#;
(exn-pred 7)
#lang typed/scheme
(require racket/unsafe/ops)

(define-struct: foo ((x : Integer) (y : String)))
(define-struct: (bar foo) ((z : Float)))

(define a (make-foo 1 "1"))
(define b (make-bar 2 "2" 2.0))

(+ (unsafe-struct-ref a 1) 2)
(+ (unsafe-struct-ref b 1) 2)

(unsafe-struct-set! a 0 "2")
(unsafe-struct-set! a 1 2)
(unsafe-struct-set! b 0 3.0)
(unsafe-struct-set! b 1 3)
(unsafe-struct-set! b 2 "3")