From jacoby at purdue.edu  Mon Mar  1 08:26:36 2010
From: jacoby at purdue.edu (David Jacoby)
Date: Mon, 01 Mar 2010 11:26:36 -0500
Subject: [Purdue-pm] Copying Hashrefs - A Better Way?
Message-ID: <4B8BEABC.4090700@purdue.edu>

I want to copy a hashref. Well, I want to copy the hash reffed, not the 
pointer. This is not it.

     my $href_1 ;
     $href->{x} = 8 ;
     my $href_2 = $href_1 ;

You just get a pointer to the old hash, not a new hash. I want to copy 
the anonymous hash that $href_1 is referring to.

     my $href_1 ;
     my $href_2 ;
     $href->{x} = 8 ;

     %$href_2 =  map { $_ } %$href_1 ;

Yes, this works. But is there a better way?

-- 
Dave Jacoby                         Address: WSLR S049
Genomics Core Programmer            Mail:    jacoby at purdue.edu
Purdue University                   Phone:   765.49.67368

From westerman at purdue.edu  Mon Mar  1 09:12:15 2010
From: westerman at purdue.edu (Rick Westerman)
Date: Mon, 01 Mar 2010 12:12:15 -0500
Subject: [Purdue-pm] Copying Hashrefs - A Better Way?
In-Reply-To: <4B8BEABC.4090700@purdue.edu>
References: <4B8BEABC.4090700@purdue.edu>
Message-ID: <4B8BF56F.1070005@purdue.edu>

David Jacoby wrote:
> I want to copy a hashref. Well, I want to copy the hash reffed, not 
> the pointer. This is not it.
>
>     my $href_1 ;
>     $href->{x} = 8 ;
>     my $href_2 = $href_1 ;
>
> You just get a pointer to the old hash, not a new hash. I want to copy 
> the anonymous hash that $href_1 is referring to.
>
>     my $href_1 ;
>     my $href_2 ;
>     $href->{x} = 8 ;
>
>     %$href_2 =  map { $_ } %$href_1 ;
>
> Yes, this works. But is there a better way?
>
I'd say no.   Although you can drop the 'map' part.  But I believe the 
normal hash copy uses 'map' internally so leaving it in does not really 
matter. 

Basically you are creating a new hash in memory.    In long form -- to 
emphasize the point -- what you are doing is (where %h1 and %h2 are 
actual memory-using hashes) is basically:

(created elsewhere):  %h1

my $href_1 = \%h1;

my %h2;
my $href_2 = \%h2 ;

If you were just working with hashes instead of hash references you 
would do a:

%h2 = %h1 ;

With references the syntax is not any different

%h2 = %$href_1 ;

or

%$href_2 = %$href_1 ;


Of course one then should ask, why do I need a complete copy of a hash?  
There may be good reason.  Or perhaps better is to use 'grep' (akin to 
'map') to filter the data from the old hash into the new hash.


-- 
Rick Westerman westerman at purdue.edu Bioinformatics specialist at the 
Genomics Facility. Phone: (765) 494-0505 FAX: (765) 496-7255 Department 
of Horticulture and Landscape Architecture 625 Agriculture Mall Drive 
West Lafayette, IN 47907-2010 Physically located in room S049, WSLR 
building

From mark at purdue.edu  Tue Mar  9 04:38:52 2010
From: mark at purdue.edu (Mark Senn)
Date: Tue, 09 Mar 2010 07:38:52 -0500
Subject: [Purdue-pm] FYI: Google Summer of Code
Message-ID: <6732.1268138332@pier.ecn.purdue.edu>

>From: Eric Wilhelm <scratchcomputing at gmail.com>
>To: PM Groups <pm_groups at pm.org>
>Date: Mon, 8 Mar 2010 22:58:22 -0800
>User-Agent: KMail/1.9.9
>Subject: [pm_groups] Fwd: Calling All Google Summer of Code Mentors
>Sender: pm_groups-bounces+mark=purdue.edu at pm.org
>X-PerlMx-Virus-Scanned: Yes
>X-ECN-MailServer-VirusScanned: by amavisd-new
>X-ECN-MailServer-Origination: mailhub248.itcs.purdue.edu [128.210.5.248]
>X-ECN-MailServer-SpamScanAdvice: DoNotScan
>
>Hi all,
>
>Please forward this to your local groups and help spread the word this 
>month about getting involved in Google Summer of Code.
>
>  http://www.perlfoundation.org/perl5/index.cgi?gsoc_perlmongers
>
>Thanks,
>Eric
>----------  Forwarded Message:  ----------
>
>Subject: Calling All Google Summer of Code Mentors
>Date: Monday 08 March 2010
>From: Jonathan Leto <jaleto at gmail.com>
>To: Portland Perl Mongers <pdx-pm-list at pm.org>
>
>Howdy,
>
>I am working on the application for The Perl Foundation and Parrot
>Foundation to participate in Google Summer of Code 2010 [0]. GSoC is a
>program where Google funds eligible students to hack on open source
>projects for a summer. It is a great opportunity for the students and
>the communities that mentor them. You also may be interested in this
>summary of our involvement last year [1]. Our application will be
>submitted by the end of this week.
>
>Please join us in getting prepared for this year. There is a page for
>possible mentors to volunteer [2]* as well as a page for project ideas
>[3]. If you would like to help with the wiki, our main GSoC page [4]
>is the best place to start. You are also invited to join our mailing
>list [5] and come ask question in #soc-help on irc.perl.org .
>
>Thanks!
>
>Duke
>
>[0] http://socghop.appspot.com/
>[1] 
>http://google-opensource.blogspot.com/2009/10/perls-of-wisdom-perl-foundation-parrots.html
>[2] http://www.perlfoundation.org/perl5/index.cgi?gsoc_mentors
>[3] http://www.perlfoundation.org/perl5/index.cgi?gsoc_2010_projects
>[4] http://www.perlfoundation.org/perl5/index.cgi?gsoc
>[5] http://groups.google.com/group/tpf-gsoc
>
>* If you listed yourself as a mentor last year and you are not
>interested this year, please remove yourself from the page.
>
>--
>Jonathan "Duke" Leto
>jonathan at leto.net
>http://leto.net
>--
>Request pm.org Technical Support via support at pm.org
>
>pm_groups mailing list
>pm_groups at pm.org
>http://mail.pm.org/mailman/listinfo/pm_groups

From westerman at purdue.edu  Wed Mar 10 08:43:26 2010
From: westerman at purdue.edu (Rick Westerman)
Date: Wed, 10 Mar 2010 11:43:26 -0500
Subject: [Purdue-pm] Reminder, meeting this Tuesday, March 16th
Message-ID: <4B97CC2E.7090207@purdue.edu>

At the moment only Mark is scheduled to present.  His offerings sound 
interesting.  As usual if someone else wishes to present (even at the 
last moment) then please do so.

WSLR 116, Noon to 1 with social time starting around 11:30.  Tuesday 
March 16th

-- 
Rick Westerman westerman at purdue.edu Bioinformatics specialist at the 
Genomics Facility. Phone: (765) 494-0505 FAX: (765) 496-7255 Department 
of Horticulture and Landscape Architecture 625 Agriculture Mall Drive 
West Lafayette, IN 47907-2010 Physically located in room S049, WSLR 
building

From gizmo at purdue.edu  Mon Mar 15 09:54:11 2010
From: gizmo at purdue.edu (Joe Kline)
Date: Mon, 15 Mar 2010 12:54:11 -0400
Subject: [Purdue-pm] Reminder, meeting this Tuesday, March 16th
In-Reply-To: <18584_1268239271_o2AGf9GT028445_4B97CC2E.7090207@purdue.edu>
References: <18584_1268239271_o2AGf9GT028445_4B97CC2E.7090207@purdue.edu>
Message-ID: <4B9E6633.2070608@purdue.edu>

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Rick,

I thought I was going to do a summary of the Effective Perl class I went
to in February (and probably roll in my summary of the sorting methods
in Perl since that was covered in the class)?

joe
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From westerman at purdue.edu  Mon Mar 15 09:59:00 2010
From: westerman at purdue.edu (Rick Westerman)
Date: Mon, 15 Mar 2010 12:59:00 -0400
Subject: [Purdue-pm] Reminder, meeting this Tuesday, March 16th
In-Reply-To: <4B9E6633.2070608@purdue.edu>
References: <18584_1268239271_o2AGf9GT028445_4B97CC2E.7090207@purdue.edu>
	<4B9E6633.2070608@purdue.edu>
Message-ID: <4B9E6754.3080807@purdue.edu>

Joe Kline wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> Rick,
>
> I thought I was going to do a summary of the Effective Perl class I went
> to in February (and probably roll in my summary of the sorting methods
> in Perl since that was covered in the class)?
>
> joe
>   

That would be good.  I'll put you down on the wiki.  See you tomorrow.

-- 
Rick Westerman westerman at purdue.edu Bioinformatics specialist at the 
Genomics Facility. Phone: (765) 494-0505 FAX: (765) 496-7255 Department 
of Horticulture and Landscape Architecture 625 Agriculture Mall Drive 
West Lafayette, IN 47907-2010 Physically located in room S049, WSLR 
building

From gizmo at purdue.edu  Fri Mar 19 04:05:50 2010
From: gizmo at purdue.edu (Joe Kline)
Date: Fri, 19 Mar 2010 07:05:50 -0400
Subject: [Purdue-pm] literate programming
Message-ID: <4BA35A8E.6060906@purdue.edu>

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

A post about literate programming and POD or at least a lament.

http://www.lowlevelmanager.com/2010/03/pod-is-not-literate-programming.html
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From mdw at purdue.edu  Fri Mar 19 06:14:13 2010
From: mdw at purdue.edu (Mark Daniel Ward)
Date: Fri, 19 Mar 2010 09:14:13 -0400
Subject: [Purdue-pm] literate programming
In-Reply-To: <4BA35A8E.6060906@purdue.edu>
References: <4BA35A8E.6060906@purdue.edu>
Message-ID: <4BA378A5.8030802@purdue.edu>

Dear Joe,
     Literate Programming is an awesome idea.  I'm very familiar with 
Knuth's work and his belief in Literate Programming.  Knuth is the main 
guy in my field, and I know him very well (we've met on several 
occasions, and I am one of 4 people in the world to proofread his 
"Selected Papers" books before they are published, at Don's direct request).
     If you guys decide to talk about Literate Programming in one of the 
Perl meetings, I would probably be inspired to come!
Mark



On 3/19/10 7:05 AM, Joe Kline wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> A post about literate programming and POD or at least a lament.
>
> http://www.lowlevelmanager.com/2010/03/pod-is-not-literate-programming.html
> -----BEGIN PGP SIGNATURE-----
> Version: GnuPG v1.4.9 (GNU/Linux)
> Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/
>
> iEYEARECAAYFAkujWo0ACgkQb0mzA2gRTpnfEACfetJgXetEug0Y1o+wJAHagsXg
> DiYAn0YQWzADX1YvQcJoTE4IWnfOQL8l
> =E7U0
> -----END PGP SIGNATURE-----
> _______________________________________________
> Purdue-pm mailing list
> Purdue-pm at pm.org
> http://mail.pm.org/mailman/listinfo/purdue-pm
>
>    

From mark at ecn.purdue.edu  Fri Mar 19 06:26:07 2010
From: mark at ecn.purdue.edu (Mark Senn)
Date: Fri, 19 Mar 2010 09:26:07 -0400
Subject: [Purdue-pm] literate programming
In-Reply-To: <4BA378A5.8030802@purdue.edu>
References: <4BA35A8E.6060906@purdue.edu> <4BA378A5.8030802@purdue.edu>
Message-ID: <6838.1269005167@pier.ecn.purdue.edu>

Mark Daniel Ward <mdw at purdue.edu> wrote at 2010-03-19 09:14:
> Dear Joe,
>     Literate Programming is an awesome idea.  I'm very familiar with
> Knuth's work and his belief in Literate Programming.  Knuth is the
> main guy in my field, and I know him very well (we've met on several
> occasions, and I am one of 4 people in the world to proofread his
> "Selected Papers" books before they are published, at Don's direct
> request).
>     If you guys decide to talk about Literate Programming in one of
> the Perl meetings, I would probably be inspired to come!
> Mark

T gave a talk that included information about TELPS (The Extensible
Literate Programming System) I'm developing.  It is pre-alpha and
experimental.  I'll send another message out Sunday, 2010-03-21,
about it.    -mark

From mdw at purdue.edu  Fri Mar 19 06:29:07 2010
From: mdw at purdue.edu (Mark Daniel Ward)
Date: Fri, 19 Mar 2010 09:29:07 -0400
Subject: [Purdue-pm] literate programming
In-Reply-To: <6838.1269005167@pier.ecn.purdue.edu>
References: <4BA35A8E.6060906@purdue.edu> <4BA378A5.8030802@purdue.edu>
	<6838.1269005167@pier.ecn.purdue.edu>
Message-ID: <4BA37C23.7@purdue.edu>

Dear Mark,
     Great!  Please keep me posted.  Sounds interesting.
Mark


On 3/19/10 9:26 AM, Mark Senn wrote:
> Mark Daniel Ward<mdw at purdue.edu>  wrote at 2010-03-19 09:14:
>    
>> Dear Joe,
>>      Literate Programming is an awesome idea.  I'm very familiar with
>> Knuth's work and his belief in Literate Programming.  Knuth is the
>> main guy in my field, and I know him very well (we've met on several
>> occasions, and I am one of 4 people in the world to proofread his
>> "Selected Papers" books before they are published, at Don's direct
>> request).
>>      If you guys decide to talk about Literate Programming in one of
>> the Perl meetings, I would probably be inspired to come!
>> Mark
>>      
> T gave a talk that included information about TELPS (The Extensible
> Literate Programming System) I'm developing.  It is pre-alpha and
> experimental.  I'll send another message out Sunday, 2010-03-21,
> about it.    -mark
>
>    

From jacoby at purdue.edu  Fri Mar 19 09:05:58 2010
From: jacoby at purdue.edu (David Jacoby)
Date: Fri, 19 Mar 2010 12:05:58 -0400
Subject: [Purdue-pm] Unicode Within Perl
Message-ID: <4BA3A0E6.5070705@purdue.edu>

After the last meeting, Mark, Joe and I talked a little about coding in
Unicode, among other things.

I have just tried some stuff quick. My go-to unicode symbol, u00b0 or ?,
the degree symbol, is rejected as a variable-name character. But pi, ?,
is accepted for variable names. Which is interesting.

#!/usr/bin/perl

use 5.010 ;
use utf8 ;
use strict ;
use warnings ;
binmode STDOUT , ':utf8' ;

my $? = 'pi' ;
say $? ;



-- 
Dave Jacoby                         Address: WSLR S049
Genomics Core Programmer            Mail:    jacoby at purdue.edu
Purdue University                   Phone:   765.49.67368

From mark at ecn.purdue.edu  Fri Mar 19 09:55:18 2010
From: mark at ecn.purdue.edu (Mark Senn)
Date: Fri, 19 Mar 2010 12:55:18 -0400
Subject: [Purdue-pm] Unicode Within Perl
In-Reply-To: <21593_1269014529_o2JG293o014590_4BA3A0E6.5070705@purdue.edu>
References: <21593_1269014529_o2JG293o014590_4BA3A0E6.5070705@purdue.edu>
Message-ID: <7248.1269017718@pier.ecn.purdue.edu>

  Dave Jacoby wrote at 2010-03-19 12:05:58 -0400:
  > After the last meeting, Mark, Joe and I talked a little about coding in
  > Unicode, among other things.
  > 
  > I have just tried some stuff quick. My go-to unicode symbol, u00b0 or ?,
  > the degree symbol, is rejected as a variable-name character. But pi, ?,
  > is accepted for variable names. Which is interesting.
  > 
  > #!/usr/bin/perl
  > 
  > use 5.010 ;
  > use utf8 ;
  > use strict ;
  > use warnings ;
  > binmode STDOUT , ':utf8' ;
  > 
  > my $? = 'pi' ;
  > say $? ;

Dave,    Does
    http://www.perlmonks.org/?node_id=793800
answer your question?    -mark

From mark at purdue.edu  Sun Mar 21 18:45:52 2010
From: mark at purdue.edu (Mark Senn)
Date: Sun, 21 Mar 2010 21:45:52 -0400
Subject: [Purdue-pm] Extensible Literate Programming in Perl
Message-ID: <12393.1269222352@pier.ecn.purdue.edu>

The FunnelWeb Tutorial Manual [1] has a good description of literate
programming:

    A traditional computer program consists of a text file containing
    program code. Scattered in amongst the program code are comments
    which describe the various parts of the code.

    In literate programming the emphasis is reversed. Instead of writing
    code containing documentation, the literate programmer writes
    documentation containing code. No longer does the English commentary
    injected into a program have to be hidden in comment delimiters at
    the top of the file, or under procedure headings, or at the end of
    lines. Instead, it is wrenched into the daylight and made the main
    focus. The "program" then becomes primarily a document directed at
    humans, with the code being herded between "code delimiters" from
    where it can be extracted and shuffled out sideways to the language
    system by literate programming tools.

    The effect of this simple shift of emphasis can be so profound as to
    change one's whole approach to programming. Under the literate
    programming paradigm, the central activity of programming becomes
    that of conveying meaning to other intelligent beings rather than
    merely convincing the computer to behave in a particular way. It is
    the difference between performing and exposing a magic trick.

I'm writing TELPS, The Extensible Literate Programming System.  I
mainly started working on it to better explain my solution to the
"PRE-CHRISTMAS SALE" Purdue Perl Mongers challenge problem.  The
commentary section can contain text and math notation using LaTeX and
graphics using MetaPost.  Other processors can be added easily (for
example, to call Mathematica to do some computations or graphics to
instert in the commentary).  See [2] for more information about TELPS
and an example.  I'll be improving it.

[1]  http://www.ross.net/funnelweb/tutorial/intro_what.html
[2]  http://www.sharpresearch.com/telps/

Mark Senn

From mark at sharpresearch.com  Sun Mar 21 19:08:04 2010
From: mark at sharpresearch.com (Mark Senn)
Date: Sun, 21 Mar 2010 21:08:04 -0500
Subject: [Purdue-pm] TELPS low volume mailing list
Message-ID: <20100321210804.h97s3g79k4gw48c0@webmail.sharpresearch.com>

Purdue Perl Mongers,

I'm sorry, I forgot a detail.  See
http://www.sharpresearch.com/telps
for instructions on how to sign up for a very low
volume TELPS (The Extensible Literate Programming System)
mailing list.  I don't plan to send TELPS information
to the Purdue Perl Mongers list in the future.

Mark Senn



From gizmo at purdue.edu  Tue Mar 23 20:30:27 2010
From: gizmo at purdue.edu (Joe Kline)
Date: Tue, 23 Mar 2010 23:30:27 -0400
Subject: [Purdue-pm] perl quotw
Message-ID: <4BA98753.1000209@purdue.edu>

-----BEGIN PGP SIGNED MESSAGE-----
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I looked through the quiz of the week archive (the first 6 or so
actually) and I think quiz 6 seems like a good challenge.

http://perl.plover.com/qotw/r/006

For those that are curious there were 2 qotw, regular and expert. The
complete archives are at:

Regular

http://perl.plover.com/qotw/r/

Expert
http://perl.plover.com/qotw/e/

These were sort of spearheaded by Mark-Jason Dominus

http://perl.plover.com/qotw/

joe
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From mdw at purdue.edu  Wed Mar 24 05:36:11 2010
From: mdw at purdue.edu (Mark Daniel Ward)
Date: Wed, 24 Mar 2010 08:36:11 -0400
Subject: [Purdue-pm] perl quotw
In-Reply-To: <4BA98753.1000209@purdue.edu>
References: <4BA98753.1000209@purdue.edu>
Message-ID: <4BAA073B.6030305@purdue.edu>

Dear Joe,
     Those qotw challenges were awesome!  I didn't know about them 
before, but this is very cool.  The next time that I'm teaching Perl in 
class, I could probably design some of the course challenges around 
things like that.  Wow, very cool!  Thank you for bringing those to 
everyone's attention.  Neat!  Thank you!
Mark



On 3/23/10 11:30 PM, Joe Kline wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> I looked through the quiz of the week archive (the first 6 or so
> actually) and I think quiz 6 seems like a good challenge.
>
> http://perl.plover.com/qotw/r/006
>
> For those that are curious there were 2 qotw, regular and expert. The
> complete archives are at:
>
> Regular
>
> http://perl.plover.com/qotw/r/
>
> Expert
> http://perl.plover.com/qotw/e/
>
> These were sort of spearheaded by Mark-Jason Dominus
>
> http://perl.plover.com/qotw/
>
> joe
> -----BEGIN PGP SIGNATURE-----
> Version: GnuPG v1.4.9 (GNU/Linux)
> Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/
>
> iEYEARECAAYFAkuph1IACgkQb0mzA2gRTplerACdGYf6ue0420QpGsdghYFqVSev
> mBMAnjsVovsPD0OAZ9sM8+FTHS+OPaAJ
> =BUHH
> -----END PGP SIGNATURE-----
> _______________________________________________
> Purdue-pm mailing list
> Purdue-pm at pm.org
> http://mail.pm.org/mailman/listinfo/purdue-pm
>
>    

From westerman at purdue.edu  Wed Mar 24 06:05:04 2010
From: westerman at purdue.edu (Rick Westerman)
Date: Wed, 24 Mar 2010 09:05:04 -0400
Subject: [Purdue-pm] perl quotw
In-Reply-To: <4BA98753.1000209@purdue.edu>
References: <4BA98753.1000209@purdue.edu>
Message-ID: <4BAA0E00.2040309@purdue.edu>

Joe Kline wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> I looked through the quiz of the week archive (the first 6 or so
> actually) and I think quiz 6 seems like a good challenge.
>
> http://perl.plover.com/qotw/r/006
>
>
>   
     Yes, that is a good one.  Let's use it for the April challenge.  I 
am not sure how we will judge the quality of the programs.  It seems to 
me (without actually having written the program) that the run time will 
be in the seconds (or less).   Perhaps we can judge on (a) "beauty" of 
the code and (b) robustness -- I have a couple ideas in regards to 
difficult or invalid input.   In any case this is suppose to be a 
learning exercise for all and not a "my code is better than your code" 
contest.

   See you April 20th!

-- 
Rick Westerman westerman at purdue.edu Bioinformatics specialist at the 
Genomics Facility. Phone: (765) 494-0505 FAX: (765) 496-7255 Department 
of Horticulture and Landscape Architecture 625 Agriculture Mall Drive 
West Lafayette, IN 47907-2010 Physically located in room S049, WSLR 
building

From mark at ecn.purdue.edu  Wed Mar 24 07:40:51 2010
From: mark at ecn.purdue.edu (Mark Senn)
Date: Wed, 24 Mar 2010 10:40:51 -0400
Subject: [Purdue-pm] perl quotw
In-Reply-To: <8721_1269435905_o2OD54PA013377_4BAA0E00.2040309@purdue.edu>
References: <4BA98753.1000209@purdue.edu>
	<8721_1269435905_o2OD54PA013377_4BAA0E00.2040309@purdue.edu>
Message-ID: <5474.1269441651@pier.ecn.purdue.edu>

  Rick Westerman <westerman at purdue.edu> wrote Wed, 24 Mar 2010 09:05:04 -0400
  > Yes, that is a good one.  Let's use it for the April challenge.  I
  > am not sure how we will judge the quality of the programs.  It seems
  > to me (without actually having written the program) that the run time
  > will be in the seconds (or less).   Perhaps we can judge on (a)
  > "beauty" of the code and (b) robustness -- I have a couple ideas in
  > regards to difficult or invalid input.   In any case this is suppose
  > to be a learning exercise for all and not a "my code is better than
  > your code" contest.
  > 
  > See you April 20th!

I'm not sure how we will judge the quality of the programs either.
The specs at
    http://perl.plover.com/qotw/r/006
are too loose.  Are only positive integers allowed?  Will format_number_list
input always use numbers instead of strings so wo don't have to worry
about positive integers specified as, for example, '--42'?  Will the input
to the functions always be in sorted order?  What should happen with no input?
What should expand_number_list do with zero length input?  And so on.

I suggest we use
    YES (is checked before function is called, smallest number used is 1,
        largest 1000---for extra credit, smallest number used is 1,
        largest a google (1 followed by 100 zeroes))
    YES (is checked before function is called)
    YES (so any sorting won't have to be part of any "Big O" discussions,
         sorted order checking is done before the functions are called)
    CAN'T HAPPEN (is checked by other code before the functions are called)
    CAN'T HAPPEN (is checked by other code before the functions are called)
    Other questions assume the simple case of specified input like the
    example with no other complications.

(I'll be doing a Big O (see http://en.wikipedia.org/wiki/Big_O_notation)
analysis of my solution for time and space.)

-mark

From gizmo at purdue.edu  Wed Mar 24 08:04:12 2010
From: gizmo at purdue.edu (Joe Kline)
Date: Wed, 24 Mar 2010 11:04:12 -0400
Subject: [Purdue-pm] perl quotw
In-Reply-To: <5474.1269441651@pier.ecn.purdue.edu>
References: <4BA98753.1000209@purdue.edu>	<8721_1269435905_o2OD54PA013377_4BAA0E00.2040309@purdue.edu>
	<5474.1269441651@pier.ecn.purdue.edu>
Message-ID: <4BAA29EC.2050805@purdue.edu>

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Mark Senn wrote:
>   Rick Westerman <westerman at purdue.edu> wrote Wed, 24 Mar 2010 09:05:04 -0400
>   > Yes, that is a good one.  Let's use it for the April challenge.  I
>   > am not sure how we will judge the quality of the programs.  It seems
>   > to me (without actually having written the program) that the run time
>   > will be in the seconds (or less).   Perhaps we can judge on (a)
>   > "beauty" of the code and (b) robustness -- I have a couple ideas in
>   > regards to difficult or invalid input.   In any case this is suppose
>   > to be a learning exercise for all and not a "my code is better than
>   > your code" contest.
>   > 
>   > See you April 20th!
> 
> I'm not sure how we will judge the quality of the programs either.
> The specs at
>     http://perl.plover.com/qotw/r/006
> are too loose.  Are only positive integers allowed?  Will format_number_list
> input always use numbers instead of strings so wo don't have to worry
> about positive integers specified as, for example, '--42'?  Will the input
> to the functions always be in sorted order?  What should happen with no input?
> What should expand_number_list do with zero length input?  And so on.
> 
> I suggest we use
>     YES (is checked before function is called, smallest number used is 1,
>         largest 1000---for extra credit, smallest number used is 1,
>         largest a google (1 followed by 100 zeroes))
>     YES (is checked before function is called)
>     YES (so any sorting won't have to be part of any "Big O" discussions,
>          sorted order checking is done before the functions are called)
>     CAN'T HAPPEN (is checked by other code before the functions are called)
>     CAN'T HAPPEN (is checked by other code before the functions are called)
>     Other questions assume the simple case of specified input like the
>     example with no other complications.
> 

- From a brief look at the qotw discussion archive stuff like this left to
the implementer.

If your program can handle negative numbers so much the better.

If mine barfs on null input...well that sucks.

Constraining the problem constrains the coder. :-)

This is Perl after all, TIMTOWTDI.

joe

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From gizmo at purdue.edu  Wed Mar 24 08:06:41 2010
From: gizmo at purdue.edu (Joe Kline)
Date: Wed, 24 Mar 2010 11:06:41 -0400
Subject: [Purdue-pm] perl quotw
In-Reply-To: <5474.1269441651@pier.ecn.purdue.edu>
References: <4BA98753.1000209@purdue.edu>	<8721_1269435905_o2OD54PA013377_4BAA0E00.2040309@purdue.edu>
	<5474.1269441651@pier.ecn.purdue.edu>
Message-ID: <4BAA2A81.1070509@purdue.edu>

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I forgot to add some links to the discussion thread.

General quiz questions and possible problem with current quiz
http://article.gmane.org/gmane.comp.lang.perl.qotw.discuss/719

Re: General quiz questions and possible problem with current quiz
http://article.gmane.org/gmane.comp.lang.perl.qotw.discuss/722

Re: General quiz questions and possible problem with current quiz
http://article.gmane.org/gmane.comp.lang.perl.qotw.discuss/720

Re: General quiz questions and possible problem with current quiz
http://article.gmane.org/gmane.comp.lang.perl.qotw.discuss/725



General quiz questions and possible problem with current quiz

http://news.gmane.org/gmane.comp.lang.perl.qotw.discuss

The week 6 discussion is in page 11.

joe
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From gribskov at purdue.edu  Wed Mar 24 08:59:15 2010
From: gribskov at purdue.edu (Michael Gribskov)
Date: Wed, 24 Mar 2010 11:59:15 -0400
Subject: [Purdue-pm] perl quotw
In-Reply-To: <4BAA2A81.1070509@purdue.edu>
References: <4BA98753.1000209@purdue.edu>	<8721_1269435905_o2OD54PA013377_4BAA0E00.2040309@purdue.edu>	<5474.1269441651@pier.ecn.purdue.edu>
	<4BAA2A81.1070509@purdue.edu>
Message-ID: <4BAA36D3.2000801@purdue.edu>

here is a test program you might use.  the data, if i did it right has 
all possible transitions from singleton to singleton, singleton to 
range, range to range, and range to singleton
use strict;

my @datalist = (    [],
                    [1, 4, 5, 6, 9, 13, 21, 22, 23, 25, 26, 27],
                    [1, 2, 3, 5, 6, 7, 9, 13, 15, 16, 17, 27],
                    [-27, -17, -16, -15, -13, -9, -7, -6, -5, -3, -2, -1],
                    [-27, -26, -25, -23, -22, -21, -13, -9, -6, -5, -4, -1],
                    [-8, -6, -5, -4, 9, 13, 21, 22, 23, 25, 26, 27],
                    [-6, -5, -4, 5, 6, 7, 9, 13, 15, 16, 17, 27],
                    [-8, -6, -5, -4, 0, 9, 13, 21, 22, 23, 25, 26, 27],
                    [-6, -5, -4, 5, 9, 6, 7, 9, 13, 15, 16, 17, 27]
                   
               );
              
my @datacomment = ( 'null list',
                    'begins with singleton, ends with range',
                    'begins with range, ends with singleton',
                    'negative numbers, begin with singleton, end with 
range',
                    'negative numbers, begin with range, end with 
singleton',
                    'negative & positive numbers, begin with singleton, 
end with range',
                    'negative & positive numbers, begin with range, end 
with singleton',
                    'negative & positive numbers & zero, begin with 
singleton, end with range',
                    'negative & positive numbers & zero, begin with 
range, end with singleton',
                  );
foreach my $d ( 0 .. $#datalist ) {
   
    my @data = @{$datalist[$d]};
    print "\ntest $d: $datacomment[$d]\n";
    print "    data = [ @data ]\n";
   
    print "      original number list: @data\n";
   
    my $numstring = formatNumberList( @data );
    print "     formatted number list: $numstring\n";
   
    my @newlist = expandNumberList( $numstring );
    print "    converted back to list: @newlist\n";

}


Joe Kline wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> I forgot to add some links to the discussion thread.
>
> General quiz questions and possible problem with current quiz
> http://article.gmane.org/gmane.comp.lang.perl.qotw.discuss/719
>
> Re: General quiz questions and possible problem with current quiz
> http://article.gmane.org/gmane.comp.lang.perl.qotw.discuss/722
>
> Re: General quiz questions and possible problem with current quiz
> http://article.gmane.org/gmane.comp.lang.perl.qotw.discuss/720
>
> Re: General quiz questions and possible problem with current quiz
> http://article.gmane.org/gmane.comp.lang.perl.qotw.discuss/725
>
>
>
> General quiz questions and possible problem with current quiz
>
> http://news.gmane.org/gmane.comp.lang.perl.qotw.discuss
>
> The week 6 discussion is in page 11.
>
> joe
> -----BEGIN PGP SIGNATURE-----
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>
> iD8DBQFLqiqAb0mzA2gRTpkRArvFAJ95Pad2Iqx/+dO1XjvGj0jFpztb/wCfVyBU
> b6t6qItdwBa//Eb/kZdxkFQ=
> =/g2R
> -----END PGP SIGNATURE-----
> _______________________________________________
> Purdue-pm mailing list
> Purdue-pm at pm.org
> http://mail.pm.org/mailman/listinfo/purdue-pm
>   


-- 
Michael Gribskov
Hockmeyer Hall of Structural Biology
Purdue University
240 S. Martin Jischke Drive
West Lafayette, IN 47907

gribskov at purdue.edu     vox: 765.494.6933     fax: 765.496-1189
calendar: http://www.google.com/calendar/embed?src=mgribskov%40gmail.com





From gribskov at purdue.edu  Wed Mar 24 10:08:06 2010
From: gribskov at purdue.edu (Michael Gribskov)
Date: Wed, 24 Mar 2010 13:08:06 -0400
Subject: [Purdue-pm] my solution to challenge
In-Reply-To: <4BAA2A81.1070509@purdue.edu>
References: <4BA98753.1000209@purdue.edu>	<8721_1269435905_o2OD54PA013377_4BAA0E00.2040309@purdue.edu>	<5474.1269441651@pier.ecn.purdue.edu>
	<4BAA2A81.1070509@purdue.edu>
Message-ID: <4BAA46F6.9050604@purdue.edu>

#!/usr/bin/perl -w
#------------------------------------------------------------------------------
# $Id:$
#
# Write a function, format_number_list, whose argument is a list of
# integers.  It then returns a string which represents the input list in
# compact, human-readable form.
#
# For example,
#         format_number_list(1, 2, 4, 5, 6, 7, 9, 13, 24, 25, 26, 27)
# will return
#        "1-2, 4-7, 9, 13, 24-27"
#
# Also write a function, 'expand_number_list', which does the conversion
# in the opposite direction, so that
#        expand_number_list("1-2, 4-7, 9, 13, 24-27")
# will return
#        (1, 2, 4, 5, 6, 7, 9, 13, 24, 25, 26, 27)
#
# Michael Gribskov     Mar 24, 2010
#
# Revision log at end of file
#------------------------------------------------------------------------------
use strict;

my @datalist = (    [],
                    [1, 4, 5, 6, 9, 13, 21, 22, 23, 25, 26, 27],
                    [1, 2, 3, 5, 6, 7, 9, 13, 15, 16, 17, 27],
                    [-27, -17, -16, -15, -13, -9, -7, -6, -5, -3, -2, -1],
                    [-27, -26, -25, -23, -22, -21, -13, -9, -6, -5, -4, -1],
                    [-8, -6, -5, -4, 9, 13, 21, 22, 23, 25, 26, 27],
                    [-6, -5, -4, 5, 6, 7, 9, 13, 15, 16, 17, 27],
                    [-8, -6, -5, -4, 0, 9, 13, 21, 22, 23, 25, 26, 27],
                    [-6, -5, -4, 0, 5, 9, 6, 7, 9, 13, 15, 16, 17, 27]
                   
               );
              
my @datacomment = ( 'null list',
                    'begins with singleton, ends with range',
                    'begins with range, ends with singleton',
                    'negative numbers, begin with singleton, end with 
range',
                    'negative numbers, begin with range, end with 
singleton',
                    'negative & positive numbers, begin with singleton, 
end with range',
                    'negative & positive numbers, begin with range, end 
with singleton',
                    'negative & positive numbers & zero, begin with 
singleton, end with range',
                    'negative & positive numbers & zero, begin with 
range, end with singleton',
                  );
foreach my $d ( 0 .. $#datalist ) {
   
    my @data = @{$datalist[$d]};
    print "\ntest $d: $datacomment[$d]\n";
    print "    data = [ @data ]\n";
   
    print "      original number list: @data\n";
   
    my $numstring = formatNumberList( @data );
    print "     formatted number list: $numstring\n";
   
    my @newlist = expandNumberList2( $numstring );
    print "    converted back to list: @newlist\n";

}

#------------------------------------------------------------------------------
# formatNumberList
#
# converts a list of numbers to a string where successive numbers are 
given as
# as a range with a hyphen, e.g.,  2,3,4 becomes 2-4.  Works with negative
# numbers and zero, but produces an ugly double hyphen.  The input 
should be
# presorted
#
# USAGE
#    $formatted_string = formatNumberList( @list );
#------------------------------------------------------------------------------
sub formatNumberList{
   
    return "" unless @_;        # return empty string for null input
   
    my $n = shift;
    my $str = $n;
    my $end;
    my $next = $n + 1;
   
    # $end is a marker that tells a range has ben opened, and gives the 
current
    # end of the range.  if $end is undef, the current number either 
begins a
    # range or is a singleton.
   
    while ( @_ ) {
       
        $n = shift;
       
        if ( $n==$next ) {
            # begin a new range
            $str .= "-" unless $end;
            $end = $n;
        } else {
            # end of a range, or a singleton
            $str .= sprintf "%s, %d", $end||"", $n;
            undef $end;
        }
        $next = $n+1;
    }
    $str .= $end if $end;      # close last range if it is a range
   
    return $str;
}

# End of formatNumberList

#------------------------------------------------------------------------------
# expandNumberList
#
# convert the string produced by formatNumberList back to a list.  This 
version
# only works for positive numbers.
#
# USAGE
#   @list_of_numbers = expandNumberList( $number_list_string );
#------------------------------------------------------------------------------
sub expandNumberList{
    my ( $numstring ) = @_;
    my @numlist;
   
    my @range = split /\s*,\s*/, $numstring;      # split on comma with 
spaces
   
    foreach my $r ( @range ) {
        my ( $begin, $end ) = split "-", $r;       
        unless ( defined $end ) {                 # $end is undef if not 
a range
            $end = $begin;
        }
        foreach my $i ( $begin .. $end ) {
            push @numlist, $i;
        }
    }
   
    return @numlist;
}

# End of expandNumberList

#------------------------------------------------------------------------------
# expandNumberList2
#
# convert the string produced by formatNumberList back to a list.  This 
version
# workks for zero, positive, and negative numbers
#
# USAGE
#   @list_of_numbers = expandNumberList( $number_list_string );
#------------------------------------------------------------------------------
sub expandNumberList2{
    my ( $numstring ) = @_;
    my @numlist;
   
    # break string up into ranges and singletons by splitting on 
commas.  just
    # in case, allow space around the commas
   
    my @range = split /\s*,\s*/, $numstring;    
   
    foreach my $r ( @range ) {
       
        # get begin and end of range, if its a singleton, begin and end 
are the same
       
        my $begin = $r;
        my $end = $r;
       
        if ( $r =~ /\d-/ ) {                      # test if this is a range
           
           # convert negative signs to x, to protect from split
           $r =~ s/^-/x/;
           $r =~ s/--/-x/;
       
           # split and convert x back to negative
           ( $begin, $end ) = split "-", $r;       
           $begin =~ s/x/-/;
           $end =~ s/x/-/;
        }
               
           # push range onto list. 
          
           foreach my $i ( $begin .. $end ) {
           push @numlist, $i;
        }
          
    }
   
    return @numlist;
}

# End of expandNumberList2
#------------------------------------------------------------------------------
# $Log:$
#------------------------------------------------------------------------------

-- 
Michael Gribskov
Hockmeyer Hall of Structural Biology
Purdue University
240 S. Martin Jischke Drive
West Lafayette, IN 47907

gribskov at purdue.edu     vox: 765.494.6933     fax: 765.496-1189
calendar: http://www.google.com/calendar/embed?src=mgribskov%40gmail.com





From gizmo at purdue.edu  Thu Mar 25 08:04:26 2010
From: gizmo at purdue.edu (Joe Kline)
Date: Thu, 25 Mar 2010 11:04:26 -0400
Subject: [Purdue-pm] deep copies
Message-ID: <4BAB7B7A.2090408@purdue.edu>

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I think Dave was asking about making copies of data structures some time
back.

The Effective Perler addressed that this week:

http://www.effectiveperlprogramming.com/blog/85

joe
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From mark at purdue.edu  Fri Mar 26 04:48:44 2010
From: mark at purdue.edu (Mark Senn)
Date: Fri, 26 Mar 2010 07:48:44 -0400
Subject: [Purdue-pm] Google Summer of Code
Message-ID: <15892.1269604124@pier.ecn.purdue.edu>

The Purdue chapter of the Purdue Perl Mongers was sent the following message.
The Purdue Perl Mongers is a Perl users group.  Our homepage is at
    http://pm.purdue.org
Mark Senn

>Date: Fri, 26 Mar 2010 03:50:55 -0700
>From: Eric Wilhelm <scratchcomputing at gmail.com>
>To: pm_groups at pm.org
>Cc: Jerry Gay <jerry.gay+soc2010 at gmail.com>, Jonathan Leto <jaleto at gmail.com>
>Subject: [pm_groups] Google Summer of Code and TPF call for students
>
>Hi Perl Mongers,
>
>TPF is participating in GSoC 2010 and will begin accepting applications 
>from students on the 29th.  Please share this info with your groups and 
>local academic contacts.
>
>If you are a college student interested in Open Source software, now is 
>the time to get involved.
>
>  http://code.google.com/soc/
>
>Each year, Google offers students the opportunity to spend their summer 
>coding on open source projects. You propose a project, and if selected, 
>you're assigned a mentor and provided a $4500 stipend. It is a 
>competitive program to get into, but offers an amazing amount of 
>real-world experience and the ability to get seriously involved in an 
>open source project of your choosing. The Perl Foundation spans a wide 
>variety of projects including Perl 5, Perl 6, and Parrot with many 
>great mentors knowledgeable in areas ranging from language design, 
>virtual machines, and compilers through web and desktop applications. 
>This program is a great chance to get more involved in the Perl 
>community and put a substantial project worth of source code in your 
>portfolio.
>
>Applications are due April 9th.
>
>  http://www.perlfoundation.org/perl5/index.cgi?gsoc
>
>Thanks,
>Eric
>-- 
>http://pdx.pm.org

From mark at sharpresearch.com  Sat Mar 27 17:08:05 2010
From: mark at sharpresearch.com (Mark Senn)
Date: Sat, 27 Mar 2010 19:08:05 -0500
Subject: [Purdue-pm] my challenge problem solution
Message-ID: <20100327190805.nnx9xf3hkwows4k4@webmail.sharpresearch.com>

Here is my solution to the latest challenge problem.
It assumes that all input to the two subs we were
asked to write is sanity checked outside of of those subs.

-mark


From mark at purdue.edu  Sat Mar 27 17:42:20 2010
From: mark at purdue.edu (Mark Senn)
Date: Sat, 27 Mar 2010 20:42:20 -0400
Subject: [Purdue-pm] take 2: challenge problem solution
Message-ID: <10707.1269736940@pier.ecn.purdue.edu>

Sorry for zero-length attachment in previous message.

Below is my solution to the latest challenge problem.
It assumes that all input to the two subs we were
asked to write is sanity checked outside of of those subs.

-mark

#!/usr/bin/perl

use Modern::Perl;

#
#  From http://perl.plover.com/qotw/r/006 retrieved on 2010-03-27:
#
#      Write a function, format_number_list, whose argument is a list of
#      integers.  It then returns a string which represents the input list in
#      compact, human-readable form.
#
#      For example,
#
#               format_number_list(1, 2, 4, 5, 6, 7, 9, 13, 24, 25, 26, 27)
#
#      will return
#
#              "1-2, 4-7, 9, 13, 24-27"
#
#      Also write a function, 'expand_number_list', which does the conversion
#      in the opposite direction, so that
#
#              expand_number_list("1-2, 4-7, 9, 13, 24-27")
#
#      will return
#
#              (1, 2, 4, 5, 6, 7, 9, 13, 24, 25, 26, 27)
#
#  From Michael Gribskov on 2010-03-24 (slightly edited to keep most lines
#  less than 80 characters):
#
#      my @datalist = ( [],
#          [1, 4, 5, 6, 9, 13, 21, 22, 23, 25, 26, 27],
#          [1, 2, 3, 5, 6, 7, 9, 13, 15, 16, 17, 27],
#          [-27, -17, -16, -15, -13, -9, -7, -6, -5, -3, -2, -1],
#          [-27, -26, -25, -23, -22, -21, -13, -9, -6, -5, -4, -1],
#          [-8, -6, -5, -4, 9, 13, 21, 22, 23, 25, 26, 27],
#          [-6, -5, -4, 5, 6, 7, 9, 13, 15, 16, 17, 27],
#          [-8, -6, -5, -4, 0, 9, 13, 21, 22, 23, 25, 26, 27],
#          [-6, -5, -4, 5, 9, 6, 7, 9, 13, 15, 16, 17, 27]
#      );
#      my @datacomment = ( 'null list',
#          'begins with singleton, ends with range',
#          'begins with range, ends with singleton',
#          'negative numbers, begin with singleton, end with range',
#          'negative numbers, begin with range, end with singleton',
#          'negative & positive numbers, begin with singleton, end with range',
#          'negative & positive numbers, begin with range, end with singleton',
#          'negative & positive numbers & zero, begin with singleton, end with range',
#          'negative & positive numbers & zero, begin with range, end with singleton',
#      );
#      foreach my $d ( 0 .. $#datalist ) {
#          my @data = @{$datalist[$d]};
#          print "\ntest $d: $datacomment[$d]\n";
#          print "    data = [ @data ]\n";
#          print "      original number list: @data\n";
#          my $numstring = formatNumberList( @data );
#          print "     formatted number list: $numstring\n";
#          my @newlist = expandNumberList( $numstring );
#          print "    converted back to list: @newlist\n";
#
#      }
#
#  I think the time and space needed for the program below are both order n,
#  assuming perl's range operator is implemented reasonably.
#


#
#  Pair - format a begin/end pair
#
#  Return "", "$begin", or "$begin-$end"
#  depending on values of $begin and $end.
#

sub Pair
{
    my ($begin, $end) = @_;
    my $r = $begin // '';
    ($end != $begin)  and  $r .= "-$end";
    return $r;
}


#
#  expand_number_list - expand number list to array
#
#  Expand, for example,
#      "1-2, 4-7, 9, 13, 24-27"
#  to
#      (1, 2, 4, 5, 6, 7, 9, 13, 24, 25, 26, 27)
#
#  VARIABLE    DESCRIPTION
#  $begin      value that starts a singleton or a range
#  $end        value that ends a singleton or a range
#  @r          resulting components, 1, 2, 4, ... in above example
#

sub expand_number_list
{
    my @item = split /,\s*/, $_[0];
    my ($begin, $end);
    my @r = ();
    foreach (@item)
    {
        (/^(-?\d+)$/)          and  $begin = $1, $end = $1;
        (/^(-?\d+)-(-?\d+)$/)  and  $begin = $1, $end = $2;
        push @r, $begin..$end;
    }
    return @r;
}


#
#  format_number_list - reduce an array to a number list
#
#  Reduce, for example,
#      (1, 2, 4, 5, 6, 7, 9, 13, 24, 25, 26, 27)
#  to
#      "1-2, 4-7, 9, 13, 24-27"
#
#  I used the nested ternary operators instead of nested if-then-else's
#  because I thought that was more readable.  Using if-then-else's would
#  have buried the actions to take in a lot more syntax.
#
#  VARIABLE    DESCRIPTION
#  $begin      value that starts a singleton or a range
#  $end        value that ends a singleton or a range
#  @r          resulting components, "1-2", "4-7", "9", ... in above example
#

sub format_number_list
{
    my @r = ();
    my $begin = my $end = undef;
    foreach (@_)
    {
        (defined $begin)
            ?  ($_ == $end+1)
                   ?  do {  $end = $_;                                        }
                   :  do {  push @r, Pair $begin, $end;  $begin = $end = $_;  }
            :  do {  $begin = $end = $_;  }
    }
    (defined $begin)  and  push @r, Pair $begin, $end;
    return join ', ', @r;
}


#
#  main program
#

my $sepline = '-' x 40;  # line to separate lines of output
while (<DATA>)
{
    chomp;
    my @data0 = split /,\s*/;
    my $data1 = format_number_list @data0;
    my @data2 = expand_number_list $data1;
    say $sepline;
    say "data read:                @data0";
    say "after expand number_list: @data2";
    say "after format_number_list: $data1";
    ((join ' ', @data0) ne (join ' ', @data2))
        and  die "data0 and data2 are different";
    say $sepline;
}


#
#  All of this data except the last two lines is from Michael Gribskov.
#

__DATA__

1, 4, 5, 6, 9, 13, 21, 22, 23, 25, 26, 27
1, 2, 3, 5, 6, 7, 9, 13, 15, 16, 17, 27
-27, -17, -16, -15, -13, -9, -7, -6, -5, -3, -2, -1
-27, -26, -25, -23, -22, -21, -13, -9, -6, -5, -4, -1
-8, -6, -5, -4, 9, 13, 21, 22, 23, 25, 26, 27
-6, -5, -4, 5, 6, 7, 9, 13, 15, 16, 17, 27
-8, -6, -5, -4, 0, 9, 13, 21, 22, 23, 25, 26, 27
-6, -5, -4, 5, 9, 6, 7, 9, 13, 15, 16, 17, 27
-1, 0, 1
0

From mark at purdue.edu  Sat Mar 27 19:48:25 2010
From: mark at purdue.edu (Mark Senn)
Date: Sat, 27 Mar 2010 22:48:25 -0400
Subject: [Purdue-pm] tweak to program
Message-ID: <21044.1269744505@pier.ecn.purdue.edu>

The program I sent earlier had
    (/^(-?\d+)$/)          and  $begin = $1, $end = $1;
    (/^(-?\d+)-(-?\d+)$/)  and  $begin = $1, $end = $2;
    push @r, $begin..$end;
I changed that to
    /^(-?\d+)(?:-(-?\d+))?$/;
    $begin = $1;
    $end = $2 // $1;
    push @r, $begin..$end;
because I think that expresses it better, even though the regular
expression is more complex.  (I usually don't use the "group but don't
capture"
    (?: ... )
because I don't like that syntax and instead capture everything even if
it is not used later.)

The $2 // $1 means use the value of $2 if it is set, otherwise use the
value of $1.

This code is hard to read if one hasn't seen this technique before but
what I'm trying to express maps nicely to this code.

-mark

From mark at purdue.edu  Sat Mar 27 20:06:27 2010
From: mark at purdue.edu (Mark Senn)
Date: Sat, 27 Mar 2010 23:06:27 -0400
Subject: [Purdue-pm] Perl6 Periodic Table of the Operators
Message-ID: <22101.1269745587@pier.ecn.purdue.edu>

See
    http://www.ozonehouse.com/mark/periodic/
for free 8 1/4 x 11 3/4 inch JPEG Perl6 Periodic Table of
the Operators and some expensive posters bigger than that.

Perl6's // operator has been added to Perl5.

Mark Lentczner updated this poster in February, 2009.

Disclosure: I don't know Mark, don't make any money
from this, etc.

-mark