{-# LANGUAGE NoImplicitPrelude #-}
{-# LANGUAGE Safe              #-}

module Applicative
       ( orAlt
       , orEmpty
       , eitherA
       ) where

import           Control.Applicative
import           Data.Bool           (Bool)
import           Data.Either         (Either (..))
import           Data.Monoid         (Monoid (..))

orAlt :: (Alternative f, Monoid a) => f a -> f a
orAlt f = f <|> pure mempty

orEmpty :: Alternative f => Bool -> a -> f a
orEmpty b a = if b then pure a else empty

eitherA :: Alternative f => f a -> f b -> f (Either a b)
eitherA a b = (Left <$> a) <|> (Right <$> b)