fogus · December 21, 2009 20:32
diff --git a/gistfile1.clj b/gistfile1.clj

 (defn constrained-fn [f x]
    {:pre  [(pos? x)]
     :post [(= % (* 2 x))]}
    (f x))

 (constrained-fn #(* 2 %) 2)
 ;=> 4
 (constrained-fn #(float (* 2 %)) 2)
 ;=> 4.0
 (constrained-fn #(* 3 %) 2)
 ;=> java.lang.Exception: Assert failed: (= % (* 2 x))

	(defn constrained-fn [f x]
	{:pre [(pos? x)]
	:post [(= % (* 2 x))]}
	(f x))

	(constrained-fn #(* 2 %) 2)
	;=> 4
	(constrained-fn #(float (* 2 %)) 2)
	;=> 4.0
	(constrained-fn #(* 3 %) 2)
	;=> java.lang.Exception: Assert failed: (= % (* 2 x))