-- |
-- This module provides the following instances:
--
-- * @instance 'Monad' m     => 'Applicative' ('StateT' s m)@
--
-- * @instance 'MonadPlus' m => 'Alternative' ('StateT' s m)@
module StateInstances where

import Control.Applicative
import Control.Monad.State

instance Monad m => Applicative (StateT s m) where
  pure  = return
  (<*>) = ap

instance MonadPlus m => Alternative (StateT s m) where
  empty = mzero
  (<|>) = mplus