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1 point by eds 5766 days ago | link | parent

> Still, I wonder - how does CLOS implement this? How about for variadic functions?

I don't think CLOS lets you check types on &rest, &optional, or &key parameters. So you couldn't use CLOS for the current behavior of '+.

Also note that CLOS only works on methods with "congruent lambda lists", that is, methods with the same number of required, optional, and keyword arguments. So you can't have

  (defmethod foo ((a type-a)) ...)
  (defmethod foo ((b type-b) &optional (c ...)) ...)

1 point by almkglor 5765 days ago | link

ah, I see. So I suppose this greatly simplifies things then.

Hmm. This certainly seems easier to hack into arc. We could have each method start with a generic function whose lambda list we have to match.

As an aside, currently the base of Arc lambda lists are simply &rest parameters (i.e. optional parameters are converted into rest parameters with destructuring). Should we match on the plain rest parameters or should we properly support optionals?