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On Fri, 10 Dec 2004, Felix Winkelmann wrote:
Andre van Tonder wrote:On Fri, 10 Dec 2004, Felix Winkelmann wrote:From what my experiments show the current SRFI-57 reference implementationdoes *not* work on systems that provide a non-generative SRFI-9, or non- generative native records.I'm not sure why that should be. Would you mind saying a bit more on this?Here a simple implementation of SRFI-9, using syntax-case: [code snipped]
Hi Felix,The following modification of your code works, but is generative, and so probably misses the point of what you were trying to achieve. To get nongenerativity, the underlying SRFI-9-like interface should probably be passed an extra identifier to be used as tag, instead of creating a unique tag as done below.
Regards Andre (define <record> (list 'vector)) (define-syntax (srfi-9:define-record-type x) (define (memi id ids) (and (not (null? ids)) (or (free-identifier=? id (car ids)) (memi id (cdr ids)) ) ) ) (syntax-case x () [(_ t (conser vars ...) pred slots ...) (syntax-case #'(slots ...) () [((slotnames . _) ...) (with-syntax ([(slotvars ...) (map (lambda (sname) (if (memi sname #'(vars ...)) sname #'(void) ) ) #'(slotnames ...)) ] ) (with-syntax ([(accforms ...) (let loop ([slots #'(slots ...)] [i 2]) (if (null? slots) #'() (with-syntax ([ii i][(rest ...) (loop (cdr slots) (+ 1 i))] )
(syntax-case (car slots) () [(name get set) #'((define (get x) (vector-ref x ii) ) (define (set x y) (vector-set! x ii y) ) rest ...) ] [(name get) #'((define (get x) (vector-ref x ii) ) rest ...) ] ) ) ) ) ] ) #'(begin (define generated-tag (cons #f #f))(define (conser vars ...) (vector <record> generated-tag slotvars ...))
(define (pred x) (and (vector? x) (eq? <record> (vector-ref x 0))(eq? generated-tag (vector-ref x 1))))
accforms ...) ) ) ] ) ] ) )