View difference between Paste ID: xpsMjBUA and QYGTHAXF

 ;; Backward Chaining
-	(doseq [rule (fetch-rules goal)]
+
-		(if (empty? rule)
+(ns backward)
-			0.9  ; a truth value
+(import '(java.util.concurrent Executors ExecutorCompletionService))
-			(.submit completion-service (solve-rule rule))))
+
-	; take the first result
+(declare start solve-goal solve-rule collect unify)
-	(if (= result 0.9)
+
-		result
+; Choose between using parallel collect or sequential collect.
-		(.get (.take completion-service))))
+(def use-parallel-collect true)
 
 (def completion-service (ExecutorCompletionService.
 	(Executors/newCachedThreadPool)))
 
 (defn start []
 	(print "Enter query: ") (flush)
 	(let [query (read-line)
 		  truth (solve-goal (symbol query))]
 		(printf "Answer is: %s\n" truth)))
 
 (defn fetch-rules [goal]
 	(case goal
 		g '[[a,b,c],[d,e,f]]
 		a '[[]]
 		b '[[]]
 		c '[[]]
 		d '[[]]
 		e '[[]]
 		f '[[]]
 		true (throw (Exception. "No applicable rules"))))
 
 (defn solve-goal [goal]
 	(let [rules (fetch-rules goal)]
 		(if (some empty? rules)
 			1.0		; return a truth value
 			(do
 				(doseq [rule rules]
 					(.submit completion-service (solve-rule rule)))
 				(.get (.take completion-service))))))
 
 ; Move minimization logic here from collect.
 (defn solve-rule [rule-tail]
 	(let [truths (collect solve-goal rule-tail)]
 		(apply min truths)))
 
 ; Accumulate results
 (def collect (if use-parallel-collect pmap map))