annoymous function was not handled correctly

[bobzhang]

type foo =
| Bar
| Baz;
let x = 2;
let fooToString =
fun
| Bar => string_of_int (x) + "Bar"
| Baz => "Baz";

npx bsc -format xx.re

type foo =
  | Bar
  | Baz
let x = 2

let fooToString = x =>
  switch x {
  | Bar => string_of_int(x) + "Bar"
  | Baz => "Baz"
  }

[bobzhang]

ping? This seems a serious bug

[IwanKaramazow]

@bobzhang will prioritize, looking into this today

[bobzhang]

IIUC, this is a bug only in printing, in rescript syntax, all parameters should be named, is it correct?

[IwanKaramazow]

Yes, to explain it in ast-terms, we don't have syntax for Pexp_function only for Pexp_fun. When you convert/print fun | (Pexp_function) from OCaml or Reason we transform it into a Pexp_fun with switch x { | … }.

I've looked into the naming problem, but the only "correct" way would be to re-introduce a syntax for Pexp_function. The idea was that forcing naming of parameters would be a good thing…

But this can be re-done. I'm open to suggestions.

[bobzhang]

I hit a bug when doing the formatting, the function get broken is below:

let rec add x data = function
    Empty ->
    Node(Empty, x, data, Empty, 1)
  | Node(l, v, d, r, h) ->
    let c = compare x v in
    if c = 0 then
      Node(l, x, data, r, h)
    else if c < 0 then
      bal (add x data l) v d r
    else
      bal l v d (add x data r)

So the conversion is of high risky, a temporary solution is to change names from x to argument to reduce the risk.

Edit: since the parser already know one of the argument is called x, it should error out for such transformation to tell users to adapt their code

[stale[bot]]

The rescript-lang/syntax repo is obsolete and will be archived soon. If this issue is still relevant, please reopen in the compiler repo (https://github.com/rescript-lang/rescript-compiler) or comment here to ask for it to be moved. Thank you for your contributions.