module Clean.Traversable(
  module Clean.Foldable,module Clean.Applicative,

  Traversable(..),

  traverse,foreach,transpose
  ) where

import Clean.Classes
import Clean.Core
import Clean.Foldable
import Clean.Applicative
import Data.Tree

class Foldable t => Traversable t where
  sequence :: Applicative f => t (f a) -> f (t a)
instance Traversable (Either a) where
  sequence = pure . Left <|> map Right 
instance Traversable [] where
  sequence (x:xs) = (:)<$>x<*>sequence xs
  sequence [] = pure []
deriving instance Traversable ZipList
instance Traversable Tree where
  sequence (Node a subs) = Node<$>a<*>sequence (map sequence subs)
deriving instance Traversable ZipTree

traverse f t = sequence (map f t)
foreach = flip traverse
transpose = sequence