An example of filtering out definitions in a language

example-lang.rkt

#lang racket
(require racket/provide
         (prefix-in racket: racket))
(define count 'count)
(provide (except-out 
          (filtered-out (lambda (name)
                          (and (regexp-match? #rx"^racket:" name)
                               (regexp-replace #rx"^racket:" name "")))
                        (all-from-out racket))
          racket:count)

         count)

(module* main (submod "..")
  (displayln count))