chickadee » record-vector » rv-update!

These procedure and macro (which recursive variant) for update existing attribute values ​​and add new attribute in record-vector R-V.

 
> (define p (make-rv posn: (make-rv x: 1 y: 2)))
> (rv-update! p posn: x: 10)
> p => (((#:posn . 0)) . #((((#:x . 0) (#:y . 1)) . #(10 2))))
> (rv-update! p posn: z: 30)
> p => (((#:posn . 0)) . #((((#:x . 0) (#:y . 1) (#:z . 2)) . #(10 2 30))))
;; rv-update! is stable
> (rv-update! p posn: z: 30)
> p => (((#:posn . 0)) . #((((#:x . 0) (#:y . 1) (#:z . 2)) . #(10 2 30))))