[plt-scheme] quasiquote?
Ken Anderson writes:
> I now see that args must be a list, which i assume means a proper list.
>
> At 11:37 AM 1/7/2004 -0500, Ken Anderson wrote:
> >> (define name 'sscanf)
> >> (define args '(string format-string . args))
> >> `(,name . ,args)
> >(sscanf string format-string . args)
> >> `(,name , at args)
> >. append: expects argument of type <proper list>; given (string format-string . args)
> >>
> >
> >>From my experience with Common Lisp i expected the two quasiquote expressions to print the same. Am i doing somethine wrong in Scheme or is this a bug?
> >I'm using 200alpha12 (iteration 0)
Coincidentally, I just ran into the same limitation: unquote-splicing
only works on proper lists. (Actually the one I ran into was
unsyntax-splicing.) R5RS only says its argument "must evaluate to a
list", but it doesn't say proper list-- or is this always implied by
the spec? Anyway, is there a good reason not to extend it to work on
improper lists as well?
Speaking of improper lists, I converted my code to use MzLib's
plt-match.ss instead of match.ss, and had to do some kludging to deal
with the separate "list" vs. "list-rest" patterns. Is there a good
reason to separate these, rather than just have a single "list"
pattern whose argument is allowed to be an improper list?
--dougo at place.org