Add tests for 3.56

resources/views/exercise/solution_stub/3_56.blade.php

@@ -0,0 +1,58 @@
+#lang sicp
+(#%require rackunit)
+
+
+;;; BEGIN
+{!! $solution !!}
+;;; END
+
+(define (stream-car stream) (car stream))
+
+(define (stream-cdr stream) (force (cdr stream)))
+
+(define (stream-map proc . list-of-stream)
+    (if (null? (car list-of-stream))
+        '()
+        (cons-stream
+            (apply proc 
+                   (map (lambda (s)
+                            (stream-car s))
+                        list-of-stream))
+            (apply stream-map 
+                   (cons proc (map (lambda (s)
+                                       (stream-cdr s))
+                                   list-of-stream))))))
+
+(define (scale-stream stream factor)
+  (stream-map (lambda (x) (* x factor)) stream))
+
+(define (merge s1 s2)
+  (cond ((stream-null? s1) s2)
+        ((stream-null? s2) s1)
+        (else
+         (let ((s1car (stream-car s1))
+               (s2car (stream-car s2)))
+           (cond ((< s1car s2car)
+                  (cons-stream s1car (merge (stream-cdr s1) s2)))
+                 ((> s1car s2car)
+                  (cons-stream s2car (merge s1 (stream-cdr s2))))
+                 (else
+                  (cons-stream s1car
+                               (merge (stream-cdr s1)
+                                      (stream-cdr s2)))))))))
+
+
+(define scar stream-car)
+(define scdr stream-cdr)
+
+
+(check-equal? (scar s) 1)
+(check-equal? (scar (scdr s)) 2)
+(check-equal? (scar (scdr (scdr s))) 3)
+(check-equal? (scar (scdr (scdr (scdr s)))) 4)
+(check-equal? (scar (scdr (scdr (scdr (scdr s))))) 5)
+(check-equal? (scar (scdr (scdr (scdr (scdr (scdr s)))))) 6)
+(check-equal? (scar (scdr (scdr (scdr (scdr (scdr (scdr s))))))) 8)
+(check-equal? (scar (scdr (scdr (scdr (scdr (scdr (scdr (scdr s)))))))) 9)
+(check-equal? (scar (scdr (scdr (scdr (scdr (scdr (scdr (scdr (scdr s))))))))) 10)
+(check-equal? (scar (scdr (scdr (scdr (scdr (scdr (scdr (scdr (scdr (scdr s)))))))))) 12)