RE: [Caml-list] ocamlfind? how to compile

[David Allsopp <dra-news@metastack.com>]

Mr. Herr wrote:
> I did not understand how the helpers for compilation are supposed to work.
> 
> For example I have a script that executes external programs, and needs the
> Unix module.
> 
> For script execution I have in the top of my script: #load "unix.cma";;

Good "trick" for findlib is to add:
	#use "topfind"
to ~/.ocamlinit (create it, if necessary) and then in future toploops you just say
	#require "unix";;
instead. Useful when you start using packages which depend on other packages...

> This must be removed for ocamlc or ocamlopt to work, right? Annoying.

Yes and no - a way around it is to create a wrapper script for debugging in the toploop which loads all the required libraries (or just have libraries you usually need loaded via .ocamlinit). I think it's fairly unusual that you have something that's actively intended for both the toploop *and* separate compilation so it's usually just a matter of making debugging easier in the toploop with a little script.

> But how do I compile it without manually inserting "unix.cma"/"unix.cmxa"
> into the command line? I thought the tools would do it.
> 
> This is what I tried:
> 
> strl@suse122-intel:~/Ocaml> ocamlfind ocamlc -o ml/unix2_exec
> ml/unix2_exec.ml
> ocamlfind: [WARNING] The DLL dllpcre_stubs.so occurs in multiple
> directories:
> /usr/lib64/ocaml/site-lib/pcre
> ocamlfind: [WARNING] The DLL dllpcre_stubs.so occurs in multiple
> directories:
> /usr/lib64/ocaml/stublibs

These warnings look like your package manager is installing redundant files, but that won't be breaking anything.

> File "ml/unix2_exec.ml", line 1:
> Error: Error while linking ml/unix2_exec.cmo:
> Reference to undefined global `Unix'

ocamlfind ocamlc -o ml/unix2_exec -package unix -linkpkg ml/unix2_exec.ml

I have a feeling you may run into interesting issues compiling outside of the working directory, though, but I might be misremembering something...

If you add -verbose to any ocamlfind command then it will show you all the commands it's executing (which allows you to work out error messages from the compilers).

ocamlc command line is documented in Chapter 8 of the manual: http://caml.inria.fr/pub/docs/manual-ocaml-4.00/manual022.html
findlib docs for compiling and linking with packages: http://projects.camlcity.org/projects/dl/findlib-1.3.3/doc/guide-html/x115.html

HTH,


David