0. #lang typed/racket
1. (require typed/racket/unsafe)
2.  
3. (module untyped racket
4.   (provide maybe-car)
5.   (define (maybe-car x)
6.     (cond
7.       [(pair? x) (car x)]
8.       [else x])))
9.  
10. (unsafe-require/typed
11.  'untyped
12.  [maybe-car (All (a b) (case->
13.                         (-> (Pairof a b) a)
14.                         (-> a a)))])
15.  
16. (maybe-car (cons 'foo 'bar))
17. (maybe-car 94)

=>

eval:2:0: ?: access disallowed by code inspector to

protected transformer

from module: "/home/pasterack/racket73/share/pkgs/typed-ra

cket-lib/typed/racket/unsafe.rkt"

at: unsafe-require/typed

eval:3:0: Type Checker: missing type for top-level

identifier;

either undefined or missing a type annotation

identifier: maybe-car

in: bar

eval:4:0: Type Checker: missing type for top-level

identifier;

either undefined or missing a type annotation

identifier: maybe-car

in: 94