module Either (
  maybeToLeft
, maybeToRight
, leftToMaybe
, rightToMaybe
, maybeToEither
) where

leftToMaybe :: Either l r -> Maybe l
leftToMaybe = either Just (const Nothing)

rightToMaybe :: Either l r -> Maybe r
rightToMaybe = either (const Nothing) Just

maybeToRight :: l -> Maybe r -> Either l r
maybeToRight l = maybe (Left l) Right

maybeToLeft :: r -> Maybe l -> Either l r
maybeToLeft r = maybe (Right r) Left

maybeToEither :: Monoid b => Maybe a -> Either b a
maybeToEither = maybe mempty