupplyT s m)

data Supply s a

Supply monad.

Instances

MonadSupply s (Supply s)

Monad (Supply s)

Functor (Supply s)

MonadFix (Supply s)

Applicative (Supply s)

Monoid a => Monoid (Supply s a)

Monoid instance for the supply monad. Actually any monad/monoid pair gives rise to this monoid instance, but we can't write its type like that because it would conflict with existing instances provided by Data.Monoid. instance (Monoid a, Monad m) => Monoid (m a) where

evalSupplyT :: Monad m => SupplyT s m a -> [s] -> m a

evalSupply :: Supply s a -> [s] -> a

runSupplyT :: Monad m => SupplyT s m a -> [s] -> m (a, [s])

runSupply :: Supply s a -> [s] -> (a, [s])

supplies :: MonadSupply s m => Int -> m [s]

Get n supplies.