Awesome, you don't happen to have published the patch to github or Assembla have you? I have a suspicion that Rich will not replace the existing memoize with a SoftReference version as it is quite specific of the underlying architecture to provide this functionality. Rich is currently focused very much on CINC (Clojure in Clojure) and probably wants to avoid exposing implementation details to increase portability to other platforms (such as .NET). All the same, it would be great to have a SoftReference memoize in the contrib library for example.