racket/collects/scribblings/guide/contracts-examples/ho-version1.rkt
2011-09-24 22:30:56 +09:00

25 lines
760 B
Racket

#lang racket/load
(module a racket/base
(require racket/contract (only-in racket/list first second rest empty?) (prefix-in old: (only-in racket/list argmax)))
(define (argmax f lov)
(old:argmax f lov))
(provide
(contract-out
[argmax (-> (-> any/c real?) (and/c pair? list?) any/c)])))
(module b racket/base
(require 'a)
(require racket/contract/private/blame)
(with-handlers ([exn:fail:contract:blame? void])
(printf "***0: ~s\n" (argmax car '())))
(with-handlers ([exn:fail:contract:blame? void])
(printf "***1: ~s\n" (argmax car '())))
(with-handlers ([exn:fail:contract:blame? void])
(printf "***2: ~s\n" (argmax car '((apples 3)))))
(printf "3: ~s\n" (argmax car '((3 apples) (3 oranges)))))
(require 'b)