As far as the lack of a regex library in Arc you could probably make use of PLT MzScheme's built-in support for regular expressions (http://download.plt-scheme.org/doc/mzscheme/mzscheme-Z-H-10....) or the pregexp.ss library (http://download.plt-scheme.org/doc/mzlib/mzlib.html) for Perl-style regex. Anarki allows you to call scheme functions from within arc by using $:
($ (sin 1))