anchor.diff:           (= (aref arr ,index) val)))))
   
   (defun %struct-getters (name fields)
  -  (let index 0
  +  (let index 1
       (mapcar [%struct-single-get name (%struct-field-name _) (1+! index)] fields)))
  +
  +(defun struct? (x)
  +  (& (array? x)
  +     (eq 'struct (aref x 0))))
   
   (defun %struct? (name)
     (let sym (%struct?-symbol name)
  -    `(defun ,sym (arr)
  -       (& (array? arr)
  -          (eq ',name (aref arr 0))))))
  +    `(defun ,sym (x)
  +       (& (struct? x)
  +          (eq ',name (aref x 1))))))
   
   (defun %struct-sort-fields (fields-and-options)
     (with-queue (fields options)
  
positive.code: 				   fields)))
  
  (defun %struct-make-init (fields g)
    (let index 0
      (mapcar [let argname (%struct-field-name _)
                `(= (aref ,g ,(1+! index))
  				  (? (eq ,argname ',argname)
  				     ,(& (cons? _)
  						 (cadr _))
  				     ,argname))]
              fields)))
  
  (defun %struct-make (name fields options)
    (with (sym (%struct-make-symbol name options)
  		 g (gensym)
           user-init (%struct-make-init fields g)
  	     type-init `((= (aref ,g 0) ',name)))
      `(defun ,sym ,(%struct-make-args fields)
         (let ,g (make-array ,(1+ (length fields)))
           ,@(? user-init
  	          (nconc type-init user-init)
  	          type-init)
  
negative.code: ;;;;; tré – Copyright (c) 2005–2009,2011–2013 Sven Michael Klose <pixel@copei.de>
  
  (defun %struct-option-keyword (e)
    (in? e :constructor))
  