Clojure direct linking

;;; Add this in your project.clj to enable direct linking
;;
;; :jvm-opts ["-Dclojure.compiler.direct-linking=true"]

;; ..and now observe how this changes things:



; CIDER 0.11.0snapshot (package: 20160119.836) (Java 9-ea, Clojure 1.9.0-master-SNAPSHOT, nREPL 0.2.12)
user> (defn a [] (println "a"))
#'user/a
user> (defn b [] (a) (println "b"))
#'user/b
user> (b)
a
b
nil
user> (defn a [] (println "a!"))
#'user/a
user> (b)
a
b
nil



;; I.e. B will still refer to the old version of A and you need to recompile B to make sure it sees the new version of A:

user> (defn b [] (a) (println "b"))
#'user/b
user> (b)
a!
b
nil
user>