A word of comment: Markus uses a slightly more advanced feature of ocamlbuild, which is the ability to set compilation tags not in the ocamlbuild invocation command, as you've been using, but in a dedicated "_tags" file in the repository:
  https://bitbucket.org/mmottl/ocaml-playground/src/65d3ec500ac36683e18d0b84dbf98115f82ea8af/lacaml_test/_tags

You can see the line "true: package(lacaml)", which means that all compilation commands needed to compile whatever target is required (test.native, test.docdir/index.html...) will use the lacaml ocamlfind package (this only works if ocamlbuild is invoked with -use-ocamlfind, which is the case in his Makefile).

On Thu, Feb 21, 2013 at 3:34 PM, Markus Mottl <markus.mottl@gmail.com> wrote:
Hi,

I've just set up a small, self-contained example "lacaml_test" in my
OCaml playground repository on Bitbucket:

  https://bitbucket.org/mmottl/ocaml-playground

Just clone the repository to your computer:

  hg clone ssh://hg@bitbucket.org/mmottl/ocaml-playground

Then follow the instructions in the README files.

Regards,
Markus

On Thu, Feb 21, 2013 at 8:25 AM, Elisa Rebolini <erebolini@gmail.com> wrote:
> I've installed lacaml 7.0.3 by following the installation procedure
>         'ocaml setup.ml -configure'
>         'ocaml setup.ml -build'
>         'ocaml setup.ml -install'
> The path to the lacaml package is /usr/local/lib/ocaml/site-lib/lacaml
> and my Makefile is
>
> hostname := $(shell uname -n)
>
> # Default
> LIB=-I,+site-lib/lacaml
>
> ifeq ($(hostname),clastos)
> LIB=-I,+site-lib/lacaml
> endif
>
> ifeq ($(hostname),bulle)
> LIB=-I,/usr/local/lib/ocaml/3.12.1/lacaml
> endif
>
> all:
>         ocamlbuild -libs bigarray,lacaml,str,unix -verbose 2 -cflags $(LIB)
> -lflags $(LIB) molexc.native
>
> clean:
>         ocamlbuild -clean
>
> doc:
>         ocamlbuild -libs bigarray,lacaml,str,unix -verbose 2 -cflags $(LIB)
> -lflags $(LIB) molexc.docdir/index.html
>
> thanks
> --
> Elisa
>
> Le 21/02/2013 14:11, Gabriel Scherer a écrit :
>> It would help to have more precise information about your setup. Could you
>> detail how you installed lacaml on your system, and provide a directory
>> tarball for a simple project allowing to reproduce your problem (with the
>> _tags file etc.)?
>>
>> On Thu, Feb 21, 2013 at 2:07 PM, Elisa Rebolini <erebolini@gmail.com> wrote:
>>
>> Hello list,
>> I'm developping a quantum chemistry software with ocaml and use lacaml
>> as a binding to the LAPACK and BLAS libraries.
>> I have a warning at the compilation with ocamlbuild
>>         Warning: Failed to build the module Lacaml requested by ocamldep
>>         mid rule ocaml: ml -> cmo & cmi (%=parser_epsilon ): cache hit
>> but the compilation is still successful and the program works as
>> expected but when I try to compile the documentation I have an error
>>         Error: Unbound module Lacaml
>> I'm not very skilled (yet?) with caml so any help would be very much
>> appreciated.
>> Thanks a lot
>>>
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>>
>
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--
Markus Mottl        http://www.ocaml.info        markus.mottl@gmail.com