Portability	portable
Stability	experimental
Maintainer	wren@community.haskell.org

Prelude.Extras

Description

This module provides additional primitive utilities I often want. They're so simple I'm surprised the Prelude lacks them, and they're too trivial to put anywhere else.

Synopsis

Documentation

swap :: (a, b) -> (b, a)Source

Swap the order of a tuple pair. This is provided by Data.Tuple as of base-4.3.0.0

class Monad m => MonadPlus m where

Monads that also support choice and failure.

Methods

mzero :: m a

the identity of mplus. It should also satisfy the equations

 mzero >>= f  =  mzero
 v >> mzero   =  mzero

(but the instance for System.IO.IO defined in Control.Monad.Error in the mtl package does not satisfy the second one).

mplus :: m a -> m a -> m a

an associative operation

Instances

MonadPlus []
MonadPlus Maybe

liftM :: Monad m => (a1 -> r) -> m a1 -> m r

Promote a function to a monad.