initial commit

src/Applicative.hs

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+module Applicative (
+  orAlt,
+  orEmpty,
+  eitherA,
+) where
+
+import Data.Monoid
+import Control.Applicative
+import Prelude (Bool, Either(..))
+
+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)