module Data.Tup.Tup.Class where

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import Control.Applicative
import Data.Foldable (Foldable)
import Data.Traversable (Traversable)

import Data.List

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-- * the Tup class

class (Functor f, Applicative f, Foldable f, Traversable f) => Tup f where
  tupSize     :: f a -> Int
  tupToList   :: f a -> [a]
  tupFromList :: [a] -> f a

  tupUndef    :: f a -> a
  tupUndef     = undefined

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-- * misc 

-- | Safe version of 'tupFromList'.
maybeTupFromList :: Tup f => [a] -> Maybe (f a)
maybeTupFromList xs = result where
  result = if length xs == tupSize (undef result) 
    then Just (tupFromList xs)
    else Nothing    
  undef :: Maybe a -> a
  undef _ = undefined

-- | Transpose a Tup of Tups.
transposeTup :: (Tup f, Tup g) => f (g a) -> g (f a)
transposeTup = tupFromList . (map tupFromList) . transpose . (map tupToList) . tupToList

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-- | Concatenation
maybeTupConcat :: (Tup f, Tup g, Tup h) => f a -> g a -> Maybe (h a)
maybeTupConcat x y = 
  if tupSize x + tupSize y == tupSize z 
    then Just z
    else Nothing  
  where
    z = tupFromList (tupToList x ++ tupToList y)

unsafeTupConcat :: (Tup f, Tup g, Tup h) => f a -> g a -> h a
unsafeTupConcat x y = z
  where
    z = tupFromList (tupToList x ++ tupToList y)

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-- * zipping 

zipTupWith :: Applicative f => (a -> b -> c) -> f a -> f b -> f c
zipTupWith f t1 t2 = f <$> t1 <*> t2

zipTupWith3 :: Applicative f => (a -> b -> c -> d) -> f a -> f b -> f c -> f d
zipTupWith3 f t1 t2 t3 = f <$> t1 <*> t2 <*> t3

zipTupWith4 :: Applicative f => (a -> b -> c -> d -> e) -> f a -> f b -> f c -> f d -> f e
zipTupWith4 f t1 t2 t3 t4 = f <$> t1 <*> t2 <*> t3 <*> t4

zipTup :: Applicative f => f a -> f b -> f (a,b)
zipTup t1 t2 = (,) <$> t1 <*> t2

zipTup3 :: Applicative f => f a -> f b -> f c -> f (a,b,c)
zipTup3 t1 t2 t3 = (,,) <$> t1 <*> t2 <*> t3

zipTup4 :: Applicative f => f a -> f b -> f c -> f d -> f (a,b,c,d)
zipTup4 t1 t2 t3 t4 = (,,,) <$> t1 <*> t2 <*> t3 <*> t4

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