Very neat, and it led me (again) to pyrsistent (https://github.com/tobgu/pyrsistent), which does persistent data structures and which I've been pondering using with Hy (https://github.com/hylang/hy).
(edit: damn autocorrect!)
(edit: damn autocorrect!)
Hy aims to be bidirectional. Swapping around data structures will mess with that. Hy doesn't want to be intrusive, you should really be able to tell when you use Hy code.