gistfile1.scm

(use srfi-1)
(use slib)
(require 'format)

(define (arabic->roman n) (if (< 0 n 4000) (format "~@R" n) (error "oob")))
(define roman->arabic
  (let1 tab (map (^n `(,(format "~@R" n) . ,n)) (iota 3999 1))
    (^r (cond [(assoc r tab string-ci=?) => cdr] [else (error "huh?")]))))