case-eval

;; clojure's (case ...) macro doesn't allow *constant-vars* in the test cases, which I find really, really annoying.
;; So, I wrote a (case-eval ...) macro that wraps (case ...) and evals the test cases.  If you like the (case ...) macro 
;; and want to use *globals*, here's your fix.  It works pretty much transparently. 

(defn count-from [start]
  (iterate inc start))

; like python
(defn zip [& lists]
  (apply map vector lists))

; like python
(defn enumerate [vals]
  (zip (count-from 0) vals))

(defn map-when-index [p? f vals]
  (for [[index val] (enumerate vals)]
    (if (p? index)
      (f val)
      val)))

(defn eval-all [val]
  (if (seq? val)
    (map eval val)
    (eval val)))

(defmacro case-eval [e & clauses]
  "Just like case, but it evals the test case so that you can use
  *constants* in the tests."
  `(case ~e ~@(map-when-index even? eval-all clauses)))

(def *abc* "ABC")

(case-eval "ABC"
  "ABC"
    :abc)

;; this doesn't work
;(case "ABC"
;  *abc*
;    :abc)

;but this does
(case-eval "ABC"
  *abc*
    :abc)

;and so does this
(case-eval "ABC"
  (*abc* "xyz")
    :abc)