My apologies if this has been asked and answered. I seem to recall it being discussed, but for the life of me I can't find a clear reference to it.
What is logic programming in Perl 6 expected to look like? Larry writes that he wants "logic programming to be one of the paradigms that Perl supports" (http://www.mail-archive.com/perl6-language@perl.org/msg08990.html). Will this be implemented via rules? I get hints of that reading through the Exegeses, but a concrete example that illustrates something I'm more familiar with would be nice. For example, let's say I want to perform the classic "append" operation from Prolog whereby I append list X and list Y to get list Z. (You can read more about this at http://www.perlmonks.org/?node_id=424075) append(X,Y,Z). 1. Given X and Y, we can infer Z. 2. Given Y and Z, we can infer X. 3. Given Z, we can infer all X and Y that could append to form Z. I get all of that from one definition of append and I don't have to tell the language how to find those results (if you know Prolog, hush. There's some hand-waving going on here). I'm trying to figure out how that works in Perl 6. The closest I can come up with for third example is this: my $append = rx:any/ (<alpha>*) { let $X := $1 } (<alpha>*) { let $Y := $2 } / while 'abcd' =~ $append { say "X is $0{X} and Y is $0{Y}"; } But I know that's probably far from correct. It also has problems. First, it only operates on strings. Second, I can't do all make all three examples work from the one regular expression. Is there more here that I am not seeing (I confess to not having paid close attention.) And feel free to correct my syntax. Cheers, Ovid ===== If this message is a response to a question on a mailing list, please send follow up questions to the list. Web Programming with Perl -- http://users.easystreet.com/ovid/cgi_course/
