Hi Peter,

Most of your comments are on mark, I’ll only respond to the ones I have
something to say on.

>> > - I don't get the "need" for `parameter?`.  What is this supposed to
>> > mean when parameters can be procedures?
>>
>> Yes, they can. But they might as well not be. Thus the need for the
>> predicate.
>
> If you do this, I'd suggest also adding a continuation? predicate for
> the procedure-like objects that call/cc passes to its argument.

This is a good idea, as these are missing too! Well, if this SRFI is not
withdrawn.

> Also, it is somewhat onerous for implementations to require being able
> to discriminate procedures of different "subtypes", as that would
> require somehow tagging them with the subtype.

Yes, but that’s a matter of implementation, not semantics. I care about
semantics first, so, even if it’s hard to implement a predicate, the
predicate still matters.

>> > - In many macro systems, a syntax transformer is just a procedure
>> > (taking a syntax object and returning one). It is unclear how a useful
>> > `syntax-transformer?` could be defined. Moreover, in R7RS,
>> > `syntax-rules` is not a keyword introducing an expression form so
>> > syntax transformers are not first-class objects.
>>
>> syntax-transformer? can be defined as ##sys#macro? on Chicken or as
>> location-tracking code on other implementations, like I noted above.
>
> How does one obtain such a transformer in standard code, though?
> I think for this SRFI it makes more sense to look at what the standard
> allows or makes possible and leave standardization of predicates to
> other SRFIs that define such entities to be first-class.

Hmmmmm, fair. I might’ve said calling syntax-rules directly or
referencing e.g. do or other macro, but both of these are kind of
meta-language things not intended to be used directly.

Overall, I’m not leaning towards withdrawing this SRFI or radically
reducing the scope to basically environment? and parameter?, as these
are least controversial of all listed. But I’ll wait in case there are
more comments.

Thank you, I really value such a deep engagement with the SRFI!

Best of luck,
--
Artyom Bologov
https://aartaka.me