Add tests for 3.59

resources/views/exercise/solution_stub/3_59.blade.php

@@ -0,0 +1,60 @@
+#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 (mul-streams s1 s2)
+    (stream-map * s1 s2))
+
+(define (div-streams s1 s2)
+    (stream-map / s1 s2))
+
+(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 (scale-stream stream factor)
+  (stream-map (lambda (x) (* x factor)) stream))
+
+(define double (cons-stream 1 (scale-stream double 2)))
+
+(define scar stream-car)
+(define scdr stream-cdr)
+
+(define s (integrate-series double))
+
+(check-equal? (scar s) 1)
+(check-equal? (scar (scdr s)) 1)
+(check-equal? (scar (scdr (scdr (scdr s)))) 2)
+(check-equal? (scar (scdr (scdr (scdr (scdr (scdr (scdr (scdr s)))))))) 16)
+
+(check-equal? (stream-car sine-series) 0)
+(check-equal? (stream-car (stream-cdr sine-series)) 1)
+(check-equal? (stream-car (stream-cdr (stream-cdr sine-series))) 0)
+(check-equal? (stream-car cosine-series) 1)
+(check-equal? (stream-car (stream-cdr cosine-series)) 0)
+(check-equal? (stream-car (stream-cdr (stream-cdr cosine-series))) -1/2)