This is a version of sed based on POSIX "The Open Group Base Specifications Issue 7" 
IEEE Std 1003.1-2008.  
This version of the Haskell Sed uses regex-posix package to parse all regular 
expressions. At the moment it doesn't supports the back-references in the RE.

Usage: Hsed [-n] script [file...],
       Hsed [-n] -e script [-e script]... [-f script_file]... [file...],
       Hsed [-n] [-e script]... -f script_file [-f script_file]... [file...]

To run tests suite build and run TestSuite.hs:
$ ghc --make TestSuite.hs
$ ./TestSuite --dir ../tests --inp in --ok ok