The ocaml-build-system will use the Makefile if it exists, otherwise it runs opam-install -i --prefix=out --libdir=out/lib/ocaml/site-lib

You need opam as an input.

Le 9 décembre 2020 13:35:57 GMT-05:00, zimoun <zimon.toutoune@gmail.com> a écrit :
>On Wed, 9 Dec 2020 at 19:05, divoplade <d@divoplade.fr> wrote:
>
>> I'm not sure that's the reason, but the ocaml build dance runs make
>> install, and there's no install target in the Makefile, and the opam
>> file does not need to have an install target because it installs
>> everything. I think.
>
>I do not know, I have not looked at the details, but for example:
>
>  tar -jtvf $(guix build ocaml-uutf -S)
>
>does not even show a Makefile and the Guix package looks like:
>
>--8<---------------cut here---------------start------------->8---
>    (build-system ocaml-build-system)
>    (arguments
>     `(#:tests? #f
>       #:build-flags (list "build")
>       #:phases
>       (modify-phases %standard-phases
>         (delete 'configure))))
>    (native-inputs
>     `(("ocamlbuild" ,ocamlbuild)
>       ("opam" ,opam)
>       ("topkg" ,ocaml-topkg)))
>--8<---------------cut here---------------end--------------->8---
>
>That's why I find it weird to have to patch the reactiveData Makefile
>to be able to install it.  I am probably wrong and Julien will correct
>me with their insight. :-)
>
>
>All the best,
>simon