Hi, I'm trying to implement FixStyle[1] program of PLEAC[2] for Haskell. (It's missing in the Haskell version of PLEAC.) For this purpose, I needed regular expressions. (Now, I have two problems!) Despite, my code is, IMHO, quite purely functional, Regex.PCRE.String functions totally mess up the design with impure functions they introduce even for really simple string matching stuff. If you'd check out the sources[3], you'll see below impure functions. transDictRegex :: IO PCRE.Regex matchRegex :: String -> IO (String, String, String) translate :: String -> IO String However, if I'm not mistaken, above functions _should_ be absolutely pure. Is it possible to encapsulate impure PCRE functions into their pure equivalents? BTW, why are PCRE functions impure? Regards. [1] http://pleac.sourceforge.net/pleac_perl/strings.html [2] http://pleac.sourceforge.net/ [3] http://hpaste.org/fastcgi/hpaste.fcgi/view?id=14422