Trait/Type Class Bridge

[markovejnovic]

It would be kind of neat to be able to bridge traits and type classes. My needs are currently met without that, but I could imagine that trait objects can be safely passed between Rust and haskell. Unfortunately, generics, as-is, cannot be, since it's impossible to prove which possible instantiations they have.

But an example might be:

trait Foo {
  fn foo(&self);
}

struct Bar {
  pub fn bar(&self, foo: &dyn Foo);
}

and have that emit something like

class Foo a where
  foo :: a -> IO ()

data SomeFoo = forall a. Foo a => SomeFoo a
data Bar

bar :: Bar -> SomeFoo -> IO ()

I'm still a little befuddled as to whether this is the right approach or not.