#!r6rs

(import (rnrs)
        (for (distinct) expand))

(define-syntax assert-distinct
  (lambda (stx)
    (syntax-case stx ()
      ((_ args ...) (distinct? bound-identifier=? #'(args ...)) #'(args ...))
      ((_ args ...) (syntax-violation 'assert-distinct "Duplicate name" #'(args ...))))))

(assert-distinct a b)
(assert-distinct a a)