Differentiate between fn (.) and fn(.())

[bobzhang]

Relevant: rescript-lang/rescript#3429

Currently they are all de-sugared into OCaml syntax fn () [@bs]

The thing is that in BuckleScript, since there is no syntax space for arity zero, so we make a special form that fn () [@bs] is treated arity zero application.

I wonder Reason could make a difference here which feels more intuitive:

fn (.) --> arity zero -> fn () [@bs]
fn (. ()) --> arity 1 -> let unit = () in fn unit of course, some care need to be taken to avoid name collision

[anmonteiro]

This would need to remain compatible with OCaml, and I don’t see a viable way to do that