Jest imports of fp-ts-std fail to resolve in 0.12 ("cannot find module")

[samhh]

We're now using conditional exports to support both ESM (bundlers) & CJS (Node), but that's unsupported in Jest for now.

You may see an error something like this:

Cannot find module 'fp-ts-std/Array' from 'path/to/file.ts'

Jest should add support soon, but until then the simplest workaround is with moduleNameMapper in your Jest config:

module.exports = {
  ...etc,
  moduleNameMapper: {
    ...etc,
    'fp-ts-std/(.*)': 'fp-ts-std/dist/cjs/$1',
  },
}

[samhh]

Note that Jest 28+ supports conditional exports, meaning fp-ts-std is supported natively without any config fiddling.