Dear all This is my first post, so I'm sorry of this is a bit unusual or not what this mailing list is for. I've googled and search mailing list archive, but didn't find anything. I'm using OCaml (version 3.08.4) on my PowerBook, Mac OS 10.4.3, to develop my Dissertation, and have run into a big problem, which I can't find a solution to... The project is a tool for language writers. You give it a language defn in a made up meta language (test.ott), and it spits out yacc, lex, ocaml datatypes (based on sugar and the ocfg tool by Stephen Tse) and some code to calculate the binding of variables within expressions (similar to alphaCaml, but not). The project is in its early stages, lots more work to do, but here is the problem at the mo: When I add some code (which typechecks and compiles correctly) the tool generates empty files. If I then comment out this code, the files are back again. The code is in generate_alpha.ml, lines 207-212, and this files has nothing to do with the generated Yacc or Lex. Very strange. I've tried compiling it to byte code and native, to no avail. The project is very modular, those files beginning with yacc_* generate yacc, lex_* generate lex and so on... I even made it spit the code generated out to the terminal, and its there! It just doesn't write to the file! Is there a problem on OS X with writing files? If any one has any ideas, please reply! this is a show stopper for me. I've attached my project, to build it with a quick test to highlight the problem, untar and do a: make test And it compiles and works fine. Uncomment the lines in generate_alpha.ml, type make test and most of the files the tool generates are empty!! (look in test/) If you put VERSION=NATIVE on the make cmd line then it will compile with ocamlopt. Same results on my computer. Any help would be much appreciated! Cheers Tom