with-slot syntax how to

["Marco Maggi" <marco.maggi-ipsu@poste.it>]

Ciao,
  in my quest for learning how to write syntaxes
I tried to write a WITH-SLOTS, getter only
version. I was not able to write it with SYNTAX-RULES only,
My better result so far is the dirty:

(define-module (hurt-me)
  #:use-module (ice-9 syncase)
  #:use-module (oop goops)
  #:duplicates merge-generics)


(define-macro (gee-p-with-slots ?bindings . ?forms)
  (let ((result ?forms))
    (for-each (lambda (object-bindings)
		(set! result `((with-slots ,object-bindings ,@result))))
      ?bindings)
    (car result)))

(define-syntax with-slots
  (syntax-rules ()
    ((_ (() ?object) ?form ...)
     (begin ?form ...))

    ;; only one parens level in the 'with-slots' first arg
    ((_ ((?sym ...) (?slot ...) ?object) ?form ...)
     (let ((?sym (slot-ref ?object '?slot))
	   ...)
       ?form ...))

    ;; two parens level in the 'with-slots' first arg
    ((_ (((?sym ...) (?slot ...) ?object)) ?form ...)
     (let ((?sym (slot-ref ?object '?slot))
	   ...)
       ?form ...))

    ((_ (((?sym ...) (?slot ...) ?object) ...) ?form ...)
     (gee-p-with-slots (((?sym ...) (?slot ...) ?object)
...) ?form ...))))

(define-class <C> ()
  (a #:init-keyword #:a)
  (b #:init-keyword #:b)
  (c #:init-keyword #:c))

(define A (make <C>
	    #:a 1 #:b 2 #:c 3))
(define B (make <C>
	    #:a 4 #:b 5 #:c 6))

(with-slots (((d e f) (a b c) A)
	     ((g h i) (a b c) B))
  (write (list d e f g h i)))

is it even possible to write it with SYNTAX-RULES only?

--
Marco Maggi

"Now feel the funk blast!"
Rage Against the Machine - "Calm like a bomb"




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