(b -> a) -> (c -> a) -> coproduct b c -> a

either :: (a -> c) -> (b -> c) -> Either a b -> c
base Prelude, base Data.Either
Case analysis for the Either type. If the value is Left a, apply the first function to a; if it is Right b, apply the second function to b.
orP :: (a -> Bool) -> (b -> Bool) -> (a, b) -> Bool
fgl Data.Graph.Inductive.Query.Monad