Clojure destructure map using :keys with qualified keywords not working

Question

I've tried this with both 1.7.0 and 1.8.0 and it appears that Clojure does not destructure maps using :keys whose keys are fully qualified. I don't think it has to do with being in the tail on the arguments as it doesn't work when I switch around the function argument positions as well.

(ns foo.sandbox)

(def foo ::foo)
(def bar ::bar)

(defn normalize-vals
  [mmap & [{:keys [foo bar] :as ops}]]
  (println "normalize-vals " ops " and foo " foo " bar" bar))

(normalize-vals {} {foo 1 bar 2})

=> normalize-vals  {:foo.sandbox/foo 1, :foo.sandbox/bar 2}  and foo  nil  bar  nil

However; this works:

    (defn normalize-vals
      [mmap & [{a foo b bar :as ops}]]
      (println "normalize-vals " ops " and foo " a " bar" b))

    (normalize-vals {} {foo 1 bar 2})

=> normalize-vals  {:cmt.sandbox/foo 1, :cmt.sandbox/bar 2}  and foo  1  bar  2

Is this a defect?

Answer 1

You are destructuring using unqualified keywords, so instead of:

[mmap & [{:keys [foo bar] :as ops}]]

you should use

[mmap & [{:keys [::foo ::bar] :as ops}]]

You can use clojure.walk/macroexpand-all to expand normalize-vals:

(clojure.walk/macroexpand-all '(defn normalize-vals
                                 [mmap & [{:keys [foo bar] :as ops}]]
                                 (println "normalize-vals " ops " and foo " foo " bar" bar)))

=> (def normalize-vals (fn* ([mmap & p__26720] (let* [vec__26721 p__26720 map__26722 (clojure.core/nth vec__26721 0 nil) map__26722 (if (clojure.core/seq? map__26722) (. clojure.lang.PersistentHashMap create (clojure.core/seq map__26722)) map__26722) ops map__26722 foo (clojure.core/get map__26722 :foo) bar (clojure.core/get map__26722 :bar)] (println "normalize-vals " ops " and foo " foo " bar" bar)))))

The important part of the expansion to note is:

foo (clojure.core/get map__26722 :foo) 
bar (clojure.core/get map__26722 :bar)

The keys in the map destructuring are therefore converted to keywords at compile time and the values from the foo and bar vars in the namespace will not be used.