Reasonml to Rescript migration

Hey there! I’ve been following the last updates on the rescript syntax! I’d like to know what would be the migration path for the following:

We have a big monorepo codebase written in reasonml! I’ve tried updating bs-platform to rescript but the problem we have is that in vscode, we loose intellisense and compilation errors highlighting for old reasonml syntax because new rescript cli and bs-platform seem not to be compatible.

We cannot migrate yet all this code because we use some custom infix operators across all the codebase like “decco”, “bs-let” and operators like “>>=”.

  • Is there a way to have this error highlighting back? or what would be the recommended migration path?
  • What would be the replacement, for things like “decco” and “bs-let”

Thanks on advance for all the work you’re doing guys, amazing stuff, we are really happy with the tooling and the language!


This is blocking me as well, and from what I understand ReasonML syntax is deprecated (for Rescript) but Ocaml is not? Possibly to keep infixes I was planning to convert it all to Ocaml syntax.

Hi, decco should continue to work in ReScript.

The recommendation for bs-let is to use and promise chaining instead, e.g. promise1->then(x => ...)->then(y => ...).

Overall, I think the recommended migration path is to migrate everything in one shot. In your case it looks like you’ll need to do some prep work as discussed above.

1 Like