[ANN] bs-platform@7.0.0 is released


Hi all, bs-platform@7.0.0 is released, check two separate posts for what’s new.

A list of changes are available here
Currently you can try it via
npm i -g bs-platform@7.0.0
Once no serious issue founded, we will make it default for new users.
Happy Hacking !

Edit: there are something going wrong for Windows, we will publish a minor release for Windows soon


Would it be possible to update an existing ReasonReact app to use bs-platform@7.0.0?


Yes, it is a non breaking change unless you rely on the internal representation for FFI



Nevermind I just had to upgrade gentype, I will leave my post below incase someone else runs into the same problems

I tried upgrading but I get Fatal error: exception Cmi_format.Error(_)

Upgrade process:

  1. npx bsb -clean-world
  2. npm i -g bs-platform@7.0.0
  3. yarn add -D bs-platform@7.0.0
  4. yarn re:watch --> (bsb -make-world -clean-world -w)

My bs-config

  "name": "web-player",
  "reason": { "react-jsx": 3 },
  "bsc-flags": ["-bs-super-errors", "-bs-g"],
  "sources": [
      "dir": "src",
      "subdirs": true
  "package-specs": [
      "module": "es6",
      "in-source": true
  "warnings": {
    // fail compilation on missing cases in pattern-matching
    "number": "+8",
    "error": "+8"
  "suffix": ".bs.js",
  "namespace": true,
  "bs-dependencies": [
  "ppx-flags": [],
  "refmt": 3,
  "gentypeconfig": {
    "language": "typescript | untyped",
    "shims": {},
    "debug": {
      "all": false,
      "basic": false


bs-platform@7.0.1 is released and enabled by default!


For all existing BuckleScript users, the documentation now features a full migration guide to bs-platform@7.0.1: https://bucklescript.github.io/docs/en/upgrade-to-v7