module Clean.Unit where

import qualified Prelude as P
import Clean.Core
import Clean.Monoid
import Data.Tree

class Unit f where
  pure :: a -> f a
instance Unit (Either a) where pure = Right
instance Monoid w => Unit ((,) w) where pure a = (zero,a)
instance Unit ((->) b) where pure = const
instance Unit [] where pure a = [a]
instance Unit Tree where pure a = Node a []
instance Unit IO where pure = P.return