1 -----------------------------------------------------------------------------
3 -- Module : Control.Monad.Fix
4 -- Copyright : (c) Andy Gill 2001,
5 -- (c) Oregon Graduate Institute of Science and Technology, 2001
6 -- License : BSD-style (see the file libraries/base/LICENSE)
8 -- Maintainer : libraries@haskell.org
9 -- Stability : experimental
10 -- Portability : portable
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.Fix (
23 mfix -- :: (a -> m a) -> m a
25 fix -- :: (a -> a) -> a
32 fix f = let x = f x in x
34 class (Monad m) => MonadFix m where
35 mfix :: (a -> m a) -> m a
37 instance MonadFix Maybe where
41 _ -> error "empty mfix argument"
44 instance MonadFix IO where