Add 1.32

sicp-ex-1.32.rkt

@@ -0,0 +1,35 @@
+#! /usr/bin/racket
+#lang racket/base
+
+(define (accumulate-iter combiner null-value term a next b)
+  (define (iter a result)
+    (if (> a b)
+        result
+        (iter (next a) (combiner (term a) result))))
+  (iter a null-value))
+
+(define (product-iter term a next b)
+  (accumulate-iter * 1 term a next b))
+
+(define (sum-iter term a next b)
+  (accumulate-iter + 0 term a next b))
+
+(sum-iter (lambda (x) x) 1 (lambda (x) (+ x 1)) 4)
+(product-iter (lambda (x) x) 1 (lambda (x) (+ x 1)) 4)
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(define (accumulate-recur combiner null-value term a next b)
+  (if (> a b)
+      null-value
+      (combiner (term a)
+                (accumulate-recur combiner null-value term (next a) next b))))
+
+(define (product-recur term a next b)
+  (accumulate-recur * 1 term a next b))
+
+(define (sum-recur term a next b)
+  (accumulate-recur + 0 term a next b))
+
+(sum-recur (lambda (x) x) 1 (lambda (x) (+ x 1)) 4)
+(product-recur (lambda (x) x) 1 (lambda (x) (+ x 1)) 4)