Memoization directive

[vemv]

(speced/defn ^{::speced/memoize 100
               ::speced/spec    int?}
  foo ...)

...would be cool. 100 would mean up to 100 elements under a default caching strategy (e.g. LRU). Custom https://github.com/clojure/core.cache strategies could be passed.

A particularly interesting caching strategy would be per-request, a la https://github.com/steveklabnik/request_store