{- This file is part of Vervis.
 -
 - Written in 2016, 2019 by fr33domlover <fr33domlover@riseup.net>.
 -
 - ♡ Copying is an act of love. Please copy, reuse and share.
 -
 - The author(s) have dedicated all copyright and related and neighboring
 - rights to this software to the public domain worldwide. This software is
 - distributed without any warranty.
 -
 - You should have received a copy of the CC0 Public Domain Dedication along
 - with this software. If not, see
 - <http://creativecommons.org/publicdomain/zero/1.0/>.
 -}

module Data.Either.Local
    ( maybeRight
    , maybeLeft
    , requireEither
    )
where

import Prelude

maybeRight :: Either a b -> Maybe b
maybeRight (Left _)  = Nothing
maybeRight (Right b) = Just b

maybeLeft :: Either a b -> Maybe a
maybeLeft (Left a)  = Just a
maybeLeft (Right _) = Nothing

requireEither :: Maybe a -> Maybe b -> Either Bool (Either a b)
requireEither Nothing  Nothing   = Left False
requireEither (Just _) (Just _)  = Left True
requireEither (Just x) Nothing   = Right $ Left x
requireEither Nothing  (Just y)  = Right $ Right y