transformers-0.5.6.2: Concrete functor and monad transformers
Copyright (c) Ross Paterson 2012
License BSD-style (see the file LICENSE)
Maintainer R.Paterson@city.ac.uk
Stability experimental
Portability portable
Safe Haskell Safe
Language Haskell98

Control.Monad.Signatures

Description

Signatures for monad operations that require specialized lifting. Each signature has a uniformity property that the lifting should satisfy.

Synopsis
  • type CallCC m a b = ((a -> m b) -> m a) -> m a
  • type Catch e m a = m a -> (e -> m a) -> m a
  • type Listen w m a = m a -> m (a, w)
  • type Pass w m a = m (a, w -> w) -> m a

Documentation

type CallCC m a b = ((a -> m b) -> m a) -> m a Source #

Signature of the callCC operation, introduced in Control.Monad.Trans.Cont . Any lifting function liftCallCC should satisfy 

  • lift (f k) = f' (lift . k) => lift (cf f) = liftCallCC cf f'

type Catch e m a = m a -> (e -> m a) -> m a Source #

Signature of the catchE operation, introduced in Control.Monad.Trans.Except . Any lifting function liftCatch should satisfy 

  • lift (cf m f) = liftCatch (lift . cf) (lift f)

type Listen w m a = m a -> m (a, w) Source #

Signature of the listen operation, introduced in Control.Monad.Trans.Writer . Any lifting function liftListen should satisfy 

  • lift . liftListen = liftListen . lift

type Pass w m a = m (a, w -> w) -> m a Source #

Signature of the pass operation, introduced in Control.Monad.Trans.Writer . Any lifting function liftPass should satisfy 

  • lift . liftPass = liftPass . lift