#!r6rs
(library (distinct)
         (export distinct?)
         (import (rnrs))

(define (distinct? eq? items)
  (if (null? items) #t
      (let* ((first (car items))
             (rest (cdr items)))
        (cond
          ((or (exists (lambda (i) (eq? first i)) rest)
               (not (distinct? eq? rest))) #f)
          (else #t)))))

)