tisp

commit 606233e93e498cd6a0ca72c5684eb09ff3c2bdf2
parent 6b3cf4de18170e95508c2ad8a33e2265abaf4e72
Author: Ed van Bruggen <edvb@uw.edu>
Date:   Fri, 27 Sep 2019 18:32:54 -0700

Use cons? to check if a value is a single cons

Diffstat:
tibs/lib.tsp
 | 
2
+-

1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tibs/lib.tsp b/tibs/lib.tsp
@@ -43,7 +43,7 @@
 (define (function? x)  (= (type x) "function"))
 (define (macro? x)     (= (type x) "macro"))
 (define (pair? x)      (= (type x) "pair"))
-(define  cons?          pair?)
+(define (cons? x)      (and (pair? x) (not (pair? (cdr x)))))
 (define (list? x)      (and (pair? x) (pair? (cdr x))))
 (define (boolean? x)   (or (= x t) (nil? x)))
 (define (true? x)      (= x t))