I've been thinking how it'd be nice to have available in Guile a number of purely functional datatypes, these being hashmaps, vectors, and sets.
Those are core data types of Clojure. It'd be nice if the canonical Scheme versions of these types have Clojure-compatible semantics. This will make it easy to turn Scheme implementations into partial implementations of Clojure. This is already being attempted in Lokke (https://github.com/lokke-org/lokke).
