On: Translating Haskell to C++ metaprogramming

[Nullabillity]

Not quite. It's equivalent to either

    contains :: (NameClass, QName) -> Bool

or

    contains :: NameClass -> (QName -> Bool)

In other words, you can treat it as a function taking two arguments, or one function taking one argument and returning another function.

[theseoafs → Nullabillity]

It is equivalent to the second, not the first. The first is a completely distinct type -- though you can certainly write a function with that type, given the original function, by uncurrying it.

[saurik → theseoafs]

FWIW, I think the person you are responding to is using the non-Haskell requested mental syntax used by the person who asked the original question, in order so they better understand the semantics (even if at a cost of confusing them for later development in Haskell).

[Nullabillity → saurik]

Yup. They're distinct types, but mentally they are the same (and the standard library has functions to convert between the two forms).