tisp

commit 6c19b7d5ebce15e627069f23316023ec15b38575
parent 97f1ccbe65c361638b09a655691b95f9de2c25cb
Author: Ed van Bruggen <edvb@uw.edu>
Date:   Fri,  6 Sep 2019 16:34:54 -0700

Add list boolean functions empty? cons? and pair?

Diffstat:
tibs/lib.tsp
 | 
3
+++

1 file changed, 3 insertions(+), 0 deletions(-)
diff --git a/tibs/lib.tsp b/tibs/lib.tsp
@@ -33,6 +33,7 @@
 ;;; Types
 (define (void? x)      (= (type x) "void"))
 (define (nil? x)       (= (type x) "nil"))
+(define  empty?         nil?)
 (define (integer? x)   (= (type x) "integer"))
 (define (decimal? x)   (= (type x) "decimal"))
 (define (ratio? x)     (= (type x) "ratio"))
@@ -41,6 +42,8 @@
 (define (primitive? x) (= (type x) "primitive"))
 (define (function? x)  (= (type x) "function"))
 (define (pair? x)      (= (type x) "pair"))
+(define  cons?          pair?)
+(define (list? x)      (and (pair? x) (pair? (cdr x))))
 (define (boolean? x)   (or (= x t) (nil? x)))
 (define (true? x)      (= x t))
 (define  false?         nil?)