module Voting.Protocol.Utils where

import Control.Applicative (Applicative(..))
import Data.Bool
import Data.Eq (Eq(..))
import Data.Foldable (sequenceA_)
import Data.Function (($))
import Data.Functor ((<$))
import Data.Maybe (Maybe(..), maybe)
import Data.Traversable (Traversable(..))
import qualified Data.List as List

-- | NOTE: check the lengths before applying @f@.
isoZipWith :: (a->b->c) -> [a]->[b]->Maybe [c]
isoZipWith f as bs
 | List.length as /= List.length bs = Nothing
 | otherwise = Just (List.zipWith f as bs)

-- | NOTE: check the lengths before applying @f@.
isoZipWith3 :: (a->b->c->d) -> [a]->[b]->[c]->Maybe [d]
isoZipWith3 f as bs cs
 | al /= List.length bs = Nothing
 | al /= List.length cs = Nothing
 | otherwise = Just (List.zipWith3 f as bs cs)
 where al = List.length as

isoZipWithM ::
 Applicative m =>
 m () ->
 (a -> b -> m c) ->
 [a] -> [b] -> m [c]
isoZipWithM err f as bs =
	maybe ([] <$ err) sequenceA $
		isoZipWith f as bs

isoZipWithM_ ::
 Applicative m =>
 m () ->
 (a -> b -> m c) ->
 [a] -> [b] -> m ()
isoZipWithM_ err f as bs =
	maybe err sequenceA_ $
		isoZipWith f as bs

isoZipWith3M ::
 Applicative m =>
 m () ->
 (a -> b -> c -> m d) ->
 [a] -> [b] -> [c] -> m [d]
isoZipWith3M err f as bs cs =
	maybe ([] <$ err) sequenceA $
		isoZipWith3 f as bs cs

isoZipWith3M_ ::
 Applicative m =>
 m () ->
 (a -> b -> c -> m d) ->
 [a] -> [b] -> [c] ->
 m ()
isoZipWith3M_ err f as bs cs =
	maybe err sequenceA_ $
		isoZipWith3 f as bs cs