From 37ef9d09a8dea58516b343d130bc9b0d501b0d02 Mon Sep 17 00:00:00 2001
From: Ian Dees <undees@gmail.com>
Date: Tue, 9 Dec 2008 12:39:06 -0800
Subject: [PATCH] Examples in Clojure-spec format

---
 2008-12-5/examples.clj | 55 +++++++++++++++++++++---------------------
 1 file changed, 28 insertions(+), 27 deletions(-)

diff --git a/2008-12-5/examples.clj b/2008-12-5/examples.clj
index 3062e87..1bba37a 100644
--- a/2008-12-5/examples.clj
+++ b/2008-12-5/examples.clj
@@ -1,31 +1,37 @@
 (use 'primitive-recursive)
+(use 'clojure.spec)
 
 (def add (p-r (p 1 1) (o s (p 3 2))))
 
-(println (format "2 + 3 = %d" (add 2 3)))
+(defspec add
+  ([2 3] (= value 5)))
 
 (def multiply (p-r z (o add (p 3 2) (p 3 3))))
 
-(println (format "4 * 5 = %d" (multiply 4 5)))
+(defspec multiply
+  ([4 5] (= value 20)))
 
 (def if-then-else (p-r (p 2 2) (p 4 3)))
 
-(println (format "if 0 then 6 else 7 = %d" (if-then-else 0 6 7)))
-(println (format "if 1 then 6 else 7 = %d" (if-then-else 1 6 7)))
+(defspec if-then-else
+  ([0 6 7] (= value 7))
+  ([1 6 7] (= value 6)))
 
 (def logical-or (o if-then-else (p 2 1) (p 2 1) (p 2 2)))
 
-(println (format "0 or 0 = %d" (logical-or 0 0)))
-(println (format "0 or 1 = %d" (logical-or 0 1)))
-(println (format "1 or 0 = %d" (logical-or 1 0)))
-(println (format "1 or 1 = %d" (logical-or 1 1)))
+(defspec logical-or
+  ([0 0] (= value 0))
+  ([0 1] (= value 1))
+  ([1 0] (= value 1))
+  ([1 1] (= value 1)))
 
 (def logical-and (o if-then-else (p 2 1) (p 2 2) (p 2 1)))
 
-(println (format "0 and 0 = %d" (logical-and 0 0)))
-(println (format "0 and 1 = %d" (logical-and 0 1)))
-(println (format "1 and 0 = %d" (logical-and 1 0)))
-(println (format "1 and 1 = %d" (logical-and 1 1)))
+(defspec logical-and
+  ([0 0] (= value 0))
+  ([0 1] (= value 0))
+  ([1 0] (= value 0))
+  ([1 1] (= value 1)))
 
 (defn exists [pred]
   (p-r z (o logical-or (o pred (p 2 1)) (p 2 2))))
@@ -33,23 +39,18 @@
 (defn for-all [pred]
   (p-r (o s z) (o logical-and (o pred (p 2 1)) (p 2 2))))
 
+;; Predicates to throw at exists and for-all
 (def negative z) ; false for all n in N, by inspection
-
 (def logical-not (o if-then-else (p 1 1) z (o s z)))
-
 (def non-negative (o logical-not negative))
-
 (def even (p-r (o s z) (o logical-not (p 2 2))))
 
-(println (format "Some x < 10 is negative? %d"
-         ((exists negative) 10)))
-(println (format "All x < 10 are negative? %d"
-         ((for-all negative) 10)))
-(println (format "Some x < 10 is non-negative? %d"
-         ((exists non-negative) 10)))
-(println (format "All x < 10 are non-negative? %d"
-         ((for-all non-negative) 10)))
-(println (format "Some x < 10 is even? %d"
-         ((exists even) 10)))
-(println (format "All x < 10 are even? %d"
-         ((for-all even) 10)))
+(defspec exists
+  ([negative]     (= (value 10) 0))
+  ([non-negative] (= (value 10) 1))
+  ([even]         (= (value 10) 1)))
+
+(defspec for-all
+  ([negative]     (= (value 10) 0))
+  ([non-negative] (= (value 10) 1))
+  ([even]         (= (value 10) 0)))