push by kqh

solutions/chap2/code/exercise2-33.rkt

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+#lang sicp
+;; We use a conventonal name: Reduce to redefine the accumlate process
+(define (reduce op init items) 
+          (cond ((null? items) init)
+                (else (op (car items) 
+                          (reduce op init (cdr items))))))
+
+;; We reduce-map to indicate this version of map is implemented by reduce
+;; Same for append and length
+(define (reduce-map p items) 
+    (reduce (lambda (x y) (append (list (p x)) y)) nil items))
+(reduce-map (lambda (x) (+ x 1)) (list 1 2 3))
+(reduce-map (lambda (x) (* x x)) (list 1 2 3))
+
+(define (reduce-append seq1 seq2)
+  (reduce (lambda (x y) (cons x y)) seq2 seq1))
+
+(reduce-append (list 1 2 3) (list 4 5 6))
+
+(define (reduce-length seq) 
+  (reduce (lambda (x y) (+ 1 y)) 0 seq))
+
+(reduce-length (list 1))
+