I have three announcements to make about regex-* related packages. The regex-posix-0.94.1 package update provides better semantics for multiple matches. Below version 0.94, if any match was empty the matching would stop. Now the empty match is returned and the position is incremented and the searching continues. The regex-tdfa-0.71.1 package update provides the same new multiple match semantics. It also fixes a bug I found. I know of no outstanding bugs in regex-tdfa, and version 0.71.1 now passes all the tests used in regex-posix-unittest-1.0 announced below. We should care about the correctness of our operating system libraries. To help with this, I have a NEW package to announce: regex-posix-unittest-1.0 The accompanying wiki page is http://www.haskell.org/haskellwiki/Regex_Posix This new package provides an executable called regex-posix-unittest which you can install as --user or --global. The regex-posix-unittest executable with no arguments runs a suite of unit tests, all of which are described by text files in the package, the format is documented in the wiki page. By editing the text files in the package you can add to or delete from the unit tests being run. With two arguments the program expects the text first and the pattern second and will run just that match and print all the results. How does regex-posix-unittest help us care about the OS libraries? The regex-posix distributed in the GHC bundle uses the OS C library's "regex.h" API. The regex-posix-unittest package will quite likely show you that your OS C library "regex.h" API is full of bugs. If you are on Linux, it will show you a plethora of GLIBC bugs in Posix conformance. If you are on OS X, FreeBSD, or NetBSD, it will show you many bugs including a critical bug where it fail to find a match where one actually exists. These bugs in the OS library are inherited by your "sed" program as well as regex-posix and Haskell. If you are on Windows, or OpenBSD, or Solaris, or anything else, then please update the wiki page at http://www.haskell.org/haskellwiki/Regex_Posix or email me with your results so I can update the wiki. You may have evil and ingenious tests of Posix extended regular expressions to add to the test suite. Adding them is easy and if you send them to me I will put them in an updated version of regex-posix-unittest. Cheers, Chris