Haskell - What is Control.Applicative.Alternative good for?
Sometimes the <|>
operator is quite useful:
foldl1 (<|>) [Nothing, Just 5, Just 3]
-- Just 5
It's commonly used with parser combinators. For example, if space
is a parser combinator that matches a single whitespace character, many space
would be one that would match consecutive whitespace.
I can agree that it's slightly out of place in Control.Applicative
, though.