tomas@tuxteam.de writes:

> Curiously, Jan (also in this thread) came up with "clone",
> independently.

Yes you're right. :)

Speaking of Jan and I both thinking about clone'ish things, we did a bit
of talking on IRC and I think we have a very nice version of functional
setters where you can "clone" multiple fields at the same time.

Here's what it looks like in practice, adapting from the
(srfi srfi-9 gnu) code:

  (define fsf-address
    (make <address>
      #:street "Franklin Street"
      #:city "Boston"
      #:country "USA"))

  (define rms
    (make <person>
      #:age 30
      #:email "rms@gnu.org"
      #:address fsf-address))

  (define new-rms
    (clone rms
           ((.age) 60)
           ((.address .street) "Temple Place")))

  scheme@(guile-user)> (.age rms)
  $12 = 30
  scheme@(guile-user)> (.age new-rms)
  $13 = 60
  scheme@(guile-user)> (.street (.address rms))
  $14 = "Franklin Street"
  scheme@(guile-user)> (.street (.address new-rms))
  $15 = "Temple Place"

... not bad, eh?

Updated copy of goops-functional-setter.scm attached!  What do other
people think?  Should I try to get this upstream in Guile?