Great! It seems to work wonderfully, when importing overlays that does not need inputs.

But how can you handle with overlays that require inputs like this?

hmm, at that point its a file expected to be an overlay. I don't know of a way to distinguish moduleArgs -> overlay from overlay. After one application, both are functions, and after two applications the overlay needs to use the params, so I need the real args.

I guess it can be deffered to overlay evaluation time like i did in bundlers. I could potentially make that work but even then, the preferred way to write that would be:

final: prev: (import prev.inputs.rust-overlay) final prev

that should already work.
I'll see if i can make the proposed y
syntax work though