Uri Guttman <[EMAIL PROTECTED]> writes:
>>>>>> "DS" == Dan Sugalski <[EMAIL PROTECTED]> writes:
>
> >> Correct, especially a list is nothing but a pair with another pair or
> >> an end-of-list-marker in its second element. To implement set-car! and
> >> set-cdr! both elements of this pair must be mutable
>
> DS> Hmmm. I think we can use one thing for both perl pairs and scheme
> DS> pairs. We'll need to be careful in spots, though. Perl pairs must
> DS> have scalars on either side. (Just as arrays and hashes can only hold
> DS> scalars, not arrays or hashes or lists)
>
> but lisp dotted pair actually only can hold scalars in each node
> too. each node could be a pointer to other stuff or a value. that is
> classic lisp data structures, all things are trees or lists made from
> pairs.
Unless I'm completely misunderstanding the lisp refs I've been reading
recently, a scheme pair is restricted to holding pointers. Either to
other pairs or to things. If you represent it as an array, then you
can have:
[\"string", $next_pair is reference]
but you couldn't have:
["car", $cdr is referent]
But I could be *way* off the mark there.
--
Piers
"It is a truth universally acknowledged that a language in
possession of a rich syntax must be in need of a rewrite."
-- Jane Austen?
