;; record.scm

;; from SRFI 9

(define-syntax define-record-type
  (syntax-rules ()
    ((define-record-type type
                         (constructor constructor-tag ...)
                         predicate
                         (field-tag accessor . more) ...)
     (begin
       (define type
         (make-record-type 'type '(field-tag ...)))
       (define constructor
         (record-constructor type '(constructor-tag ...)))
       (define predicate
         (record-predicate type))
       (define-record-field type field-tag accessor . more)
       ...))))

; An auxilliary macro for define field accessors and modifiers.
; This is needed only because modifiers are optional.

(define-syntax define-record-field
  (syntax-rules ()
    ((define-record-field type field-tag accessor)
     (define accessor (record-accessor type 'field-tag)))
    ((define-record-field type field-tag accessor modifier)
     (begin
       (define accessor (record-accessor type 'field-tag))
       (define modifier (record-modifier type 'field-tag))))))

;;;;;;;;;;;;;;;;;;;;;;

(define-record-type test
  (make-test a b)
  test?
  (a  get-a set-a)
  (b  get-b set-b))

(define t (make-test 1 2))

(display t)(newline)
(display (get-a t))(newline)