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> > From: Brad Lucier <lucier@xxxxxxxxxxxxxxx> > > > I hope you don't try to define predicate->bitset in a later SRFI ;-). > > > > Well, I guess it's too late to put it into the lset-... suite of > > operations in SRFI 1... > > My unstated (definitely understated) point is that predicate->bitset > will never return in the general case, which isn't much different from > how long it will take predicate->char-set to return on systems that use > a four-byte character representation. > > Yep, I understood. Just a little bit of wry academic humor there, on my > part. > > Clearly people who use 4-byte char types will have to stear clear of > ops that are linear in the type size. > -Olin > I'm trying to think of a way to embed an escape procedure into predicate->char-set[!]. Is the following legal? Does it solve the "I only want to examine ASCII characters to build this set" problem? (define cs (let ((result (char-set))) (call-with-current-continuation (lambda (exit) (predicate->char-set! (lambda (ch) (or (char=? ch #\newline) (and (> (char->integer ch) 127) (exit)))) result))) result)) I suppose one would need a guarantee that characters are examined in (char->integer ch) order, and it would have to add the character to result immediately when the predicate returned true, and it isn't linear update, and ... Oh well. Brad