Separate types from implementation

[psibean]

I'd like to have it setup so the types are in their own file, and the implementation in another, where both are then imported and exported from the index file.

The problem with this is, I still want to output a single index.d.ts file. Or, at the very. least, if a .d.ts file is generated for the implementation and the types, they should also be exported from the root in some way.

I seem to have issues / problems with getting this to work, ideally without any additional tooling. Worst case scenario, may consider tsup.