Be more careful about suggestions in the presence of unknown operators #993
Description
I have a custom operator
infixl 4 <*! -- same as <$> and <*>
(<*!) :: Applicative f => f (a -> b) -> a -> f b
a <*! b = a <*> pure b
When used like f =<< g <$> x <*! y, hlint suggests changing it to f . g =<< (x <*! y), which is not correct. Replacing it with f =<< g <$> x <*> pure y gives no such suggestion (but is more verbose!), which implies that it's related to some operators being known and not. There might be other rules that have similar problems.