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
bignums.
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".)