[v5] Export internal types

[apancutt]

With v5 now being ESM and using the exports field in package.json, we're no longer able to pluck out internal types for use in our own libraries.

Just one example (of many), if we wanted to implement a camelCase(value: string, options?: CamelCaseOptions) function we now need to copy/paste the CamelCaseOptions type from type-fest since it is no longer exposed.

Regarding #676 - I realize these types are lacking docs/tests so should not be included in the top-level export, but developers should be able to opt-in to using them (like we could pre-v5).

Suggestion: add the following to the exports field:

"./source/internal": {
  "types": "./source/internal/index.d.ts"
},
"./source/*": {
  "types": "./source/*/index.d.ts"
}

[sindresorhus]

This is very much intentional and one of the good things about moving to exports in package. It allows us to hide internal types. They are internal for a reason. It lets us iterate on them, rename, change behavior etc, without having to think whether it breaks consumers.

As #676 says, we are happy to expose internal types, but it should be done properly.

You could also copy-paste the internal types you need.

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Just one example (of many), if we wanted to implement a camelCase(value: string, options?: CamelCaseOptions) function we now need to copy/paste the CamelCaseOptions type from type-fest since it is no longer exposed.

This specific issue is fixed: https://github.com/sindresorhus/type-fest/releases/tag/v5.0.1