Comment author: @bobzhang

Note that if we can lift the restriction that primitives can be nullary when annotated with attributes "js"
it can be simplified a bit as follows:
external is_js : bool = "%false" [@@js.call "%js"]

Comment author: chrismamo1

Is this really a desirable feature, though? One of the nice things about js_of_ocaml is that you don't need to adjust your programming style just because you're targeting a different backend.

Comment author: @bobzhang

I dont expect this flag to be used everywhere, but it's occasionally useful and will help boost js backend performance significantly.

There are two use cases for a js backend:

1. Running your ocaml program in a closed ecosystem under js platform (which is perfect for js_of_ocaml and it delivers reasonable performance)

2. Make js as the major backend (integrate your OCaml code closely with browser/nodejs ecosystem for lots of benefit). Currently my js backend(still work in progress) generate code significantly smaller than js_of_ocaml and even faster code, in this scenario, I would say it is worth to tweak the OCaml a bit to make the js a better target platform. In theory (and in practice), the OCaml generated javascript code should be running faster than hand written JS code.

I would say that the Javascript ecosystem alone is very attractive, for example, now I can debug my ocaml programs using webstorm IDE (the javascript debugger),.

Comment author: @alainfrisch

I'm in favor of exposing a primitive to query the execution backend, which could be bytecode/native/js_of_ocaml/Hongbo's new js backend/... Something similar to Sys.os_type.

Comment author: @alainfrisch

#473