    -- Copyright 2022 United States Government as represented by the Administrator
    -- of the National Aeronautics and Space Administration. All Rights Reserved.
    --
    -- Disclaimers
    --
    -- Licensed under the Apache License, Version 2.0 (the "License"); you may
    -- not use this file except in compliance with the License. You may obtain a
    -- copy of the License at
    --
    --      https://www.apache.org/licenses/LICENSE-2.0
    --
    -- Unless required by applicable law or agreed to in writing, software
    -- distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
    -- WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
    -- License for the specific language governing permissions and limitations
    -- under the License.
    --
    -- | Auxiliary functions for working with values of type 'Either'.
    module Data.Either.Extra
        ( makeLeft
        , mapLeft
        )
      where

    -- | Replace the left value in an @Either@.
    makeLeft :: c -> Either a b -> Either c b
    makeLeft :: forall c a b. c -> Either a b -> Either c b
    makeLeft c
    c (Left a
    _)  = c -> Either c b
    forall a b. a -> Either a b
    Left c
    c
    makeLeft c
    _ (Right b
    x) = b -> Either c b
    forall a b. b -> Either a b
    Right b
    x

    -- | Apply a transformation only to the 'Left' values of an 'Either'.
    --
    -- Left counterpart of 'fmap'.
    mapLeft :: (a -> c) -> Either a b -> Either c b
    mapLeft :: forall a c b. (a -> c) -> Either a b -> Either c b
    mapLeft a -> c
    f (Left a
    x)  = c -> Either c b
    forall a b. a -> Either a b
    Left (a -> c
    f a
    x)
    mapLeft a -> c
    _ (Right b
    x) = b -> Either c b
    forall a b. b -> Either a b
    Right b
    x