On Fri, Sep 20, 2019 at 5:42 AM Lassi Kortela <xxxxxx@lassi.io> wrote:
Not guaranteeing they are fixnums [...]

Saying they are exact integers in the range 0-127 *does* guarantee they are fixnums.
> 3) The remaining uses of "fixnum" in the section on transformation
> procedures should be changed to "exact integer" or "exact non-negative
> integer" as appropriate.  All other references shold be changed to "ASCII
> codepoint".

Since R6RS has fixnum-specialized arithmetic procedures, I'd like to
make sure people can rely on using them. They blow up (exception) on

Okay, leave these uses of "fixnum" for offsets, then.
How would `ascii-codepoint?` differ from the current `ascii-char?`?

I think it's a bit dubious that the current `ascii-char?` doesn't
recognize an integer argument as an ASCII character. I was never
entirely happy with it.

I think it's fine, and I wanted to add ascii-codepoint? as a counterpart that would only accept codepoints.
I think the name
"ascii-horizontal-whitespace?" is far too long; hence it should remain
"space-or-tab?" or be abbreviated somehow.

That's why we have code completion in Emacs and other IDEs.  But if it troubles you, you could drop "whitespace" from the name.  If an abstraction is worth a predicate, it's worth having a name for it. (Ditto with "ASCII codepoint".)

John Cowan          http://vrici.lojban.org/~cowan        xxxxxx@ccil.org
        Only do what only you can do.
        --Edsger W. Dijkstra's advice to a student in search of a thesis