| 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 whereSource
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
-
, for strictmfix(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