gistfile1.rkt

#lang racket
(require (for-syntax racket racket/syntax))

(provide (all-defined-out))

(define-syntax (struct* stx)
  (syntax-case stx ()
    ((_ name (args ...) (defaults ...) others ...)
     (with-syntax ((arg-list (datum->syntax #'(args ...)
                                            (for/list ((arg (syntax->list #'(args ...)))
                                                       (default (syntax->datum #'(defaults ...))))
                                              (if (not (eq? '_ default))
                                                  (list arg default)
                                                  arg))))
                   (real-constructor (format-id #'name "make-~a" #'name)))
       (displayln #'real-constructor)
       #'(begin (struct name (args ...) #:constructor-name constructor others ...)
                (define (real-constructor . arg-list)
                  (constructor args ...)))))))

(struct* posn (x y z) (_ 0 1) #:transparent)