Question: Why do some primitives not overwrite formals?

[sebffischer]

For example, c() uses the default formals method.

Is this simply not implemented or is there more to it?

[dgkf]

The reason is simple. They were forgotten! formals for primitives were added after these were introduced and I forgot to go back and add them.

[dgkf]

Maybe to add a bit more context. One of my personal goals is to make the internals rather easy to contribute to. I've been iteratively cleaning up old primitives with little experiments to make it easier to do things like match arguments, populate default values, handle the call stack - among many other behaviors.

It wasn't so much that they were forgotten, just that a lot of this development starts as an experiment. Instead of re-writing everything with each experiment, I usually start with just a few targeted implementations to stress test an idea before committing to it throughout the whole codebase.

It's safe to say the experiment worked, so it's a good reminder to go back and flesh these all out. Thinking about it now, though... I think they could be made even simpler using something like the r! macro that was first made as an experiment for simplifying tests.

    fn formals(&self) -> ExprList {
        r! { (a = 1, b = 2, ...) }
    }

[sebffischer]

I think we don't want to directly use the r! macro, right? At least intuitively, calling into the interpreter from the interpreter feels a bit convoluted.

[dgkf]

Yeah, you're right, probably not exactly r! because it evaluates and returns a result, but maybe something like r_expr! that stops after parsing and just returns the Expr (or ExprList).

    fn formals(&self) -> ExprList {
        r_expr! { (a = 1, b = 2, ...) }
    }

is probably manageable. Not sure if I feel it's specialized enough to just call it formals! or whether it's nice to leave it broad, but naming can be decided (and changed) later.

[sebffischer]

I think this will be a good chance to familiarize myself with macros so I would love to give this one a try.