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I don't think this PR actually fixes #15269, this PR adds support for import { generate } from "@babel/generator" given ESM-to-CJS transforms applied. The pure ESM import, either the default one or the named one in this PR, would still be blocked until Babel 8.

@JLHwung But it actually works, and really fix mentioned issue. I mean, that at least we can import and use @babel/generator from .mjs files.
Quick experiment:

$ node --version
v22.13.1
$ npm install @babel/generator

Create test.mjs

import {generate} from "@babel/generator";
import parser from "@babel/parser";

const code = `function square(n) {
  return n * n;
}`;

const ast = parser.parse(code);

const output = generate(ast, {}, code);
console.log(output);

Next, I patched file `node_modules/@babel/generator/lib/index.js

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = generate;

exports.generate = generate;  // <--- Inserted this line
var _sourceMap = require("./source-map.js");
var _printer = require("./printer.js");

And after

$ node test.mjs
{
  code: 'function square(n) {\n  return n * n;\n}',
  decodedMap: undefined,
  __mergedMap: [Getter],
  map: [Getter/Setter],
  rawMappings: [Getter/Setter]
}

Thank you for your experiment. The issue #15269 is that

import generate from "@babel/generator"
generate(bla)

does not work. It will never work because generate is a namespace as Babel 7 is CJS. One would have to access from the default binding:

import generate from "@babel/generator"
generate.default(bla)

When you use Babel 8 (ESM), the first usage will work, but Babel 8 is still in alpha.

In this PR, we added a new generate export so that the named import works

import { generate } from "@babel/generator"
generate(bla)

and it should work for both Babel 7 CJS and Babel 8 ESM. But this PR does not make the first usage work, this is why I stated that this PR does not fix #15269 but rather offered a more convenient API access so that users don't have to deal with CJS/ESM import interop.

Agreed! Thanks for the detailed explanation. Technically, it's not a fix, it's a workaround. 🤝

@nicolo-ribaudo Of course, I will be happy to update the documentation! Can I do PR in babel/website in advance with this PR or better wait until this PR is merged?

This will take a while (1 month?) to be merged because we are going to wait for the next minor release.

Please go ahead, I'll take care of merging everything at the right time :)

The @types/babel__generator package is still outdated. How do you guys use it in a typescript project?

@seancheung Please report it to https://github.com/DefinitelyTyped/DefinitelyTyped, @types/babel__generator is not maintained by us.

@seancheung I created PR to DefinitelyTyped (wow, it's a huge git repo — 24Gb on disk)

If this package is in TypeScript now, can you all just publish types with your package? Seems like extra work and pain to have to update this in two places.

In the next major. We were considering doing it now already, but the new type definitions cause significant breakage compared to the DT ones.

Interesting, I guess I didn't think they'd be all that different. No worries, of course, just asking!

@seancheung I created PR to DefinitelyTyped (wow, it's a huge git repo — 24Gb on disk)

Thanks bro!
BTW you could just do a shallow clone and it should be much smaller 👍