A :distinct-by option would be helpful. For coll-of, I've rarely needed :distinct but often needed :distinct-by.

sorry if this is a tired question, but is there any upcoming plans for supporting dynamic creation of specs other than eval-ing the macros? e.g. I want to stick a spec in a DB and use it to check some data later

@lilactown work already in progress https://github.com/clojure/spec-alpha2