Re: [Caml-list] camlp4 for js_of_ocaml toplevels

[Andy Ray <andy.ray@ujamjar.com>]

>> Is anyone working on making camlp4 extensions available in a
>> js_of_ocaml toplevel?
>>
>> I have seen the work the OCamlPro guys have done to get pa_js going by
>> hacking the compiler itself - serious kudos for that!
>>
>> Is there a reason why that's easier than js_of_ocaml compiling a
>> (static) version of camlp4?
>
> Leo White put together a custom compiler frontend for just this use
> case a while back:
>
> https://github.com/lpw25/ocaml-with-pp
>
> The idea is that you build this with a static set of camlp4 extensions,
> and it runs the input through camlp4 and then passes the AST directly
> through to the compiler (via compiler-libs).
>
> It should be reasonably easy to adapt this to a toplevel model
> as well -- let us know if you need a hand.


A good amount of hacking and I have some camlp4 code running via js_of_ocaml.

I basically took the compilation process of camlp4orf, added pa_js.cmo
and slightly modified the driver program so it took a static command
line of the form `-str "let a = b##c"`.  Also needed a bit of hacking
around temp file generation.

My next step is to try and figure out a way to get camlp4 to transform
"string -> string" rather than "hacked js_of_ocaml psuedo file ->
hacked console log in browser".  Can't say I ever really wanted to
know much about the insides of camlp4, but there you go....

One thing I noticed was when I (accidentally) had unix_isatty
returning false, and presumably camlp4 attempting to marshal a
compiler ast the js_of_ocaml runtime would die with a JSON error.  I
presume this is an issue with js_of_ocaml's marshalling code?

Cheers,
Andy