| Portability | portable | 
|---|---|
| Stability | experimental | 
| Maintainer | libraries@haskell.org | 
| Safe Haskell | Trustworthy | 
Control.Monad.Fix
Description
Monadic fixpoints.
For a detailed discussion, see Levent Erkok's thesis, Value Recursion in Monadic Computations, Oregon Graduate Institute, 2002.
Documentation
class Monad m => MonadFix m where
Monads having fixed points with a 'knot-tying' semantics.
 Instances of MonadFix should satisfy the following laws:
- purity
- 
      mfix(return. h) =return(fixh)
- left shrinking (or tightening)
- 
      mfix(\x -> a >>= \y -> f x y) = a >>= \y ->mfix(\x -> f x y)
- sliding
- 
      mfix(liftMh . f) =liftMh (mfix(f . h))h.
- nesting
- 
      mfix(\x ->mfix(\y -> f x y)) =mfix(\x -> f x x)
This class is used in the translation of the recursive do notation
 supported by GHC and Hugs.
Methods
mfix :: (a -> m a) -> m a