What is the Haskell equivalence of Rust's associated types?

CodePudding user response：

Haskell has associated type families. The Contains example on the linked page can be written in Haskell like this:

{-# LANGUAGE TypeFamilies #-}

class Contains a where
  type A a
  type B a
  contains :: a -> A a -> B a -> Bool

data Container = MkContainer Int Int

instance Contains Container where
  type A Container = Int
  type B Container = Int
  contains (MkContainer x y) a b = x == a && y == b