It does not matter what arity are types, I meant one could parametrize call to use Scaffold with types, not parametrized types themselves.

Parameteized types would be handled for granted. I have removed “parametrized” from the tagline to avoid misunderstanding, thanks.

But what about adding them outside of the quote, rather than adding them to the quote you are writing anyway? Or maybe you might write them in their own dedicated quote before the final quoted AST that is returned?

The main reason to use the explicit AST-notation is to pattern-match on it (which you cannot do with quoted fragments because the meta fields of {name, meta, arguments} would often not match). In places where you are constructing AST it is virtually always more understandable to work with quote/unquote, in my humble opinion .

For the sake of consistency I posted it here: Elixir Blog Posts - #627 by mudasobwa