Control.Monad.Trans.Writer.Ref

An implementation of WriterT built on top of mutable references, providing a proper monad morphism.

An additional advantage of this transformer over the standard WriterT transformers in the transformers package is that it does not have space leaks. For more information, see https://mail.haskell.org/pipermail/libraries/2012-October/018599.html.

Documentation

data WriterRefT ref w m a

Since 0.1.0

Instances

MonadBase b m => MonadBase b (WriterRefT ref w m)

MonadBaseControl b m => MonadBaseControl b (WriterRefT ref w m)

((~) * (MCState (ref w)) (PrimState b), Monad m, (~) * w (RefElement (ref w)), MutableRef (ref w), PrimMonad b, MonadBase b m, Monoid w) => MonadWriter w (WriterRefT ref w m)

MonadTrans (WriterRefT ref w)

MonadTransControl (WriterRefT ref w)

Monad m => Monad (WriterRefT ref w m)

Functor m => Functor (WriterRefT ref w m)

Applicative m => Applicative (WriterRefT ref w m)

MonadIO m => MonadIO (WriterRefT ref w m)

MonadThrow m => MonadThrow (WriterRefT ref w m)

MonadMask m => MonadMask (WriterRefT ref w m)

MonadCatch m => MonadCatch (WriterRefT ref w m)

type StT (WriterRefT ref w) a = a

type StM (WriterRefT ref w m) a = StM m a

runWriterRefT :: (Monad m, w ~ RefElement (ref w), MCState (ref w) ~ PrimState b, MonadBase b m, MutableRef (ref w), PrimMonad b, Monoid w) => WriterRefT ref w m a -> m (a, w)

Since 0.1.0

runWriterIORefT :: (Monad m, RealWorld ~ PrimState b, MonadBase b m, PrimMonad b, Monoid w) => WriterRefT IORef w m a -> m (a, w)

Since 0.1.0

runWriterSTRefT :: (Monad m, ps ~ PrimState b, MonadBase b m, PrimMonad b, Monoid w) => WriterRefT (STRef ps) w m a -> m (a, w)

Since 0.1.0