I just found this today:
#lang typed/racket
(define: b : (Boxof Any) (box 4))
(define-predicate boxof-integer? (Boxof Integer))
(define (set-b-box! v) (set-box! b v))
(: a-very-listy-integer (-> Integer))
(define (a-very-listy-integer)
(cond [(boxof-integer? b) (set-b-box! '(1 2 3))
(unbox b)]
[else (error 'a-very-listy-integer "can't happen")]))
> (a-very-listy-integer)
- : Integer
'(1 2 3)
Is this a bug or a limitation? It can be replicated with any mutable
container type as far as I can tell.
Also, if it's a limitation, can I get (Vectorof Index) to be a subtype
of (Vectorof Integer)?
Neil ⊥
_________________________
Racket Developers list:
http://lists.racket-lang.org/dev
