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Re: [Scheme-reports] What happened to (UNQUOTE <expression> ...)
On Sat, Apr 23, 2011 at 11:09:34PM -0400, Andre van Tonder wrote:
> > It looks reasonable to me, but could you point us
> > to the discussions or rationales?
> > Specifically, how is (unquote-splicing a b c) different from
> > ,@a ,@b ,@c ?
> I think the issue is a little more complex that this, it has to do with the
> fact that nested unquote-splicing was accidentally broken in Scheme, but since I
> don't remember the details offhand, let me quote Al* Petrofsky on this issue.
Thank you for this rationale. I asked about the same issue before, but
that part of my message was ignored. I considered the R6RS change rather
unintuitive, but the case of unquoting to undo nested quoting levels for
one spliced unquote makes sense.
If this makes it into R7, I would like to see a rationale for this added.
I looked for one in R6 and couldn't find it in there. I think this is
necessary considering this is very strange behaviour: I compared it to
implicit splicing of MV into the calling expression. It still feels like
that to me, but at least now I understand why it's necessary or useful.
PS: Andre, could you please consider not replying to an earlier message
when posting a new, unrelated issue? This confuses mailclients with
threading support because the in-reply-to header contains the message ID
of the message you're replying to; this causes my mailclient to think all
your messages of today belong to one giant thread :(
It also messes up the archive's threaded view at
but the mailman software is broken in another way.
"The process of preparing programs for a digital computer
is especially attractive, not only because it can be economically
and scientifically rewarding, but also because it can be an aesthetic
experience much like composing poetry or music."
-- Donald Knuth
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