GNU Prolog (also called gprolog) is a compiler developed by Daniel Diaz with an interactive debugging environment for Prolog available for Unix, Windows, Mac OS X and Linux. It also supports some extensions to Prolog including constraint programming over a finite domain, parsing using definite clause grammars, and an operating system interface. The compiler converts the source code into byte code that can be interpreted by a Warren abstract machine (WAM) and converts that to standalone executables.