Haskell multifilter

Question

I want to filter a list by predicates curried from another list. For instance:

multifilter :: (a -> a -> Bool) -> [a] -> [a] -> [a]
multifilter _ _ [] = []
multifilter _ [] _ = []
multifilter f (x:xs) ys = (filter (f x) ys) ++ (multifilter f xs ys)

With usage such as:

prelude> multifilter (==) [1,2,3] [5,3,2]
[2,3]

Is there a standard way to do this?

Answer 1

You can use intersectBy:

λ> :t intersectBy
intersectBy :: (a -> a -> Bool) -> [a] -> [a] -> [a]
λ> intersectBy (==) [1,2,3] [5,3,2]
[2,3]

You can use hoogle to search functions using type signature and finding them.