Imlementing regular expression

John,

in a previous post, you mentioned that your proposal makes 
implementation of regular expressions easier because they
can just use existing Posix engines.

I am not sure it is important, or even usable,
because Posix regexps are not Unicode-aware,
and because implementing full XML Schema regular expressions
took just one evening (and under one thousand lines in C).

Re-writing the w3c schema regexp library in Scheme from scratch
took another evening.

C implementation is much (the more to match, the better) faster
than Posix regexp implementations available for me. 

Scheme implementation is slower than C (with SCM), but still
almost as fast as calling Posix C regexp library from Scheme
code.

That is, implementing W3C Schema regular expressions is an easy
and simple job, which due to a number of causes, results in
a faster, more compact and better maintainable code, suited
for processing of Unicode.

David Tolpin