Making js_of_ocaml compiler self-contained ?

[nojb]

Currently the js_of_ocaml compiler requires the runtime.js to be installed alongside it. dune uses ocamlfind to locate runtime.js. This means that one needs to have ocamlfind to use js_of_ocaml and it means that you need to install js_of_ocaml in order to use it.

To avoid the dependency on ocamlfind on Windows I implemented a workaround for dune (ocaml/dune#1467). However, I was wondering if you had given any thought to the idea of getting rid of the runtime.js file and simply including it as a string in the compiled compiler binary. A flags could be added to produce the file on standard output in case it is needed.

This would make the binary completely self-contained. If there is interest in this proposal I could look into implementing it (together with the necessary adaptations for dune). I recently implemented something very similar for menhir (which also depends on a "runtime" file like runtime.js) and it worked nicely.

[hhugo]

This seems reasonable.

Note that there are other runtime files sometime required and not included in runtime.js: dynlink.js, toplevel.js

[hhugo]

Work in progress #978

[hhugo]

This is now done. I'll open a PR to cleanup dune rules later

[nojb]

Great, thanks! I will try to test it in a bit.

[hhugo]

ocaml/dune#3375

[bobzhang]

@hhugo this looks great.
It seems that jsoo compile xx.byte still relies on something from findlib so that I can not copy jsoo byte code to a different machine.
There are two places where I found depend on findb:

• findlib.ml resolves findlib.conf directly, we can fake findlib.conf using OCAMLFINDLIBCONF though
• jsoo calls Findlib.find_pkg_dir "stdlib", can this be called in a lazy style when it is really needed -- otherwise I guess this still brings in dependencies on findlib/stdlib/META file

[hhugo]

@bobzhang, the findlib dependency is optional ! You should be able to build without it.
Just remove the following lines in the dune file

    (select findlib_support.ml from
     ;; Only link js_of_ocaml-compiler.findlib-support if it exists
     (js_of_ocaml-compiler.findlib-support -> findlib_support.empty.ml)
     (                                     -> findlib_support.empty.ml))

[bobzhang]

@hhugo that's exactly what I need. FYI, we have successful stories using the bytecode compiler rescript-lang/rescript#4372 -- the motivation is less dependencies for the CI