[r6rs-discuss] Proposed features for small Scheme, part 1: a stake in the ground

[Thomas Lord]

Lord:
>> It certainly wouldn't be my ideal choice, because it has multiple
>> return values, a blasphemy.
>Why do you say that, please?
>It just seems a clean symmetry to have those.

and:

>> there are one or two things not in any Scheme
>> standard, and not implementable on top of any
>> Scheme standard afaik, that I keep missing, e.g., ARITY.
>What do you mean?  Do you mean a procedure that
>tells you the arity of a procedure?   If so,
>I think that is a confused notion because in general
>every procedure takes a flat environment as argument [...]

I think (but I'm not 100% sure) that both of these disagreements come from
the same root cause:  You think of a procedure as a way to get a computer
to do something, and I think of a procedure as the closest we can get in
this imperfect world to the Platonic ideal of a procedure, which is a
mathematical function.  Functions have one return value, by definition.
The case for arity (and yes, I mean what you said) is less clear-cut, but
/most/ mathematical functions have a simple arity either fixed or infinitely
flexible -- and even then it's generally modeled as a function of one
argument that can be an arbitrary-size vector.  I can't think of any functions
in the mathematical literature that take only prime numbers of arguments.