1 -----------------------------------------------------------------------------
3 -- Module : Control.Monad.Trans
4 -- Copyright : (c) Andy Gill 2001,
5 -- (c) Oregon Graduate Institute of Science and Technology, 2001
6 -- License : BSD-style (see the file libraries/core/LICENSE)
8 -- Maintainer : libraries@haskell.org
9 -- Stability : experimental
10 -- Portability : portable
12 -- The MonadTrans class.
14 -- Inspired by the paper
15 -- /Functional Programming with Overloading and
16 -- Higher-Order Polymorphism/,
17 -- Mark P Jones (<http://www.cse.ogi.edu/~mpj>)
18 -- Advanced School of Functional Programming, 1995.
19 -----------------------------------------------------------------------------
21 module Control.Monad.Trans (
30 -- ---------------------------------------------------------------------------
33 -- Monad to facilitate stackable Monads.
34 -- Provides a way of digging into an outer
35 -- monad, giving access to (lifting) the inner monad.
37 class MonadTrans t where
38 lift :: Monad m => m a -> t m a
40 class (Monad m) => MonadIO m where
43 instance MonadIO IO where