CurryInfo: base-3.4.0 / Prelude.Alternative

 
class Applicative f => Alternative f where
    -- | The identity of '<|>'
    empty :: f a
    -- | An associative binary operation
    (<|>) :: f a -> f a -> f a

    -- | One or more.
    some :: f a -> f [a]
    some v = some_ v
      where
        many_ x = some_ x <|> pure []
        some_ x = (:) <$> x <*> many_ x

    -- | Zero or more.
    many :: f a -> f [a]
    many v = many_ v
      where
        many_ x = some_ x <|> pure []
        some_ x = (:) <$> x <*> many_ x

 
| A monoid on applicative functors.

If defined, 'some' and 'many' should be the least solutions
of the equations:

* `some v = (:) <$> v <*> many v`

* `many v = some v <|> pure []`

 ["empty :: a b","(<|>) :: a b -> a b -> a b","some 1 :: a b -> a [b]","many 1 :: a b -> a [b]"]

 Alternative