10 lines
194 B
Racket
10 lines
194 B
Racket
#lang typed/scheme
|
|
|
|
(define-predicate int-or-bool? (U Integer Boolean))
|
|
|
|
(int-or-bool? 7)
|
|
|
|
(define-predicate int-list? (Rec List (Pair Integer (U '() List))))
|
|
(int-list? 1)
|
|
(int-list? '(1 2 3))
|