{-# OPTIONS_GHC -Wall #-}

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{- |
Module      :  Control.MonadOr
Description :  MonadOr definition.
Copyright   :  (c) Paulo Silva
License     :  LGPL

Maintainer  :  paufil@di.uminho.pt
Stability   :  experimental
Portability :  portable

Monad definition satisfying the Monoid and Left Catch laws as refered in
<http://www.haskell.org/haskellwiki/MonadPlus_reform_proposal>

-}

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module Control.MonadOr (
  MonadOr,
  morelse
 ) where

import Control.Monad

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class MonadPlus m => MonadOr m where
  morelse :: m a -> m a -> m a

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instance MonadOr [] where
  morelse [] b = b
  morelse a _ = a

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-- This instance is equal to mplus for maybe
instance MonadOr Maybe where
  morelse = mplus

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