Add lab and quiz contents

labs/L07/short-circuit.rkt

@@ -0,0 +1,28 @@
+#lang racket
+(define-syntax-rule (And a b)
+  (if b a #f))
+
+(module+ test
+  (require rackunit)
+  (define (die)
+    (error 'die "don't run this"))
+
+  (check-equal? (And (die) #f) #f)
+  (check-exn exn:fail? (lambda () (and (die) #f))))
+
+(module+ test
+  (define-syntax-rule (check-fail expr)
+    (check-exn exn:fail? (lambda () expr)))
+  (check-fail (and (die) #f))
+  (check-fail (And #f (die))))
+
+(define-syntax-rule (Or a b)
+  (or b a))
+  ;(if (not a) b #t))
+
+(module+ test
+  (check-equal? (Or #t #t) #t)
+  (check-equal? (Or #f #t) #t)
+  (check-equal? (Or #t #f) #t)
+  (check-equal? (Or (die) #t) #t)
+  (check-fail (or (die) #t)))