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Should SRFI-115 character sets match extended grapheme clusters?



Hello all,

It occurs to me that users of languages that make heavy use of combining
marks will likely find the behavior of "character sets" to be quite
unintuitive if they operate on code points.  For example, they might
reasonably expect ("éè") to match either of two graphemes, and never to
match a bare 'e' or a bare combining mark.  They might also expect
(~ ("aeiou")) to match "é", even when represented as multiple code
points.

I realize that most languages (including Scheme) treat code points as
characters, that SRFI-14 character sets are really sets of code points,
and that most regexp libraries probably do the same thing.  However, it
also seems to me that these are most likely mistakes, with bad
consequences for the usability of regexps in many languages.

Should SRFI-115 try to get this right, or stick to tradition?
Thoughts?

      Mark