In the last line split&flip receives 0, but it needs a pair. The following wotks correct: #lang racket/base (define (split&flip xy) (define-values (x y) (values (car xy) (cdr xy))) (values y x)) ;; My mistake: x should be a pair
(define-values (a b) (split&flip (cons 0 1))) (cons a b) ; -> (1 . 0) In this case I don't see a fault in racket/base Jos _____ From: [email protected] [mailto:[email protected]] On Behalf Of Benjamin Greenman Sent: domingo, 13 de septiembre de 2015 7:58 To: Racket Users Subject: [racket-users] values considered harmful Something bad happened. I was using values and pairs, made a small mistake, and wound up with a segfault (on v6.2 and v6.2.900.16). Here's a minimal example: #lang racket/base (define (split&flip xy) (define-values (x y) (values (car xy) (cdr xy))) (values y x)) ;; My mistake: x should be a pair (define-values (a b) (split&flip (cons 0 1))) (split&flip b) What's really strange to me is that many versions of this program raise the expected "car: contract violation" error. For example, try changing the buggy line to `(values x y)` or `(values x x)` or even `(values (+ y) (+ x))`. -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
