Truth-table macro in clojure

truth-table.clj

(defn bool-combinations [vs]
  (loop [vs vs
         a '({})]
    (if (empty? vs)
      a
      (recur
        (rest vs)
        (flatten
          (map
            #(list
               (assoc % (first vs) true)
               (assoc % (first vs) false))
            a))))))

;; problem 46
(defmacro pr-truth-table [vs pred]
  `(let [vs2# (filter #(= (name %) (.toUpperCase (name %))) (flatten '~pred))]
     (println (apply str (interpose "\t" vs2#)) "\t" '~pred)
     (for [{:syms ~vs} (bool-combinations vs2#)]
       (println (apply str (interpose "\t" ~vs)) "\t" ~pred))))

(pr-truth-table [A B] (and A (not B)))

;A	B 	 (and A (not B))
;true	true 	 false
;true	false 	 true
;false	true 	 false
;false	false 	 false

so, the result of line #22 is as expected, but the first argument to pr-truth-table is redundant. I can infer [A B], as is done on #17. So, now how to change lines #19 and #20 to refer to vs2# not ~vs?

Creating a “truth table” is not hard, you can use an useful tool (CKod, at http://ckod.sourceforge.net/_/) to make a “truth table”.

1. CKod homepage: http://ckod.sourceforge.net/
2. CKod online: http://ckod.sourceforge.net/_/
3. CKod forum: http://ckod.sourceforge.net/~/

Good luck to you!