solution to 1.32

diff --git a/src/sicp/ex1_32.clj b/src/sicp/ex1_32.clj
new file mode 100644 (file)
index 0000000..369b677
--- /dev/null
+++ b/src/sicp/ex1_32.clj
@@ -0,0 +1,47 @@
+(ns sicp.ex1_32
+  (:use [sicp utils]
+       [clojure.contrib test-is]))
+
+(defn accumulate [combiner null-value term a next b]
+  (if (> a b)
+    null-value
+    (combiner (term a)
+             (accumulate combiner null-value term (next a) next b))))
+
+(def sum (fn [a b] (accumulate + 0 identity a inc b)))
+
+(def sum-cube (fn [a b] (accumulate + 0 cube a inc b)))
+
+(def prod (fn [a b] (accumulate * 1 identity a inc b)))
+
+(defn iaccumulate [combiner null-value term a next b]
+  (iter combiner null-value term a next b null-value))
+
+(defn iter [combiner null-value term a next b result]
+  (if (> a b)
+    result
+    (iter combiner null-value term (next a) next b (combiner (term a) result))))
+
+(deftest test-sum-of-integers-from-1-to-10
+  (is (= (sum 1 10) (reduce + (range 1 11)))))
+
+(deftest test-sum-cube-of-integers-from-1-to-10
+  (is (= (sum-cube 1 10) (reduce + (map cube (range 1 11))))))
+
+(deftest test-prod-of-ints-from-1-to-10
+  (is (= (prod 1 10) (reduce * (range 1 11)))))
+
+(def isum (fn [a b] (iaccumulate + 0 identity a inc b)))
+
+(def isum-cube (fn [a b] (iaccumulate + 0 cube a inc b)))
+
+(def iprod (fn [a b] (iaccumulate * 1 identity a inc b)))
+
+(deftest test-isum-of-integers-from-1-to-10
+  (is (= (isum 1 10) (reduce + (range 1 11)))))
+
+(deftest test-isum-cube-of-integers-from-1-to-10
+  (is (= (isum-cube 1 10) (reduce + (map cube (range 1 11))))))
+
+(deftest test-iprod-of-ints-from-1-to-10
+  (is (= (iprod 1 10) (reduce * (range 1 11)))))