Why don't people like lisp?

[prunesquallor at comcast.net]

Marcin 'Qrczak' Kowalczyk <qrczak at knm.org.pl> writes:

> On Fri, 24 Oct 2003 01:09:43 +0000, prunesquallor wrote:
>
>> You don't need to CPS convert everything because the backtracking
>> continuations are upwards only.
>
> I don't know what are upward continuations but it doesn't seem to be
> possible. Assume that during mapcar one lambda returns a choice, and
> some further lambda fails. How can macros cause mapcar to go back a few
> elements, without reimplementing mapcar? Does Common Lisp support some
> restricted kind of continuations?

CATCH and THROW are a restricted kind of continuation.  The only allow
transfer of control in one direction and the transfer can only take
place once.

If you are curious about how mapcar interacts, I suggest you download
the screamer package from 
    http://www.ece.purdue.edu/~qobi/software.html