Most of the time we debug our code using the Errormsg module along with the pretty printer. But if you want to use the Ocaml debugger here is an easy way to do it. Say that you want to debug the invocation of cilly that arises out of the following command:
cilly -c hello.c
You must follow the installation instructions to install the Elist support files for ocaml and to extend your .emacs appropriately. Then from within Emacs you do
ALT-X my-camldebug
This will ask you for the command to use for running the Ocaml debugger (initially the default will be “ocamldebug” or the last command you introduced). You use the following command:
cilly --ocamldebug -c hello.c
This will run cilly as usual and invoke the Ocaml debugger when the cilly engine starts. The advantage of this way of invoking the debugger is that the directory search paths are set automatically and the right set or arguments is passed to the debugger.