Re: perl 6 hosting?
On 5/25/06, David Cantrell [EMAIL PROTECTED] wrote: I might be able to host a virtual machine with perl6 on it and give out accounts. I need to think about how to stop people being naughty though. Probably the easy part is to to remove the most dangerous calls such as eval and system and then chroot the users. The hard part is to make sure they won't write code to exploit other sites or create hug load on your machine... ... but if someone does it in Perl6 that might be a good sign of the maturity of Pugs. Ah and you could also declare that all the code uploaded to that server is automatically copyright Perl Foundation and can have a public log of it. Gabor
Fwd: eval
Oh try! I like that! But is CATCH implemented in pugs? Anyone care
to give a working example of try/CATCH?
--michael
On 25/05/06, Yuval Kogman [EMAIL PROTECTED] wrote:
To complement string eval with eval { } (now called try):
try {
die foo;
} or say error: $!
On Thu, May 25, 2006 at 01:08:42 +0100, Michael Mathews wrote:
This works...
#!/usr/bin/pugs
my $code = sqawk(;
eval $code or say $!;
say but still running.;
it prints out...
unexpected end of input
expecting comment, :, identifier, term or )
but still running.
On Wed, May 24, 2006 at 19:54:53 +0300, Gabor Szabo wrote:
if eval command fails, where can I get the error message ?
aka $@ in P5 ?
$!
Re: eval
Hi Michael,
On 5/24/06, Michael Mathews [EMAIL PROTECTED] wrote:
Oh try! I like that! But is CATCH implemented in pugs? Anyone care
to give a working example of try/CATCH?
I don't think CATCH is implemented in pugs yet:
#!/usr/local/bin/pugs
catcher;
sub catcher {
say here;
try {
fail_trying;
say tried;
CATCH {
say catch;
}
}
if $! {
say error;
}
say there;
}
sub fail_trying {
fail_ failed;
}
OUTPUT:
here
tried
error
there
I used fail_ instead of die because I saw it somewhere, but don't
really know the reason to use it instead of die. Anyway, hope that is
at least some help.
David
Perl 6 Wiki -- 2 more possibilities, further discussion.
(Responding to 3 notes on 2 mail lists here; Changed subject line.)
Juerd wrote:
Feather, the semi-public, semi-private, Perl 6 development server, is
available to host a Perl 6 wiki.
The hostname www.perl6.nl is deliberately kept available for something
like that.
Does that mean you are willing to be the one to set up a Perl 6 Wiki and
administer it? (Preferably using perl5 wiki software, so that the Perl 6
Wiki could be available as soon as possible?) If so, how much more
encouragement do you need to proceed?
From: Michael Mathews [mailto:[EMAIL PROTECTED]
As a competing suggestion, how about...
http://pugs.kwiki.org/?perl6
Very interesting. But did you look at it? :-) I found this on the home page
link target:
Consider using Subversion instead of this Wiki
20051213Z05:58 audreyt I'd like it [the wiki] to
be strictly a scratchpad for lambdacamels.
all reusable docs should be in the svn tree
(and now Perl6::Doc)
This reminds me of my earlier suggestion:
Could we use part of Pugs doc tree as alternative
to perl6-user-doc wiki?
http://www.nntp.perl.org/group/perl.perl6.users/28
The basic idea is this: since the pugs svn tree is mirrored at perl.org, we
could have a subdirectory (for example Perl_6_ Wiki) in the docs branch of
the source tree that would have a wiki-like hierarchy of html pages (or pod
pages for generating html) below it. The downside is that it would take
somewhat more effort to make changes and additions.
However, it might still be a good idea to take periodic snapshots of a
separate semi-officially designated primary Perl 6 Wiki and stash it in
the source/doc tree (or maybe in a CPAN module Perl6::DOC::Wiki) so that it
would be available for offline help systems / searching.
I'm not really set on any option as long as it works and makes sense
to everyone, including those outside this list. I probably missed it,
but could you give the stated purpose for the wiki again, as I think a
reminder (for me at least) would help.
Several people thought it would be a good idea to have a common place that
made it *easy* to collect and organize useful information about perl6--stuff
that is beyond the scope of standard documentation. There is a lot of
interesting and useful perl6 information that is widely dispersed in talks,
documents, articles, and so on Likewise some of it current, some of it
obsolete, and much in between. Having a central collection that is easy to
browse and that is subject to substantial ongoing indirect review could be
very valuable. Think of the Perl 6 wiki as a vastly expanded FAQ that
supplemented many of the links with semi-consolidated content. Or think of
it as a semi-free-form meta-CPAN for interesting documentation. Or think
of it as a perl6 community gathering point and mega-billboard. Some examples
of suggested content: What are the main benefits of major perl6 features?
Why were various features done one way and not another? How are they
intended to be used? What are the benefits of perl6 relative to other
languages? What are the counter-arguments to various anti-perl6 FUD?
On 24/05/06, Michael Mathews [EMAIL PROTECTED] wrote:
For example
there is nothing stopping anyone (including members of this list) from
creating and populating pages on www.wikipedia.org about Perl6 and
this user group. Then those pages would be available to the wikipedia
search engine. --- Insert any other popular wiki there.
I'd thought of that, but there's always the background issue of moderation
and control. (We definitely want the Perl 6 Wikipedia page to link to our
Perl 6 Wiki, of course.) I don't think Wikipedia is (at present) a suitable
forum for semi-controversial topics. Language advocacy / competitive
marketing is a highly contentious and emotional religious issue for many
people, and we certainly want perl6 people to feel free to indulge in
(reasonably civil) unbridled advocacy of all things perl6.
And of course with the ominipresence of google, finding and searching
is always becoming less of a problem.
In my experience, finding and searching has become more of a problem--in
particular: (1) with too many irrelevant matches, and (2) with too many
matches that turn up obsolete info. That's precisely one of the reasons I
started prodding #perl6 about a newsgroup for perl6 users. Being able to
limit your searches to group archives of what you are specifically
interested in often makes search results much more useful. Precisely one of
the reasons that a Perl 6 Wiki could be very cool is that the content is
more likely to be up to date, and it could thus serve as a good point of
departure for many sorts of perl6 related searches.
What would be annoying though is to invest work in a perl 6 wiki
that is only one of many perl 6 wikis and with no coordination of
efforts between them.
That would also be annoying for a great many users that invested *no* work
as well. There are {browsing,
Re: Perl 6 Wiki -- 2 more possibilities, further discussion.
The (oh so very cool) idea of implementing the perl 6 wiki IN perl 6 (eventually) is a powerful argument. I also concede that control issues mean we don't want the official wiki to be on wikipedia. Kwiki is already a perl-based wiki, but I have no experience using it. We don't have to put perl 6 under the pugs subdomain, that was just an example. --michael On 25/05/06, Conrad Schneiker [EMAIL PROTECTED] wrote: (Responding to 3 notes on 2 mail lists here; Changed subject line.) Juerd wrote: Feather, the semi-public, semi-private, Perl 6 development server, is available to host a Perl 6 wiki. The hostname www.perl6.nl is deliberately kept available for something like that. Does that mean you are willing to be the one to set up a Perl 6 Wiki and administer it? (Preferably using perl5 wiki software, so that the Perl 6 Wiki could be available as soon as possible?) If so, how much more encouragement do you need to proceed? From: Michael Mathews [mailto:[EMAIL PROTECTED] As a competing suggestion, how about... http://pugs.kwiki.org/?perl6 Very interesting. But did you look at it? :-) I found this on the home page link target: Consider using Subversion instead of this Wiki 20051213Z05:58 audreyt I'd like it [the wiki] to be strictly a scratchpad for lambdacamels. all reusable docs should be in the svn tree (and now Perl6::Doc) This reminds me of my earlier suggestion: Could we use part of Pugs doc tree as alternative to perl6-user-doc wiki? http://www.nntp.perl.org/group/perl.perl6.users/28 The basic idea is this: since the pugs svn tree is mirrored at perl.org, we could have a subdirectory (for example Perl_6_ Wiki) in the docs branch of the source tree that would have a wiki-like hierarchy of html pages (or pod pages for generating html) below it. The downside is that it would take somewhat more effort to make changes and additions. However, it might still be a good idea to take periodic snapshots of a separate semi-officially designated primary Perl 6 Wiki and stash it in the source/doc tree (or maybe in a CPAN module Perl6::DOC::Wiki) so that it would be available for offline help systems / searching. I'm not really set on any option as long as it works and makes sense to everyone, including those outside this list. I probably missed it, but could you give the stated purpose for the wiki again, as I think a reminder (for me at least) would help. Several people thought it would be a good idea to have a common place that made it *easy* to collect and organize useful information about perl6--stuff that is beyond the scope of standard documentation. There is a lot of interesting and useful perl6 information that is widely dispersed in talks, documents, articles, and so on Likewise some of it current, some of it obsolete, and much in between. Having a central collection that is easy to browse and that is subject to substantial ongoing indirect review could be very valuable. Think of the Perl 6 wiki as a vastly expanded FAQ that supplemented many of the links with semi-consolidated content. Or think of it as a semi-free-form meta-CPAN for interesting documentation. Or think of it as a perl6 community gathering point and mega-billboard. Some examples of suggested content: What are the main benefits of major perl6 features? Why were various features done one way and not another? How are they intended to be used? What are the benefits of perl6 relative to other languages? What are the counter-arguments to various anti-perl6 FUD? On 24/05/06, Michael Mathews [EMAIL PROTECTED] wrote: For example there is nothing stopping anyone (including members of this list) from creating and populating pages on www.wikipedia.org about Perl6 and this user group. Then those pages would be available to the wikipedia search engine. --- Insert any other popular wiki there. I'd thought of that, but there's always the background issue of moderation and control. (We definitely want the Perl 6 Wikipedia page to link to our Perl 6 Wiki, of course.) I don't think Wikipedia is (at present) a suitable forum for semi-controversial topics. Language advocacy / competitive marketing is a highly contentious and emotional religious issue for many people, and we certainly want perl6 people to feel free to indulge in (reasonably civil) unbridled advocacy of all things perl6. And of course with the ominipresence of google, finding and searching is always becoming less of a problem. In my experience, finding and searching has become more of a problem--in particular: (1) with too many irrelevant matches, and (2) with too many matches that turn up obsolete info. That's precisely one of the reasons I started prodding #perl6 about a newsgroup for perl6 users. Being able to limit your searches to group archives of what you are specifically interested in often makes search results much more useful. Precisely one of the reasons that a Perl 6 Wiki could be very cool is that the
Re: [perl #39056] [BUG] vtable override doesn't work in sub-subclasses
Am Mittwoch, 3. Mai 2006 00:30 schrieb Patrick R.Michaud (via RT): Vtable overrides don't appear to work in a once-removed subclass (i.e., a subclass of a subclass). It's easiest to explain with code: Fixed now in r12797. Thanks for the test. leo
Re: Perl 6 Wiki -- 2 more possibilities, further discussion.
Please, for proper threading, don't reply to multiple messages at once. Conrad Schneiker skribis 2006-05-25 1:46 (-0700): Juerd wrote: Feather, the semi-public, semi-private, Perl 6 development server, is available to host a Perl 6 wiki. The hostname www.perl6.nl is deliberately kept available for something like that. Does that mean you are willing to be the one to set up a Perl 6 Wiki and administer it? (Preferably using perl5 wiki software, so that the Perl 6 Wiki could be available as soon as possible?) If so, how much more encouragement do you need to proceed? Willing, certainly. Lacking tuits, that too. I could set up wiki software in a few minutes, but then, so could anyone else. Personally, I think this shouldn't be rushed: there are lots of wikis, and typically they're incompatible in terms of syntax and storage. Also, I'd really love a Perl 6 wiki written in Perl 6 itself. Revision control can be outsourced to svn, leaving practically only a small bit of HTTP and wikitext parsing. However, this is still too much work for me to handle at this moment. The concept of feather is that I provide hardware, and system administration, and that others can then use that. Feather is very actively used, and it'd be nonsense to assume that everything on it is, or should be, done by me. I actively avoid getting involved too much, because I know that I won't be able to handle things as they expand. Feather was donated exactly because I wanted to do something for Perl 6 volunteers, without needing to spend much time, because I don't have that much time to spend on computing, because of personal circumstances. As a competing suggestion, how about... http://pugs.kwiki.org/?perl6 Very interesting. But did you look at it? :-) I found this on the home page link target: I know, and have contributed to, the Pugs wiki. If I may note: I don't like kwiki syntax, and much prefer a mediawiki-like syntax. I'd thought of that, but there's always the background issue of moderation and control. (We definitely want the Perl 6 Wikipedia page to link to our Perl 6 Wiki, of course.) I don't think Wikipedia is (at present) a suitable forum for semi-controversial topics. Language advocacy / competitive marketing is a highly contentious and emotional religious issue for many people, and we certainly want perl6 people to feel free to indulge in (reasonably civil) unbridled advocacy of all things perl6. Agreed. Feather has the powerful future marketing advantage that it can also be used to develop and then host a showcase Perl 6 implementation of the Perl 6 Wiki. However, I think that we should initially *begin* with a solid and proven Perl 5 wiki implementation that we can use *immediately*. If we could do this, then this would be my first preference. Beginning with a Perl 5 wiki, with lots of features, and migrating to a Perl 6 wiki later, means you have to support all of the 5-wiki's features for compatibility. That may not be a great plan, as a huge stack of functional requirements makes creative programming less interesting, and it may then never happen. If nobody is able to spend a day on a simple Perl 6 wiki today, why would they be able to spend *several* days on a backwards compatible wiki later? Juerd -- http://convolution.nl/maak_juerd_blij.html http://convolution.nl/make_juerd_happy.html http://convolution.nl/gajigu_juerd_n.html
perldoc or pod parser in Perl6
sligthly related to the Perl6 wiki issue, is there a perldoc command or a podparser implemented in Perl6 already ? Gabor
Re[2]: perl 6 hosting?
GS The hard part is to make sure they won't write code to exploit other sites or GS create hug load on your machine... Any idea of how to avoid endless loops? :-) Restricting execution time? -- ___ Andrew, [EMAIL PROTECTED] ___
Re: Logic Programming for Perl6 (Was Re: 3 Good Reasons... (typo alert!))
This topic may be better suited to perl6-language, unless you consider its denizens to already be self-selected against logic programming. :) Larry
Instructions to build parrot using mingw
All: It has been 1.5 years since I have built parrot and a lot has changed. Today I decided to dust off some old projects but I am having trouble getting it to build. Previously, I used Cygwin. I have mingw, msys, and ActiveState Perl Unfortunately, I do not have permission to create files in C:\Windows\system32 so the conf.ini files that go there in support of mingw and msys are missing. That may be part of my problem. Here is where I am at: C:\parrotperl Configure.pl C:\parrotmingw32-make Compiling with: xx.c gcc -I.\include -DWIN32 -g -Wall -Wstrict-prototypes -Wmissing-prototypes -Winline -Wshadow -Wpointer-arith -W cast-qual -Wwrite-strings -Waggregate-return -Winline -W -Wno-unused -Wsign-compare -Wformat-nonliteral -Wform at-security -Wpacked -Wdisabled-optimization -mno-accumulate-outgoing-args -Wno-shadow -falign-functions=16 -D HAS_JIT -DI386 -DHAVE_COMPUTED_GOTO -I. -o xx.o -c xx.c /usr/bin/sh: C:perlbinperl.exe: command not found mingw32-make: *** [src\ops\core_ops.o] Error 127 Notice C:perlbinperl.exe The path delimiter is apparently getting interpreted as a shell escape. I have tried playing around with config/init/hints/mswin32.pm to no avail. Anyone know what my problems is or is willing to work with me on this would be most appreciated. Cheers, Joshua Gatcomb a.k.a. Limbic~Region
[svn:perl6-synopsis] r9307 - doc/trunk/design/syn
Author: larry
Date: Thu May 25 11:21:16 2006
New Revision: 9307
Modified:
doc/trunk/design/syn/S06.pod
Log:
Clarifying the distinction between the of and where return types.
Modified: doc/trunk/design/syn/S06.pod
==
--- doc/trunk/design/syn/S06.pod(original)
+++ doc/trunk/design/syn/S06.podThu May 25 11:21:16 2006
@@ -13,9 +13,9 @@
Maintainer: Larry Wall [EMAIL PROTECTED]
Date: 21 Mar 2003
- Last Modified: 14 May 2006
+ Last Modified: 24 May 2006
Number: 6
- Version: 35
+ Version: 36
This document summarizes Apocalypse 6, which covers subroutines and the
@@ -288,7 +288,7 @@
including Unicode characters. For example:
sub infix:(c) ($text, $owner) { return $text but Copyright($owner) }
-method prefix:± (Num $x) returns Num { return +$x | -$x }
+method prefix:± (Num $x -- Num) { return +$x | -$x }
multi sub postfix:! (Int $n) { $n 2 ?? 1 !! $n*($n-1)! }
macro circumfix:«!-- --» ($text) is parsed / .*? / { }
@@ -1238,7 +1238,7 @@
Note that unlike a sub declaration, a regex-embedded signature has no
associated returns syntactic slot, so you have to use C --
-within the signature to specify the type of the signature, or match as
+within the signature to specify the Cof type of the signature, or match as
an arglist:
:(Num, Num -- Coord)
@@ -1395,15 +1395,21 @@
Explicit types are optional. Perl variables have two associated types:
their value type and their implementation type. (More generally, any
container has an implementation type, including subroutines and modules.)
+The value type is stored as its Cof property, while the implementation
+type of the container is just the object type of the container itself.
The value type specifies what kinds of values may be stored in the
-variable. A value type is given as a prefix or with the Creturns or
-Cof keywords:
+variable. A value type is given as a prefix or with the Cof keyword:
my Dog $spot;
-my $spot returns Dog;
my $spot of Dog;
+In either case this sets the Cof property of the container to CDog.
+Subroutines have a variant of the Cof property, Creturns, that
+sets the Creturns property instead. The Creturns property specifies
+a constraint to be checked upon calling Creturn that, unlike the Cof
+property, is not advertized as the type of the routine:
+
our Animal sub get_pet() {...}
sub get_pet() returns Animal {...}
sub get_pet() of Animal {...}
@@ -1431,6 +1437,13 @@
run-time Ctie statement unless the variable is explicitly declared
with an implementation type that does the CTieable role.
+However, package variables are always considered CTieable by default.
+As a consequence, all named packages are also CTieable by default.
+Classes and modules may be viewed as differently tied packages.
+Looking at it from the other direction, classes and modules that
+wish to be bound to a global package name must be able to do the
+CPackage role.
+
=head2 Hierarchical types
A non-scalar type may be qualified, in order to specify what type of
@@ -1449,19 +1462,16 @@
actually means:
-my Hash[returns = Array[returns = Recipe]] %book;
+my Hash[of = Array[of = Recipe]] %book;
Because the actual variable can be hard to find when complex types are
specified, there is a postfix form as well:
my Hash of Array of Recipe %book; # HoHoAoRecipe
my %book of Hash of Array of Recipe;# same thing
-my %book returns Hash of Array of Recipe; # same thing
-The Creturns form is more commonly seen in subroutines:
+The Creturns form may be used in subroutines:
-my Hash of Array of Recipe sub get_book ($key) {...}
-my sub get_book ($key) of Hash of Array of Recipe {...}
my sub get_book ($key) returns Hash of Array of Recipe {...}
Alternately, the return type may be specified within the signature:
@@ -1469,8 +1479,14 @@
my sub get_book ($key -- Hash of Array of Recipe) {...}
There is a slight difference, insofar as the type inferencer will
-ignore a Creturns but pay attention to C -- or prefix type
declarations.
-Only the inside of the subroutine pays attention to Creturns.
+ignore a Creturns but pay attention to C -- or prefix type
+declarations, also known as the Cof type. Only the inside of the
+subroutine pays attention to Creturns.
+
+You may also specify the Cof type as the Cof trait:
+
+my Hash of Array of Recipe sub get_book ($key) {...}
+my sub get_book ($key) of Hash of Array of Recipe {...}
=head2 Polymorphic types
@@ -1524,42 +1540,53 @@
=head2 Return types
On a scoped subroutine, a return type can be specified before or
-after the name:
-
-our Egg sub lay {...}
-our sub lay returns Egg {...}
-
-my Rabbit sub hat {...}
-my sub hat returns Rabbit {...}
+after the name. We call all return types return types, but distinguish
+two kinds of return type, the
Re: Logic Programming for Perl6 (Was Re: 3 Good Reasons... (typo alert!))
- Original Message
From: David Romano [EMAIL PROTECTED]
duplicate results and this is almost always wrong. (See
http://use.perl.org/~Ovid/journal/28378
for an SQL example of this problem).
I re-read your journal entry and comments (I had read it back when you
first had posted it), and I'm curious about what obstacles that you
think need to be overcome for Perl6 to support logic programming.
If anyone wants to know what the heck this is about, you can read
http://search.cpan.org/dist/AI-Prolog/lib/AI/Prolog/Article.pod
That's an article I originally had published in The Perl Review
(http://www.theperlreview.com/) and it explains the basics of logic programming
and how to do it in Perl5. It also explains the append/3 predicate, something
I mention below.
The first hurdle would be the syntax. The programmer just looking at the code
would need to know when one section of code represents a snippet of logic
programming. Is the following a function call or a Prolog fact?
loves( 'foo', 'bar' );
How would one assert facts and rules in Perl6? How would one know that a
variable is a logic variable and not a normal one? Assignment to a logic
variable which is still subject to rebinding could break code. On the other
hand, using normal variables for logic variables could let us use objects for
them and I think this might get us contraint programming (long story).
There's also the question of non-logical behavior in logic programming. What
happens if you try to use math in Perl6 logic programming? Generally speaking,
math is non-logical in the sense that it's used in Prolog (see the
aforementioned article). Opening and reading from a file is also non-logical
(you can't backtrack over it). How are those issues to be handled?
My biggest concern, though, is a rule like the following:
customer_cities(City) :-
700 = credit_rating(Customer),
customer(Customer, City).
That's logically equivalent to the SQL I posted in a previous email and, like
that SQL, will very likely return duplicates. Prolog students are constantly
faced wtih the how do I get rid of duplicates? problem. This results in
inefficient queries and a lot of time spent culling the duplicate answers when
the person just wants to know the list of cities which meets their requirements.
Perl6 grammars may be able to assist with this, but grammars (as far as I can
tell) are still based around strings and not data structures. Admittedly,
Prolog is essentially a fancy string rewriting system, but it's not clear how
the grammars would be applied to this problem.
For anyone familiar with logic programming and the append/3 predicate, here's
one way of representing it in Perl5:
use re 'eval';
my $string = abc;
my $length = length $string;
my $regex = qr/(\G[$string]{0,$length}(?{print # [$][$'][$string]\n}))/ x
2;
$string =~ $regex;
Can you say yuck? However, that only represents a limited subset of
append/3's functionality and trying to generalize it would be a very difficult
task. One approach might be to write a wrapper around
http://www.perlmonks.org/?node_id=318350. That's an approach I found to
leverage Perl5's regex engine for logic programming, but I discovered that
Perl5's regexen aren't re-entrant, killing that project. Perl6 rules might be
perfect for this.
In short, there are lots of questions which would need to be answered to get
logic programming done correctly in Perl6. I'm quite happy that @Larry decided
not to answer those questions since things would have been delayed. We can
hack in logic programming later.
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/
Fw: Logic Programming for Perl6 (Was Re: 3 Good Reasons... (typo alert!))
Larry pointed out that this topic is better suited for perl6-language instead
of perl6-users, so I'm forwarding this along. Feel free to exercise your
delete key.
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/
- Forwarded Message
From: Ovid [EMAIL PROTECTED]
To: perl6-users@perl.org
Sent: Thursday, May 25, 2006 11:40:54 AM
Subject: Re: Logic Programming for Perl6 (Was Re: 3 Good Reasons... (typo
alert!))
- Original Message
From: David Romano [EMAIL PROTECTED]
duplicate results and this is almost always wrong. (See
http://use.perl.org/~Ovid/journal/28378
for an SQL example of this problem).
I re-read your journal entry and comments (I had read it back when you
first had posted it), and I'm curious about what obstacles that you
think need to be overcome for Perl6 to support logic programming.
If anyone wants to know what the heck this is about, you can read
http://search.cpan.org/dist/AI-Prolog/lib/AI/Prolog/Article.pod
That's an article I originally had published in The Perl Review
(http://www.theperlreview.com/) and it explains the basics of logic programming
and how to do it in Perl5. It also explains the append/3 predicate, something
I mention below.
The first hurdle would be the syntax. The programmer just looking at the code
would need to know when one section of code represents a snippet of logic
programming. Is the following a function call or a Prolog fact?
loves( 'foo', 'bar' );
How would one assert facts and rules in Perl6? How would one know that a
variable is a logic variable and not a normal one? Assignment to a logic
variable which is still subject to rebinding could break code. On the other
hand, using normal variables for logic variables could let us use objects for
them and I think this might get us contraint programming (long story).
There's also the question of non-logical behavior in logic programming. What
happens if you try to use math in Perl6 logic programming? Generally speaking,
math is non-logical in the sense that it's used in Prolog (see the
aforementioned article). Opening and reading from a file is also non-logical
(you can't backtrack over it). How are those issues to be handled?
My biggest concern, though, is a rule like the following:
customer_cities(City) :-
700 = credit_rating(Customer),
customer(Customer, City).
That's logically equivalent to the SQL I posted in a previous email and, like
that SQL, will very likely return duplicates. Prolog students are constantly
faced wtih the how do I get rid of duplicates? problem. This results in
inefficient queries and a lot of time spent culling the duplicate answers when
the person just wants to know the list of cities which meets their requirements.
Perl6 grammars may be able to assist with this, but grammars (as far as I can
tell) are still based around strings and not data structures. Admittedly,
Prolog is essentially a fancy string rewriting system, but it's not clear how
the grammars would be applied to this problem.
For anyone familiar with logic programming and the append/3 predicate, here's
one way of representing it in Perl5:
use re 'eval';
my $string = abc;
my $length = length $string;
my $regex = qr/(\G[$string]{0,$length}(?{print # [$][$'][$string]\n}))/ x
2;
$string =~ $regex;
Can you say yuck? However, that only represents a limited subset of
append/3's functionality and trying to generalize it would be a very difficult
task. One approach might be to write a wrapper around
http://www.perlmonks.org/?node_id=318350. That's an approach I found to
leverage Perl5's regex engine for logic programming, but I discovered that
Perl5's regexen aren't re-entrant, killing that project. Perl6 rules might be
perfect for this.
In short, there are lots of questions which would need to be answered to get
logic programming done correctly in Perl6. I'm quite happy that @Larry decided
not to answer those questions since things would have been delayed. We can
hack in logic programming later.
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/
Re: CPANTS is not a game.
- Original Message From: David Golden [EMAIL PROTECTED] formatted. E.g. I believe this is sufficient to get the Kwalitee point: # t/pod_coverage.t __END__ use Test::Pod::Coverage; What? You think that's bad? Here are three lines from Acme::Code::Police: $trick_that_naughty_cpants_thingy_into_thinking_I_use_strict = 'Ha, ha!'; use strict; Ha, ha!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/
Re: 3 Good Reasons...
Michael Mathews [EMAIL PROTECTED] writes: So my question to the list is, in simple terms even an IT manager could grasp, explain what problems Perl 5 has that Perl 6 fixes, such that they would want to undergo the pain of ever switching. From a Perl point of view: there should be no pain. At least that's a stated goal. From a manager point of view: it's as use(ful|less) as ever to decide for a language independently of the problem to solve. If Perl5 does the job, stick with it. If Perl6 helps you somewhere, use it. If Visual Basic solves your problem because it's already built into the problem, just use it. Perl5 is already gluey enough to not force you into a decicion for *the only one* technology. Perl6 shouldn't change that. Steffen -- Steffen Schwigon [EMAIL PROTECTED] Dresden Perl Mongers http://dresden-pm.org/
Re: CPANTS is not a game.
Le mardi 23 mai 2006 à 21:56, Thomas Klausner écrivait: And no, I won't take the fun out of CPANTS. Then why did you filter out the Acme modules from the prereq lists? Mmm? For example, see http://cpants.perl.org/dist/Bot-MetaSyntactic and http://cpants.perl.org/dist/Acme-MetaSyntactic-RefactorCode Both list Acme::MetaSyntactic as a prerequisite in Makefile.PL, but it doesn't appear in the Listed Prerequisites nor in the Modules/pragmas/etc use'd by Acme-MetaSyntactic-RefactorCode lists (and therefore doesn't get its well earned is_prereq point). Another side effect is that CPANTS gives false information. -- Philippe BooK Bruhat Out of the worst can often come the best. (Moral from Groo The Wanderer #57 (Epic))
PBC meta info
While reading pdd23 and thinking of implementation strategies for
.begin_eh / .end_eh the following ideas jumped onto my branes:
- .begin_eh / .end_eh is by far not the only metainfo we want / need in
PBC files
- we already have debug info (line numbers / file info = PC relation)
- we need more like HLL debug info / src code info
- there's also perl6 =pod stuff coming somewhen
- and last but not least some P6 COMPILING stuff comes to my mind
(whatever that does)
- we also want to convert current PackFile structures to some PMCs,
which are more accessible to runtime
The needed meta info can of course all be hardcoded somehow into imcc
files but that's all not reusable and general. Therefore I was thinking
about utilizing existing stuff namely PIR to accomplish the same task.
Here's a first draft of the exception handler range setup code:
.begin_eh LABEL =
.meta {
$I0 = exists $META['EH_range']
if $I0 goto init_ok
$P0 = new .ResizablePMCArray
$META['EH_range'] = $P0
last_eh_range = new .ResizablePMCArray # decl / '_parrot'
global access omitted
init_ok:
$P0 = $META['EH_range']
$P1 = new .FixedIntegerArray
$P1 = 3
$P1[0] = $PC
$P1[1] = $LABEL
push $P0, $P1
push last_eh_range, $P1
}
.end_eh =
.meta {
$P1 = pop last_eh_range
$P1[2] = $PC
}
So the idea is:
- we enable running code during compilation and even per line
(triggered by meta directives)
(:immediate is only per subroutine and a bit different)
- above snippets are actually subroutines, called with needed/used
arguments like the $META hash, $PC (program counter), line number,
whatever
- these subs are autoloaded from some compiler library
- the code isn't ment to run arbitrary actions, but just to create
needed meta information ...
- which is basically one frozen PMC aggregate: the %META hash, with
named sections, which are some other structures like the array of
exception handler ranges
- this metainfo is then of course available at runtime via e.g. the
interpinfo opcode
There are of course some implementation obstacles (we want to create
constant/persistent PMCs, access the constant table...) but it might be
worth the effort to attack the general solution.
What do you think?
leo
Fwd: 3 Good Reasons...
Hi Steffen, I'm glad you made that point. If I understand your statement, it's a common gain cited by Perl 6 (actually Parrot) advocates: you can mix languages. But a point I was trying to make was that while this is fun for us developers, managers hate it, with very good reason. Having one crucial part of a system written in, say Python, when the other 98%is in Perl, is actually considered a Bad Thing. It means having to have experts in two languages around at all times should anything go wrong. Obviously this is more expensive and more effort than having to maintain just one language. I'm not trying to pick a fight with Parrot here, in fact I think the best way to put it is more along the lines that Perl 5/6, on Parrot, will compile down to a *language independent* format. At least I think that's so. Someone correct me here, especially as that's what I think Steffen was saying. So does that mean I can write a module in Perl 6, deliver it to Mr. Customer as byte-code. Then Mr. Customer can decompile(?) it into Python (or JavaScript, or C, etc), edit it, and then compile it back into working byte-code again? 'Cause if THAT were true then it would be revolutionary and businesses would be fighting to get their hands on it (once it was stable and proven). Much more inviting than saying Parrot will allow lots of different languages to start sprouting up in unexpected areas of the company's code base. --michael On 25/05/06, Steffen Schwigon [EMAIL PROTECTED] wrote: Michael Mathews [EMAIL PROTECTED] writes: So my question to the list is, in simple terms even an IT manager could grasp, explain what problems Perl 5 has that Perl 6 fixes, such that they would want to undergo the pain of ever switching. From a Perl point of view: there should be no pain. At least that's a stated goal. From a manager point of view: it's as use(ful|less) as ever to decide for a language independently of the problem to solve. If Perl5 does the job, stick with it. If Perl6 helps you somewhere, use it. If Visual Basic solves your problem because it's already built into the problem, just use it. Perl5 is already gluey enough to not force you into a decicion for *the only one* technology. Perl6 shouldn't change that. Steffen -- Steffen Schwigon [EMAIL PROTECTED] Dresden Perl Mongers http://dresden-pm.org/
Re: Instructions to build parrot using mingw
Hello, do not use msys. Try mingw32-make from cmd.exe. http://wiki.kn.vutbr.cz/mj/index.cgi?Build%20Parrot%20with%20MinGW can probably help too. Michal Jurosz Joshua Gatcomb wrote: All: It has been 1.5 years since I have built parrot and a lot has changed. Today I decided to dust off some old projects but I am having trouble getting it to build. Previously, I used Cygwin. I have mingw, msys, and ActiveState Perl Unfortunately, I do not have permission to create files in C:\Windows\system32 so the conf.ini files that go there in support of mingw and msys are missing. That may be part of my problem. Here is where I am at: C:\parrotperl Configure.pl C:\parrotmingw32-make Compiling with: xx.c gcc -I.\include -DWIN32 -g -Wall -Wstrict-prototypes -Wmissing-prototypes -Winline -Wshadow -Wpointer-arith -W cast-qual -Wwrite-strings -Waggregate-return -Winline -W -Wno-unused -Wsign-compare -Wformat-nonliteral -Wform at-security -Wpacked -Wdisabled-optimization -mno-accumulate-outgoing-args -Wno-shadow -falign-functions=16 -D HAS_JIT -DI386 -DHAVE_COMPUTED_GOTO -I. -o xx.o -c xx.c /usr/bin/sh: C:perlbinperl.exe: command not found mingw32-make: *** [src\ops\core_ops.o] Error 127 Notice C:perlbinperl.exe The path delimiter is apparently getting interpreted as a shell escape. I have tried playing around with config/init/hints/mswin32.pm to no avail. Anyone know what my problems is or is willing to work with me on this would be most appreciated. Cheers, Joshua Gatcomb a.k.a. Limbic~Region
Re: Fw: Logic Programming for Perl6 (Was Re: 3 Good Reasons... (typo alert!))
Hmm... How about this: Treat each knowledge base as an object, with at least two methods: .fact() takes the argument list and constructs a prolog-like fact or rule out of it, which then gets added to the knowledge base. .query() takes the argument list, constructs a prolog-like query out of it, and returns a lazy list of the results. There would be a default knowledge base, meaning that you wouldn't have to explicitly state which knowledge base you're using every time you declare a fact or make a query. -- Jonathan Lang
Re: [svn:perl6-synopsis] r9307 - doc/trunk/design/syn
[EMAIL PROTECTED] wrote: +In either case this sets the Cof property of the container to CDog. +Subroutines have a variant of the Cof property, Creturns, that +sets the Creturns property instead. The Creturns property specifies +a constraint to be checked upon calling Creturn that, unlike the Cof +property, is not advertized as the type of the routine: It doesn't have to be run-time; it could also merely alter the signature of the (implied or explicit) return() function within that sub. Sam.
Re: Logic Programming for Perl6 (Was Re: 3 Good Reasons... (typo alert!))
* Ovid [EMAIL PROTECTED] [2006-05-25 20:45]: The first hurdle would be the syntax. The programmer just looking at the code would need to know when one section of code represents a snippet of logic programming. Is the following a function call or a Prolog fact? loves( 'foo', 'bar' ); How would one assert facts and rules in Perl6? How would one know that a variable is a logic variable and not a normal one? Don’t forget that in Perl 6, the parser grammar is wide open for modification. That is not an opportunity to be used lightly, but I believe logic programming is a sufficiently “big” and distinct extension that it justifies dedicated syntax. Regards, -- Aristotle Pagaltzis // http://plasmasturm.org/
