Re: Double unquote/unquote-splicing

[Stefan Monnier]

> In fact, I just built from trunk with two lines of code from
> backquote.el changed (using your helpful comments), and it seems to work
> precisely like that.  In other words, this doesn't seem to require any
> extra work.

I know (obviously), but I rather dislike this weird intermediate state,
which doesn't fit cleanly in the usual semantics of unquote (whose
special syntax makes it clear that it's supposed to have just one
argument).

The fact that Common-Lisp found a way to extend the semantics in a way
that makes some sense is fine for Common-Lips, but not enough to
convince me.

Your example was the first concrete example I've seen where such
a ,,@foo construct was used and as you've seen it's trivially replaced
by ,@(list ,@foo) (which is true because ,foo is equivalent to ,@(list
foo).

So ,,@ is not a very compelling use.  Maybe ,@,@ would be more
compelling, but I haven't seen any concrete use for it yet, so
I can't comment.


        Stefan