-- $setup
-- >>> :set -XOverloadedStrings

mapRight :: (b -> c) -> Either a b -> Either a c
mapRight f eith = case eith of
    Right x -> Right (f x)
    Left l -> Left l

----------------------------------------------------------------
mapRight :: (b -> c) -> Either a b -> Either a c
mapRight f eith = case eith of
    Right x -> Right (f x)
    Left l -> Left l

----------------------------------------------------------------
mapRight f eith = case eith of
    Right x -> Right (f x)
    Left l -> Left l

----------------------------------------------------------------