ip-to-long.ss

#lang mzscheme

(require srfi/1/list
  srfi/14/char-set
  srfi/13/string)

(define ip-to-long
  (lambda (ip-as-string)
    (apply +
      (map *
        (map string->number (string-tokenize ip-as-string (string->char-set “0123456789″)))
        (map (lambda (x) (expt 256 x)) (iota 4 3 -1))))))

(define long-to-ip
  (lambda (ip-as-long)
    (string-join
      (map
        number->string
        (unfold-right
          zero?
          (lambda (x) (remainder x 256))
          (lambda (x) (quotient x 256))
          ip-as-long))
      “.”)))