[Haskell-cafe] Generate Fortran 77 parser from a yacc grammar using Happy

I have stumbled upon the following F77 yacc grammar: http://yaxx.cvs.sourceforge.net/viewvc/yaxx/yaxx/fortran/fortran.y?revision=... . How can I make a Fortran 77 parser out of this file using Happy<http://www.haskell.org/happy/> ? Why is there some C?/C++? code in that .y file?