Implement till 3.66

ex-3_50-62.scm

@@ -34,15 +34,6 @@
 
 (display "\nex-3.51\n")
 
-(define (show x)
-  (display-line x)
-  x)
-
-(define (stream-ref s n)
-  (if (= n 0)
-      (stream-car s)
-      (stream-ref (stream-cdr s) (- n 1))))
-
 (define x (stream-map show (stream-enumerate-interval 0 10)))
 
 (stream-ref x 5)
@@ -59,9 +50,6 @@
 
 (display "\nex-3.52\n")
 
-(define (display-stream s)
-  (stream-for-each display-line s))
-
 (define sum 0)
 
 (define (accum x)
@@ -106,19 +94,10 @@
 
 (display "\nex-3.53\n")
 
-(define (add-streams s1 s2)
-  (stream-map + s1 s2))
-
 (define ones (cons-stream 1 ones))
 
 (define integers (cons-stream 1 (add-streams ones integers)))
 
-(define (take n xs)
-  (if (= n 0)
-    '()
-    (cons (stream-car xs)
-          (take (- n 1) (stream-cdr xs)))))
-
 (assert (take 3 integers)
         '(1 2 3))
 
@@ -131,9 +110,6 @@
 (assert (take 7 fibs)
         '(0 1 1 2 3 5 8))
 
-(define (scale-stream stream factor)
-  (stream-map (lambda (x) (* x factor)) stream))
-
 (define double (cons-stream 1 (scale-stream double 2)))
 
 (assert (take 3 double)