Fix failed unit tests

Author: ramsayleung

chapter3/exercise3-69.rkt

@@ -16,22 +16,33 @@
 (define (square x)
   (* x x))
 
-(define (pythagorean)
+(define (pythagorean triple-stream)
   (stream-filter (lambda (triple)
                    (= (+ (square (car triple))
                          (square (cadr triple)))
                       (square (caddr triple))))
-                 (triples integers integers integers)))
+                 triple-stream))
 (module+ test
   (require rackunit)
 
   (test-case "Test for triples"
              (define s1 (list-to-stream '(1 2 3)))
              (define s2 (list-to-stream '(1 2 3)))
              (define s3 (list-to-stream '(1 2 3)))
-             (check-equal? (stream-to-list (triples s1 s2 s3) 10) '((1 1 1) (1 1 2) (2 2 2) (1 2 2) (2 2 3)))
-             )
-  (test-case "Test for pythagorean"
-             (check-equal? (stream-to-list (pythagorean) 2) '((3 4 5) (6 8 10)))
-             )
-  )
+             (check-equal? (stream-to-list (triples s1 s2 s3) 20) '((1 1 1)
+                                                                    (1 1 2)
+                                                                    (2 2 2)
+                                                                    (1 2 2)
+                                                                    (2 2 3)
+                                                                    (1 1 3)
+                                                                    (3 3 3)
+                                                                    (1 2 3)
+                                                                    (2 3 3)
+                                                                    (1 3 3)))
+             (test-case "Test for pythagorean"
+                        (define s1 (stream-enumerate-interval 1 10))
+                        (define s2 (stream-enumerate-interval 1 10))
+                        (define s3 (stream-enumerate-interval 1 10))
+                        (check-equal? (stream-to-list (pythagorean (triples s1 s2 s3)) 2) '((3 4 5) (6 8 10)))
+                        )
+             ))

chapter3/infinite-stream.rkt

@@ -32,10 +32,8 @@
 (define (interleave s1 s2)
   (if (stream-null? s1)
       s2
-      (if (stream-null? s2)
-          the-empty-stream
-          (cons-stream (stream-car s1)
-                       (interleave s2 (stream-cdr s1))))))
+      (cons-stream (stream-car s1)
+                   (interleave s2 (stream-cdr s1)))))
 
 (define (pairs s t)
   (if (or (stream-null? s) (stream-null? t))