(provide
  (contract-out
    #:forall A
    #:forall B
    [map (-> (-> A B) (listof A) (listof B))]))
(define (map f l)
  (match l
    [(list) empty]
    [(list h t ...) (cons h (map f t))])) ; <- Error should break internal contract by simply cons-ing h.


(map (lambda (x) 10) (list "foo" "bar"))