[rescript] Not working with playwright

[searleser97]

Could you provide instructions on how to make it work with the definition files in the playwright repo ? -> https://github.com/microsoft/playwright/tree/main/packages/playwright-core/types

Do I need to run the command for just the main definition file ? or for every file ?

context: I have tried but I always get code that does not compile

I am using latest version of rescript btw (11.0.1)

[searleser97]

So, after splitting the modules into different files, I see that it created modules with cyclic dependencies.

For example:

• here the Request Interface has a function that returns a Response Interface https://github.com/microsoft/playwright/blob/ffffb81c3b935b7c9c8b310f51e2fa1fdd522843/packages/playwright-core/types/types.d.ts#L18766
• and here the Response Interface has a function that returns the Request Interface https://github.com/microsoft/playwright/blob/ffffb81c3b935b7c9c8b310f51e2fa1fdd522843/packages/playwright-core/types/types.d.ts#L18968

which creates something like the following in rescript:

module Request = {
  type t;
  @send external response: (t) => Promise.t<Null.t<Response.t>> = "response"
}

module Response = {
  type t;
  @send external request: (t) => Request.t = "request"
}

What would be the fix for those scenarios ?

[cannorin]

In this case, ts2ocaml should emit those modules as recursive (module rec). Which preset and other options did you use for emitting the binding file? It would be a bug on ts2ocaml if you used --preset full.

[searleser97]

I used that full option but didn't work, it does emit some recursive modules when it emits the resi file but it does not compile still

[searleser97]

Were you able to replicate the issue ?

[cannorin]

Sorry, I didn't have an enough free time recently to fully investigate it (a business/school year starts at April in my country). I'll look into it this week.

[cannorin]

From what I can see, playwright-core contains mutually recursive source files types/structs.d.ts and types/types.d.ts, which is the main reason why the generated binding does not compile.

ReScript does not support mutually recursive source files, and, unfortunately, it is very difficult for ts2ocaml to fix it automatically. As a workaround, ts2ocaml provide an option --merge, which just merges all the input files at the risk of breaking relative imports and increasing the output size.

Luckily, playwright-core is small and simple enough to apply the --merge option. Try running this:

$ ts2ocaml --preset minimal --merge node_modules/playwright-core/index.d.ts node_modules/playwright-core/types/*.d.ts

Then you would need to modify the output, as it contains several broken import statements and type names:

1. Assuming you have rescript-nodejs installed, replace the import statements of Node API with the following:

   /* import { ChildProcess } from 'child_process'; */
   module ChildProcess = NodeJs.ChildProcess
   /* import { EventEmitter } from 'events'; */
   module EventEmitter = NodeJs.EventEmitter.Make()
   /* import { Readable } from 'stream'; */
   module Readable = NodeJs.Stream.Readable
   /* import { ReadStream } from 'fs'; */
   module ReadStream = NodeJs.Fs.ReadStream

2. Replace URL.t with NodeJs.Url.t.
3. Replace Readable.t with Readable.t<'t> to match rescript-nodejs's implementation.
4. Replace SVGElement.t with something else or just remove it (ReScript's DOM library doesn't provide a binding for some reason).

I've successfully compiled it in PR #412 with the above options and modifications: https://github.com/ocsigen/ts2ocaml/actions/runs/8773991443/job/24074711135?pr=412#step:6:1102