Re: [Caml-list] Utop Difficulties with C callbacks

[Jeremie Dimino <jdimino@janestreet.com>]

I have to run, but think the problem is that piqilib is not building a
shared library for its C stubs: if you want to be able to load a
library with C stubs in the toplevel, the stubs must be packed into a
shared library. You normally do this with ocamlmklib and pass a -dllib
option when building the .cma. oasis does all that automatically.

This other option is to build the bytecode executable with -custom,
which will link the C libraries, the ocamlrun executable and the
bytecode into a single native executable.

So simply adding -custom when building a custom utop should work. But
the proper fix is to update piqilib to build a .so for its C stubs.



On Thu, Mar 19, 2015 at 6:19 PM, Kenneth Adam Miller
<kennethadammiller@gmail.com> wrote:
> So, I've been working for a while with a library and I've made a good
> iteration. My code compiles and is nice, it does what is expected, but it
> depends on a library, Piqi, that doesn't want to play nice in the
> interpreter. I want to be a good citizen and do my homework and due
> diligence, but nothing I do seems to make utop want to play nice with piqi.
>
> Here goes:
>
> When I execute utop -require mypackage repository with the newly built
> package mypackage, but I get this error:
>
> File "_none_", line 1:
> Error: The external function `camlidl_piqi_c_piqi_strtoull' is not available
>
> I checked out piqi locally, and pinned the package to my local build, where
> I tried to ensure that the appropriate .c file is getting compiled and
> linked into the cma and cmxa. They are without a shadow of a doubt. I then
> thought maybe I would add an include directive to utop to tell it to pick up
> the mli where the the external func : type = "name" is. Nope.
>
> I've done everything I can, from adding all combinations of additional
> piqirun/piqilib/piqirun.pb/piqirun.ext combinations to the _oasis file that
> specifies the serialization to trying to build my own utop to adding
> additional require statements and include statements in the utop script. So
> after trying to add the dependency to BuildDepends for myouterlib, I had
> backed off to just adding the mylibrary to the specific binary that consumes
> it, which is where my changes are (in that binary).
>
> I even went so far as to just try and get the changes compiled into a custom
> utop. Nope. I got errors and errors; I built it with:
> ocamlbuild -use-ocamlfind -pkg threads -pkg utop -pkg myouterlib -pkg camlp4
> -pkg core_kernel customtop.top
>
> (At the time I ran this, I had bap package's _oasis updated with the
> appropriate compile BuildDepends so that it would link mylibrary too)
>
> and I had the let () = Utop_main.main ();; in "utopmain.ml" and customary
> customtop.mltop containing just "Utopmain". I got:
>
> (Unbound value <everything I need *and* that's contained in mylibrary which
> is specified in -pkg!>)
>
> I don't know what else to do besides ship code that is watered down without
> an interactive component. :/



-- 
Jeremie