I recall rewriting a several thousand line program that was written in a preprocessing language that compiled to fortran that was homerolled by some random guy

I recall rewriting a several thousand line program that was written in a preprocessing language that compiled to fortran that was homerolled by some random guy that was just so ahead of the game at the time that he basically wrote an extension of fortran with all the macros he made and rolled into one thing. The rewrite was 100 lines long.