Error: Unresolved internal primitive: %caml_js_opt_meth_call about gen_js_api

[hhugo]

Likely a bug in js_of_ocaml. Can you open an issue with details on how to reproduce.

[Armael]

Ok. Done here: ocsigen/js_of_ocaml#573

[Armael]

As noticed by @hhugo on ocsigen/js_of_ocaml#573 , the ml code generated by gen_js_api from val foo : int -> unit is incorrect. With an explicit [@@js.global] annotation, it is correct.

val foo : int -> unit

produces

let (foo : int -> unit) =
  fun x1  -> ignore (Ojs.call (Ojs.int_to_js x1) "foo" [||])

while

val foo : int -> unit
[@@js.global]

produces

let (foo : int -> unit) =
  fun x1  -> ignore (Ojs.call Ojs.global "foo" [|(Ojs.int_to_js x1)|])

However, if I understand https://github.com/LexiFi/gen_js_api/blob/master/VALUES.md#automatic-binding correctly, the [@@js.global] should not be necessary and not providing it should work just the same, which is not the case currently.

[alainfrisch]

The relevant case from VALUS.md is:

If the value is a function with a single argument (named type) t -> unit, then the declaration is assumed to be a [@@js.call] method call, unless a [@js.scope] attribute has been defined in an englobing module. In this latter case, the value is assumed to be a [@@js.global] value.

Do you see something else that would contradict this interpretation?

[Armael]

Ah, now I understand the paragraph you are mentionning. I think I may have been confused by "a single argument (named type) t -> unit"; and interpreted it as "the type must literally be named t", while, if I understand correctly, t must be read as a meta-variable here?

Maybe this paragraph could be clarified a bit? Additionally, I don't know why, but when quickly reading through the paragraph, I seem to incorrectly interpret the last sentence as Otherwise, the value is assumed ..., with the Otherwise referring to the first If. Maybe reformulating things could make the whole paragraph a bit clearer.

[alainfrisch]

I've changed this section to use greek letters for meta-variables. If you have some ideas to improve the text, don't hesitate to create a PR!