Re: Amazing Perl 6
On Sun, May 31, 2009 at 04:45:12PM -0400, Brandon S. Allbery KF8NH wrote: On May 29, 2009, at 15:43 , John M. Dlugosz wrote: Care to try ☃ ? That's alt-meta-hyper-doublebucky-cokebottle. *puzzled as to why OSX Character Map thinks that's related to 雪* Maybe they can't tell the diffence between snowman and snow? (By the way, if you know any 日本人 named Yuki, they probably write their name with 雪. Which is a really cool (no pun intended) character--if you look at the two radicals, it basically means precipitation you can grasp. :) Larry
Re: Amazing Perl 6
On May 27, 2009, at 13:59 , Daniel Carrera wrote: Wow... That's a foldl! In a functional language, that would be called a fold. It's very popular in Haskell. I like that Perl 6 seems to be taking steps in the direction of functional languages. First lazy lists (0..Inf) and now a fold. :-D One of the early P6 prototypes was written in Haskell, and there's been a lot of notions lifted from it. (OTOH being an old phart I know [OP] @list as op/list :) -- brandon s. allbery [solaris,freebsd,perl,pugs,haskell] allb...@kf8nh.com system administrator [openafs,heimdal,too many hats] allb...@ece.cmu.edu electrical and computer engineering, carnegie mellon universityKF8NH PGP.sig Description: This is a digitally signed message part
Re: Amazing Perl 6
On May 27, 2009, at 15:42 , Daniel Carrera wrote: Mark J. Reed wrote: Note that of the examples given, only Perl 6 and Common Lisp do two things that help immensely simplify the result: 1. reference the built-in * operator directly, without having to wrap it in a lambda expression; 2. actually name the function ! Yes, very neat. Haskell does that too, but I don't know if you can make the function a postfix in Haskell. Not in H98, but ghc allows it as a degenerate form of section. -- brandon s. allbery [solaris,freebsd,perl,pugs,haskell] allb...@kf8nh.com system administrator [openafs,heimdal,too many hats] allb...@ece.cmu.edu electrical and computer engineering, carnegie mellon universityKF8NH PGP.sig Description: This is a digitally signed message part
Re: Amazing Perl 6
On May 27, 2009, at 18:05 , John M. Dlugosz wrote: And APL calls it |¨ (two little dots high up) buh? Metaoperator / (+/LIST). -- brandon s. allbery [solaris,freebsd,perl,pugs,haskell] allb...@kf8nh.com system administrator [openafs,heimdal,too many hats] allb...@ece.cmu.edu electrical and computer engineering, carnegie mellon universityKF8NH PGP.sig Description: This is a digitally signed message part
Re: Amazing Perl 6
On May 28, 2009, at 06:43 , Jon Lang wrote: What I'm wondering is how the list knows to feed two items into '[+]'. While 'infix:+' must accept exactly two arguments, '[+]' can accept an arbitrarily long (or short) list of arguments. I thought that at first too, then remembered a discussion about generalizing the meaning of square brackets and how [op] fell out of it automatically to take a reference to an operator without using the infix:op syntax. -- brandon s. allbery [solaris,freebsd,perl,pugs,haskell] allb...@kf8nh.com system administrator [openafs,heimdal,too many hats] allb...@ece.cmu.edu electrical and computer engineering, carnegie mellon universityKF8NH PGP.sig Description: This is a digitally signed message part
Re: Amazing Perl 6
On May 29, 2009, at 15:43 , John M. Dlugosz wrote: Care to try ☃ ? That's alt-meta-hyper-doublebucky-cokebottle. *puzzled as to why OSX Character Map thinks that's related to 雪* -- brandon s. allbery [solaris,freebsd,perl,pugs,haskell] allb...@kf8nh.com system administrator [openafs,heimdal,too many hats] allb...@ece.cmu.edu electrical and computer engineering, carnegie mellon universityKF8NH PGP.sig Description: This is a digitally signed message part
Re: Amazing Perl 6
On May 29, 2009, at 21:50 , Timothy S. Nelson wrote: some Linux programs support it too. Unfortunately my e-mail program (Pine) seems to have some trouble with unicode -- I may have to look at alternatives after 14 years of use :(. http://www.washington.edu/alpine/ -- brandon s. allbery [solaris,freebsd,perl,pugs,haskell] allb...@kf8nh.com system administrator [openafs,heimdal,too many hats] allb...@ece.cmu.edu electrical and computer engineering, carnegie mellon universityKF8NH PGP.sig Description: This is a digitally signed message part
Re: Amazing Perl 6
On May 29, 2009, at 22:40 , Timothy S. Nelson wrote: On Fri, 29 May 2009, John M. Dlugosz wrote: Ah yes, on the PC historically you hold down the ALT key and type the code with the numpad keys. At least when I used it, this was a decimal, rather than hex number, and had to be preceded by a 0 (zero). I see ALT+ a lot in Windows stuff, and have used it a few times (that is, while holding Alt type + and 4 hex digits). -- brandon s. allbery [solaris,freebsd,perl,pugs,haskell] allb...@kf8nh.com system administrator [openafs,heimdal,too many hats] allb...@ece.cmu.edu electrical and computer engineering, carnegie mellon universityKF8NH PGP.sig Description: This is a digitally signed message part
Re: Amazing Perl 6
The same tradition has variations in Windows. I recall the leading zero means ANSI code page. I thought I recall a way to give more digits and specify Unicode, but I can't find it on Google. --John Timothy S. Nelson wayland-at-wayland.id.au |Perl 6| wrote: On Fri, 29 May 2009, John M. Dlugosz wrote: Ah yes, on the PC historically you hold down the ALT key and type the code with the numpad keys. At least when I used it, this was a decimal, rather than hex number, and had to be preceded by a 0 (zero). So if anyone is still on eg. Windows 98, this may be the way to go :). - | Name: Tim Nelson | Because the Creator is,| | E-mail: wayl...@wayland.id.au| I am | - BEGIN GEEK CODE BLOCK Version 3.12 GCS d+++ s+: a- C++$ U+++$ P+++$ L+++ E- W+ N+ w--- V- PE(+) Y+++ PGP-+++ R(+) !tv b++ DI D G+ e++ h! y- -END GEEK CODE BLOCK-
Amazing Perl 6
Assuming you have the right key set in the Registry, you can enter hex Unicode in Windows. Hold down alt, press the + key on the numpad and then type the hex code (using the main keyboard and/or the numpad), then release alt. On Sat, May 30, 2009 at 2:11 AM, John M. Dlugosz j...@dlugosz.com wrote: The same tradition has variations in Windows. I recall the leading zero means ANSI code page. I thought I recall a way to give more digits and specify Unicode, but I can't find it on Google. --John Timothy S. Nelson wayland-at-wayland.id.au |Perl 6| wrote: On Fri, 29 May 2009, John M. Dlugosz wrote: Ah yes, on the PC historically you hold down the ALT key and type the code with the numpad keys. At least when I used it, this was a decimal, rather than hex number, and had to be preceded by a 0 (zero). So if anyone is still on eg. Windows 98, this may be the way to go :). - | Name: Tim Nelson | Because the Creator is, | | E-mail: wayl...@wayland.id.au | I am | - BEGIN GEEK CODE BLOCK Version 3.12 GCS d+++ s+: a- C++$ U+++$ P+++$ L+++ E- W+ N+ w--- V- PE(+) Y+++ PGP-+++ R(+) !tv b++ DI D G+ e++ h! y- -END GEEK CODE BLOCK- -- Mark J. Reed markjr...@gmail.com -- Mark J. Reed markjr...@gmail.com
Re: Amazing Perl 6
· Quoth Larry: ˸ So let’s not make the mistake of thinking something ˸ longer is always less confusing or more official. ⋮ I already have too much problem with people thinking the ⋮ efficiency of a perl construct is related to its length. So you’re saying the Law of Parsimony has its uses… a̲n̲d̲ abuses? ☻ --tom -- ENTIA NON · SVNT M V L T I P L I C A N D A PRÆTER N̳E̳C̳E̳S̳S̳I̳T̳A̳T̳E̳M̳
Re: Amazing Perl 6
On Thu, May 28, 2009 at 08:10:41PM -0500, John M. Dlugosz wrote: John Macdonald john-at-perlwolf.com |Perl 6| wrote: However, the assumption fails if process is supposed to mean that everyone is capable of generating Unicode in the messages that they are writing. I don't create non-English text often enough to have it yet be useful to learn how. (I'd just forget faster than I'd use it and have to learn it again each time - but Perl 6 might just be the tipping point to make learning Unicode composition worthwhile.) Just copy/paste from another message or a web page. Perhaps a web page designed for that purpose... Yep, I've done that. But comparing the difference in effort between: - press a key - Google for a web page that has the right character set, cut, refocus, paste means that I don't bother for the one or two weird characters every few months that is my current Unicode usage. If I were working with Unicode frequently, it would be worth setting up links and mechanisms, or learning the keyboard compose sequences for frequently used characters. I'm sure that there are many people in a similar situation.
Re: Amazing Perl 6
On Fri, May 29, 2009 at 6:52 AM, John Macdonald j...@perlwolf.com wrote: Yep, I've done that. But comparing the difference in effort between: - press a key - Google for a web page that has the right character set, cut, refocus, paste means that I don't bother for the one or two weird characters every few months that is my current Unicode usage. If I were working with Unicode frequently, it would be worth setting up links and mechanisms, or learning the keyboard compose sequences for frequently used characters. I'm sure that there are many people in a similar situation. Agreed. Given the frequency with which « and » come up in Perl 6, I'd love to be able to have a simple keyboard shortcut that produces these two characters. Unfortunately, I am often stuck using a Windows system when coding; and the easiest method that I have available to me there (that I know of) is to pull up Character Map. -- Jonathan Dataweaver Lang
Re: Amazing Perl 6
On Fri, May 29, 2009 at 10:23 AM, Jon Lang datawea...@gmail.com wrote: On Fri, May 29, 2009 at 6:52 AM, John Macdonald j...@perlwolf.com wrote: Yep, I've done that. But comparing the difference in effort between: - press a key - Google for a web page that has the right character set, cut, refocus, paste means that I don't bother for the one or two weird characters every few months that is my current Unicode usage. If I were working with Unicode frequently, it would be worth setting up links and mechanisms, or learning the keyboard compose sequences for frequently used characters. I'm sure that there are many people in a similar situation. Agreed. Given the frequency with which « and » come up in Perl 6, I'd love to be able to have a simple keyboard shortcut that produces these two characters. Unfortunately, I am often stuck using a Windows system when coding; and the easiest method that I have available to me there (that I know of) is to pull up Character Map. In response to this thread, I activated the US International keyboard layout, and once that's done theoretically one can get Spanish style quote mark with RightAlt+[ and RightAlt+] like so: « and ». The questions which remain (for me, at least) is if (a) the symbols survive in email, and (b) if they really are the proper marks for Perl6. -- Jonathan Dataweaver Lang
Re: Amazing Perl 6
Jon Lang wrote: Agreed. Given the frequency with which « and » come up in Perl 6, I'd love to be able to have a simple keyboard shortcut that produces these two characters. Unfortunately, I am often stuck using a Windows system when coding; and the easiest method that I have available to me there (that I know of) is to pull up Character Map Set your keyboard to us-international. There's a bunch of goodies in there. The problem is the delayed keystrokes on composed accented characters, formed by quote+letter. (like 'a) So write your own keyboard module. I did one for P6 several years ago. In the mean time, it's alt+shift, altgr+[ =Austin
Re: Amazing Perl 6
On Fri, May 29, 2009 at 10:56 AM, Austin Hastings austin_hasti...@yahoo.com wrote: Agreed. Given the frequency with which « and » come up in Perl 6, I'd love to be able to have a simple keyboard shortcut that produces these two characters. Windows; set keyboard to US-International. Right-alt + [ and ]. Mac (standard US keyboard): option + \ for «, same key shifted for » Linux: Lots of variables: X input manager, modifier keymap, etc. But digraphs work in vim: control-K and control-K -- Mark J. Reed markjr...@gmail.com
Re: Amazing Perl 6
Back to the question of cool things about perl6- after showing some
of the extended syntax and its expressiveness, put up a slide saying
it's still Perl.
Show that much of the basics still work:
my @x=('a' .. 'z'); @x[3,4]=qw(DeeDee Ramone);
say @x.splice(2,4).join(',')
c,DeeDee,Ramone,f
the splice and join as methods instead of subs is different in p6 then
p5 but should still look familiar. And if that is too harsh there's
use v5
so one can use the old syntax, if there's a want or need to.
The real benefit/amazing thing about perl6's back-compatibility is the
ability to still use the substantial mass of code libraries in cpan-
use Catalyst;
Huge plus there!
It's good to show/remind people that their investment in perl is still
valid when they pick up perl v6. That's one of the amazing things.
IMHO, it is really cool that the perl6 specs mandate that older perl
modules will work... just as I was happy that perl 5.0 let me use my
old perl 4 packages, with single quotes instead of :: and all...
I'd also like to help nip in the bud a tendency to view perl v6 as a
different language from perl v5. Along those lines, might be worth
mentioning how perl 6 is already leaking into perl 5.10+, things such
as say, the smart-match operator ~~, and various cpan modules that
implement perl v6 features like gather/take in perl v5.
Re: Amazing Perl 6
On Fri, May 29, 2009 at 10:47:44AM -0400, Buddha Buck wrote: : The questions which remain (for me, at least) is if (a) the symbols : survive in email, and (b) if they really are the proper marks for : Perl6. Yes, and yes. Me, I just defined a compose key, and compose does the right thing. (though I often use ^K in vim). Larry
Re: Amazing Perl 6
On Fri, May 29, 2009 at 09:50:36AM -0700, yary wrote:
: Back to the question of cool things about perl6- after showing some
: of the extended syntax and its expressiveness, put up a slide saying
: it's still Perl.
:
: Show that much of the basics still work:
: my @x=('a' .. 'z'); @x[3,4]=qw(DeeDee Ramone);
: say @x.splice(2,4).join(',')
: c,DeeDee,Ramone,f
That qw is not a good example of what still works, since it is supposed
to be interpreted as a qw subroutine (rakudo bug). I recommend square
brackets instead.
Larry
Re: Amazing Perl 6
John Macdonald john-at-perlwolf.com |Perl 6| wrote: On Thu, May 28, 2009 at 08:10:41PM -0500, John M. Dlugosz wrote: John Macdonald john-at-perlwolf.com |Perl 6| wrote: However, the assumption fails if process is supposed to mean that everyone is capable of generating Unicode in the messages that they are writing. I don't create non-English text often enough to have it yet be useful to learn how. (I'd just forget faster than I'd use it and have to learn it again each time - but Perl 6 might just be the tipping point to make learning Unicode composition worthwhile.) Just copy/paste from another message or a web page. Perhaps a web page designed for that purpose... Yep, I've done that. But comparing the difference in effort between: - press a key - Google for a web page that has the right character set, cut, refocus, paste means that I don't bother for the one or two weird characters every few months that is my current Unicode usage. If I were working with Unicode frequently, it would be worth setting up links and mechanisms, or learning the keyboard compose sequences for frequently used characters. I'm sure that there are many people in a similar situation. I noticed I Wikipedia that the edit page now has a selection at the bottom. Very handy. I usually use BabelMap to explore characters and also copy them to the clipboard. But a while back I started writing a book on basic science for kids and curious adults, and started off with scientific notation. The crosses, dots, and math-minus was driving my nuts, in such quantity as to prevent the flow of thought. So I bought a 16-button X-keys strip. Turns out the software stinks to high heaven and was essentially useless (hmm, what's the point, then?) so I had to write my own driver for it. Minimal, but gets the job done. --John
Re: Amazing Perl 6
On Fri, May 29, 2009 at 10:04:39AM -0700, Larry Wall wrote:
On Fri, May 29, 2009 at 09:50:36AM -0700, yary wrote:
: Show that much of the basics still work:
: my @x=('a' .. 'z'); @x[3,4]=qw(DeeDee Ramone);
: say @x.splice(2,4).join(',')
: c,DeeDee,Ramone,f
That qw is not a good example of what still works, since it is supposed
to be interpreted as a qw subroutine (rakudo bug). I recommend square
brackets instead.
And Rakudo now correctly treats qw() like a function instead of
a quote:
$ ./perl6
say qw(DeeDee Ramone);
Could not find non-existent sub Ramone
say qw (DeeDee Ramone);
DeeDeeRamone
say qw[DeeDee Ramone];
DeeDeeRamone
Thanks Larry!
Pm
Re: Amazing Perl 6
Buddha Buck blaisepascal-at-gmail.com |Perl 6| wrote: In response to this thread, I activated the US International keyboard layout, and once that's done theoretically one can get Spanish style quote mark with RightAlt+[ and RightAlt+] like so: « and ». The questions which remain (for me, at least) is if (a) the symbols survive in email, and (b) if they really are the proper marks for Perl6. Yes to both. I see them fine, and they are the U+00AB and U+00BB characters. Care to try ☃ ? That's alt-meta-hyper-doublebucky-cokebottle. --John
Re: Amazing Perl 6
Jon Lang dataweaver-at-gmail.com |Perl 6| wrote: On Fri, May 29, 2009 at 6:52 AM, John Macdonald j...@perlwolf.com wrote: Yep, I've done that. But comparing the difference in effort between: - press a key - Google for a web page that has the right character set, cut, refocus, paste means that I don't bother for the one or two weird characters every few months that is my current Unicode usage. If I were working with Unicode frequently, it would be worth setting up links and mechanisms, or learning the keyboard compose sequences for frequently used characters. I'm sure that there are many people in a similar situation. Agreed. Given the frequency with which « and » come up in Perl 6, I'd love to be able to have a simple keyboard shortcut that produces these two characters. Unfortunately, I am often stuck using a Windows system when coding; and the easiest method that I have available to me there (that I know of) is to pull up Character Map. Windows: see Tavultasoft's key mapper. Free to use existing keyboard layouts, pro version needed to make your own. It was awesome when writing stuff heavily-leaden with IPA characters.
Re: Amazing Perl 6
Buddha Buck blaisepascal-at-gmail.com |Perl 6| wrote: On Fri, May 29, 2009 at 3:43 PM, John M. Dlugosz 2nb81l...@sneakemail.com wrote: Buddha Buck blaisepascal-at-gmail.com |Perl 6| wrote: In response to this thread, I activated the US International keyboard layout, and once that's done theoretically one can get Spanish style quote mark with RightAlt+[ and RightAlt+] like so: « and ». The questions which remain (for me, at least) is if (a) the symbols survive in email, and (b) if they really are the proper marks for Perl6. Yes to both. I see them fine, and they are the U+00AB and U+00BB characters. Care to try ☃ ? That's alt-meta-hyper-doublebucky-cokebottle. That's an eth, ð, right? Hmm, doesn't look the same. What is that? --John Copy and paste it from the message into a word processor or other program that lets you choose a font where it is not missing and make it very large so you can see the details. Or see http://www.marco.org/83873337 for a large graphic in several fonts. --John
Re: Amazing Perl 6
On Fri, May 29, 2009 at 05:50:57PM -0500, John M. Dlugosz wrote:
Copy and paste it from the message into a word processor or other
program that lets you choose a font where it is not missing and make it
very large so you can see the details.
Or see http://www.marco.org/83873337 for a large graphic in several fonts.
Or feed it as an argument to this program, whereupon it will tell you
directly which character it is.
Larry
#!/usr/bin/perl -C
binmode STDOUT, :utf8;
$pat = @ARGV;
if (ord $pat 256) {
$pat = sprintf(%04x, ord $pat);
print That's $pat...\n;
$pat = '\b' . $pat . '\b';
}
elsif (ord $pat 128) {# arg in sneaky UTF-8
$pat = sprintf(%04x, unpack(U0U,$pat));
print That's $pat...\n;
$pat = '\b' . $pat . '\b';
}
@names = split /^/, do 'unicore/Name.pl';
for my $line (@names) {
$hex = hex($line);
$_ = chr($hex).\t.$line;
if (/$pat/io) {
print ' ' if /COMBINING/;
print;
}
}
Re: Amazing Perl 6
On Fri, 29 May 2009, Jon Lang wrote: On Fri, May 29, 2009 at 6:52 AM, John Macdonald j...@perlwolf.com wrote: Yep, I've done that. But comparing the difference in effort between: - press a key - Google for a web page that has the right character set, cut, refocus, paste means that I don't bother for the one or two weird characters every few months that is my current Unicode usage. If I were working with Unicode frequently, it would be worth setting up links and mechanisms, or learning the keyboard compose sequences for frequently used characters. I'm sure that there are many people in a similar situation. Agreed. Given the frequency with which « and » come up in Perl 6, I'd love to be able to have a simple keyboard shortcut that produces these two characters. Unfortunately, I am often stuck using a Windows system when coding; and the easiest method that I have available to me there (that I know of) is to pull up Character Map. There's some standard that says this is how to generate unicode: 1. Hold down Ctrl+Shift 2. Press U 3. Type the hexadecimal for the unicode character 4. Release Ctrl+Shift I'm under the impression that Windows supports this in some circumstances, and I know some Linux programs support it too. Unfortunately my e-mail program (Pine) seems to have some trouble with unicode -- I may have to look at alternatives after 14 years of use :(. HTH, - | Name: Tim Nelson | Because the Creator is,| | E-mail: wayl...@wayland.id.au| I am | - BEGIN GEEK CODE BLOCK Version 3.12 GCS d+++ s+: a- C++$ U+++$ P+++$ L+++ E- W+ N+ w--- V- PE(+) Y+++ PGP-+++ R(+) !tv b++ DI D G+ e++ h! y- -END GEEK CODE BLOCK-
Re: Amazing Perl 6
Ah yes, on the PC historically you hold down the ALT key and type the code with the numpad keys. There's some standard that says this is how to generate unicode: 1.Hold down Ctrl+Shift 2.Press U 3.Type the hexadecimal for the unicode character 4.Release Ctrl+Shift I'm under the impression that Windows supports this in some circumstances, and I know some Linux programs support it too. Unfortunately my e-mail program (Pine) seems to have some trouble with unicode -- I may have to look at alternatives after 14 years of use :(. HTH, - | Name: Tim Nelson | Because the Creator is,| | E-mail: wayl...@wayland.id.au| I am | - BEGIN GEEK CODE BLOCK Version 3.12 GCS d+++ s+: a- C++$ U+++$ P+++$ L+++ E- W+ N+ w--- V- PE(+) Y+++ PGP-+++ R(+) !tv b++ DI D G+ e++ h! y- -END GEEK CODE BLOCK-
Re: Amazing Perl 6
On Fri, 29 May 2009, John M. Dlugosz wrote: Ah yes, on the PC historically you hold down the ALT key and type the code with the numpad keys. At least when I used it, this was a decimal, rather than hex number, and had to be preceded by a 0 (zero). So if anyone is still on eg. Windows 98, this may be the way to go :). - | Name: Tim Nelson | Because the Creator is,| | E-mail: wayl...@wayland.id.au| I am | - BEGIN GEEK CODE BLOCK Version 3.12 GCS d+++ s+: a- C++$ U+++$ P+++$ L+++ E- W+ N+ w--- V- PE(+) Y+++ PGP-+++ R(+) !tv b++ DI D G+ e++ h! y- -END GEEK CODE BLOCK-
Re: Amazing Perl 6
Tim Nelson: There's some standard that says this is how to generate unicode: 1.Hold down Ctrl+Shift 2.Press U 3.Type the hexadecimal for the unicode character 4.Release Ctrl+Shift This works under GNOME, which also has a variant that is a little friendlier to the fingers (and probably also works better with various accessibility changes to the shift keys): 1. Press Ctrl+Shift+U 2. Release; see 'underlined u' feedback 3. Type the hex for the Unicode character (leading 0's optional); hex digits continue showing underline feedback 4. Press Enter; underlined u and digits are replaced with final glyph -'f
Re: Amazing Perl 6
Hi Damian, This is a really good list. Mind if I copy it / modify it and post it somewhere like my blog? One question: * Compactness of expression + semi-infinite data structures: @fib = 1,1...[+]# The entire Fibonacci sequence Very impressive. That's even shorter than Haskell. What's [+] ? How does this work? In Haskell: fibs = 1 : 1 : zipWith (+) fibs (tail fibs) PS: A really mean, but very effective, way of emphasizing the ease, expressiveness, compactness, and readability of Perl 6 code is to take each of the examples and show the same thing written in Java. ;-) It might be appropriate to compare some examples with Ruby or Python. Daniel.
Re: Amazing Perl 6
Daniel Carrera wrote: This is a really good list. Mind if I copy it / modify it and post it somewhere like my blog? That's fine. One question: * Compactness of expression + semi-infinite data structures: �...@fib = 1,1...[+] # The entire Fibonacci sequence Very impressive. That's even shorter than Haskell. What's [+] ? How does this work? The ... operator takes a list on the left and a generator sub (or block) on the right. It creates a lazy list consisting initially of the left operand. When the left operand runs out, the right operand is invoked to generate extra values. The generator grabs as many existing values from the end of the list as it needs arguments, then appends its result to the end of the lazy list. Lather, rinse, repeat, as often as necessary. In the Fibonacci example, the generator sub is [+], which is a shorthand for infix:+. So, after 1,1 the generator grabs the last two values (i.e. 1,1), adds them with infix:+, and puts 2 on the end of the list. Next time a value is needed, infix:+ grabs the final two list elements (now: 1,2), adds them, and appends 3 to the list. Et cetera, et cetera. For the use of ... to generate lists see: infix:..., the series operator under http://perlcabal.org/syn/S03.html#List_infix_precedence. For the [+] syntax, see http://perlcabal.org/syn/S03.html#Nesting_of_metaoperators PS: A really mean, but very effective, way of emphasizing the ease, expressiveness, compactness, and readability of Perl 6 code is to take each of the examples and show the same thing written in Java. ;-) It might be appropriate to compare some examples with Ruby or Python. Only if the comparisons are suitably invidious. ;-) Damian
Re: Amazing Perl 6
On Thu, May 28, 2009 at 1:37 AM, Daniel Carrera daniel.carr...@theingots.org wrote: Hi Damian, This is a really good list. Mind if I copy it / modify it and post it somewhere like my blog? One question: * Compactness of expression + semi-infinite data structures: �...@fib = 1,1...[+] # The entire Fibonacci sequence Very impressive. That's even shorter than Haskell. What's [+] ? How does this work? In Haskell: Start with the addition operator, '1 + 1'. Apply the reducing metaoperator to it so that it works syntactically like a function: '[+] 1, 1'. Instead of calling it, pass a code reference to it: '[+]'. The lazy list then uses that function to extend the list as needed. What I'm wondering is how the list knows to feed two items into '[+]'. While 'infix:+' must accept exactly two arguments, '[+]' can accept an arbitrarily long (or short) list of arguments. -- Jonathan Dataweaver Lang
Re: Amazing Perl 6
Jon Lang suggested: Start with the addition operator, '1 + 1'. Apply the reducing metaoperator to it so that it works syntactically like a function: '[+] 1, 1'. Instead of calling it, pass a code reference to it: '[+]'. No. [+] isn't the Code object for [+]; it's the Code object for infix:+. See http://perlcabal.org/syn/S03.html#Nesting_of_metaoperators What I'm wondering is how the list knows to feed two items into '[+]'. While 'infix:+' must accept exactly two arguments, '[+]' can accept an arbitrarily long (or short) list of arguments. And since [+] is infix:+, that's how it knows. :-) Damian
Re: Amazing Perl 6
So how is this: Any infix operator (except for non-associating operators) can be surrounded by square brackets in term position to create a list operator that reduces using that operation: reconciled with this: Any ordinary infix operator may be enclosed in square brackets with the same meaning ? And if [+] means infix:+, how do I refer to the Code of the list operator [+]?
Re: Amazing Perl 6
Mark J. Reed asked: So how is this: Any infix operator (except for non-associating operators) can be surrounded by square brackets in term position to create a list operator that reduces using that operation: reconciled with this: Any ordinary infix operator may be enclosed in square brackets with the same meaning The first refers to (meta)operators encountered where a term is expected; the second refers to operators encountered where an infix is expected (i.e. after a term). ? And if [+] means infix:+, how do I refer to the Code of the list operator [+]? prefix:[+] Damian
Re: Amazing Perl 6
Em Qui, 2009-05-28 às 21:36 +1000, Damian Conway escreveu: Mark J. Reed asked: ? And if [+] means infix:+, how do I refer to the Code of the list operator [+]? prefix:[+] Is that really? I mean... [ ] is a meta-operator, so [+] 1, 1, 2, 3 isn't a prefix, but a [ ] meta with + inside and the list as argument... daniel
Re: Amazing Perl 6
On Thu, May 28, 2009 at 8:43 AM, Daniel Ruoso dan...@ruoso.com wrote: Em Qui, 2009-05-28 às 21:36 +1000, Damian Conway escreveu: prefix:[+] Is that really? I mean... [ ] is a meta-operator, so [+] 1, 1, 2, 3 isn't a prefix, but a [ ] meta with + inside and the list as argument... The operator '[+]', which you get by applying the meta-operator '[...]' to the infix binary operator '+', is a prefix list operator. So that much makes sense. But I still think the two different meanings of square brackets in operators are going to confuse people. -- Mark J. Reed markjr...@gmail.com
Re: Amazing Perl 6
On Wed, May 27, 2009 at 05:42:58PM -0500, John M. Dlugosz wrote: Mark J. Reed markjreed-at-gmail.com |Perl 6| wrote: On Wed, May 27, 2009 at 6:05 PM, John M. Dlugosz 2nb81l...@sneakemail.com wrote: And APL calls it |¨ (two little dots high up) Mr. MacDonald just said upthread that the APL reduce metaoperator was spelled /. As in: +/1 2 3 6 So how does |¨ differ? Sorry, the two dots is APL's equivilent of the hyper operators, not the reduction operators. Easy to get those mixed up! For example, |1 2 3 ⍴¨ 10| would natively be written in Perl 6 as |10 »xx« (1,2,3)|. --John Yes. The full expression in raw APL for n! is: */in (where i is the Greek letter iota - iotan is Perl's 1..$n). Like many things in APL, having a 3-character combination of raw operators to provide a function makes creating a special operator unnecessary. (Although, if I recall correctly, there were also raw operators for combinatorial pick and choose, and factorial(n) is the same as choose(n,n) [or pick(n,n) whichever is the one the considers the order of the returned list to be significant] and factorial was actually returned if there was only one operand provided.)
Re: Amazing Perl 6
DC == Damian Conway dam...@conway.org writes:
DC * Grammars built into the language:
DC grammar Expr::Arithetic {
DC rule Expression { Mult ** $OP= + -}
DC rule Mult { Pow ** $OP= * / % }
DC rule Pow{ Term ** $OP= ^ }
DC token Term {
DC Literal
DC | '(' Expression ')'
DC }
DC token Literal { [+\-]? \d+ [ \. \d+ ]? }
DC }
DC * Grammar inheritance:
DC grammar Expr::Algebraic is Expr::Arithetic {
DC token Literal {
DC alpha+
DC | Expr::Arithetic::Literal
DC }
DC }
when i promote p6, the first and biggest thing i talk about
grammars. many of the other neat things (and damian listed a good bunch)
can be found in other langs or are nice but focused and small. p6
grammars are like nothing out there especially in any mainstream lang
today. and they are BIG in scope of what they can do. also they are very
accessible to newbies as they are based on the familiar regexes we all
use (and in almost all modern langs too). the mapping of grammar rules
to methods/subs and inheritance (which i generally despise but is
totally appropriate in grammars) is also amazing. now you can use
grammar libs and customize them as desired with little effort. before
this if you did have a grammar/parser (in any lang/system) you had to
learn its guts in detail before you dared to touch it. also grammars can
do dynamic things like build up a parsed data tree on the fly. you will
get what you expect (DWIM) with arrays of repeated grabbed sections
(properly nested as it follows your grammar). these are holy grails of
parsing and they come built in with incredible ease of use. note how
every other lang claims a perl5 compatible regex engine (and they lie as
none can do s///e among other things :). now with p6 they will never be
able to copy its grammars as it is a core part of p6 and not some regex
lib.
so you can talk about this amazing feature and be assured that the
audience will be amazed. :)
thanx,
uri
--
Uri Guttman -- u...@stemsystems.com http://www.sysarch.com --
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Re: Amazing Perl 6
On Thu, May 28, 2009 at 10:51:33AM -0400, John Macdonald wrote: : Yes. The full expression in raw APL for n! is: : : */in : : (where i is the Greek letter iota - iotan is Perl's 1..$n). Only if the origin is 1. This breaks under )ORIGIN 0. cough $[ /cough By the way, the assumption here is that everyone can process Unicode, so it's fine to write */⍳n. :) Note that that's the APL iota U+2373, not any of the other 30 or so iotas in Unicode. :/ Well, okay, half of those have precomposed accents, but still... Larry
Re: Amazing Perl 6
On Thu, May 28, 2009 at 09:43:58AM -0400, Mark J. Reed wrote: : So that much makes sense. But I still think the two different : meanings of square brackets in operators are going to confuse people. You're welcome to introduce more bracketing characters into ASCII. :P But seriously, this is one of those tagmemics things, where an A can be *used* as a B without actually being one. (For example, a noun can be used as a verb.) I think of [op] is the unambiguous name of an infix operator (bare op is of course useful when unambiguous), and [op] can be *used* as a prefix operator, or as the short name of the function when prefixed by the noun marker . Note that when you say func() you are, in fact, using the noun func as a verb. Anyway, I suspect people are generally pretty good at differentiating such things from the visual context. Larry
Re: Amazing Perl 6
On Thu, May 28, 2009 at 09:30:25AM -0700, Larry Wall wrote: On Thu, May 28, 2009 at 10:51:33AM -0400, John Macdonald wrote: : Yes. The full expression in raw APL for n! is: : : */in : : (where i is the Greek letter iota - iotan is Perl's 1..$n). Only if the origin is 1. This breaks under )ORIGIN 0. cough $[ /cough Yep. That was why I was comfortable playing with $[ when it first came along in early perl (wow, you can set the origin to any value, not just 0 or 1 - now that's progress). By the way, the assumption here is that everyone can process Unicode, so it's fine to write */⍳n. :) That's correct (in my case at least) if process means accept and display properly. However, the assumption fails if process is supposed to mean that everyone is capable of generating Unicode in the messages that they are writing. I don't create non-English text often enough to have it yet be useful to learn how. (I'd just forget faster than I'd use it and have to learn it again each time - but Perl 6 might just be the tipping point to make learning Unicode composition worthwhile.) Note that that's the APL iota U+2373, not any of the other 30 or so iotas in Unicode. :/ Well, okay, half of those have precomposed accents, but still... Larry
Re: Amazing Perl 6
Since when are we limited to ASCII again? :) If this is just a question of prefix vs infix telling you what [+] is shorthand for, OK. But it seems there's still scope for conflict between the two meanings of the square brackets. I mean, prefix ops can be used in reduce, too, right? Tagentially related: why doesn't simple + or + work for what we're currently spelling [+] (and which is more specifically spelled infix:+)? On 5/28/09, Larry Wall la...@wall.org wrote: On Thu, May 28, 2009 at 09:43:58AM -0400, Mark J. Reed wrote: : So that much makes sense. But I still think the two different : meanings of square brackets in operators are going to confuse people. You're welcome to introduce more bracketing characters into ASCII. :P But seriously, this is one of those tagmemics things, where an A can be *used* as a B without actually being one. (For example, a noun can be used as a verb.) I think of [op] is the unambiguous name of an infix operator (bare op is of course useful when unambiguous), and [op] can be *used* as a prefix operator, or as the short name of the function when prefixed by the noun marker . Note that when you say func() you are, in fact, using the noun func as a verb. Anyway, I suspect people are generally pretty good at differentiating such things from the visual context. Larry -- Sent from my mobile device Mark J. Reed markjr...@gmail.com
Re: Amazing Perl 6
On Thu, May 28, 2009 at 02:55:10PM -0400, Mark J. Reed wrote: : Since when are we limited to ASCII again? :) Well, we used some of Latin-1's bracket offerings, and people already carp about that. :) : If this is just a question of prefix vs infix telling you what [+] is : shorthand for, OK. But it seems there's still scope for conflict : between the two meanings of the square brackets. I mean, prefix ops : can be used in reduce, too, right? I will let you ponder the meaning of reduce a bit more, and the relationship of that to the respective arity of infixes vs prefixes. We already have hyper prefixes, if that's what you're thinking... : Tagentially related: why doesn't simple + or + work for what we're : currently spelling [+] (and which is more specifically spelled : infix:+)? Because it would conflict with twigils and such, not to mention alphabetic infixes. What would xx mean? Larry
Re: Amazing Perl 6
On Thu, May 28, 2009 at 02:55:10PM -0400, Mark J. Reed wrote: : Tagentially related: why doesn't simple + or + work for what we're : currently spelling [+] (and which is more specifically spelled : infix:+)? Oh, and why not +? Mainly because we have lots of infix operators containing and , but none containing [ and ], so we use [...] to disambiguate infixes already in things like [X]=. So reusing square brackets for [+] and [+] is deemed to be a good thing. But also because foo would mean ($/foo). [op] is a special form, so it can get away with parsing it's innards specially, whereas infix:op is not a special form, insofar as all adverbials are parsed similarly, and infix:['op'] therefore requires quotes, which is going the wrong direction when you're looking for a shortcut. People will get used to seeing [+] and thinking infix, whereas + would always be causing double-takes by its similarity to = and such. Larry
Re: Amazing Perl 6
On Thu, May 28, 2009 at 3:13 PM, Larry Wall la...@wall.org wrote: : I mean, prefix ops can be used in reduce, too, right? I will let you ponder the meaning of reduce a bit more, and the relationship of that to the respective arity of infixes vs prefixes. Well, infixes are necessarily binary, but while prefixes tend to be slurpy, I was thinking one could also declare a prefix op with a finite arity. And does [...] only reduce if what's inside is an operator? How do you do a reduce using a plain old binary subroutine? -- Mark J. Reed markjr...@gmail.com
Re: Amazing Perl 6
On Thu, May 28, 2009 at 03:33:34PM -0400, Mark J. Reed wrote: : On Thu, May 28, 2009 at 3:13 PM, Larry Wall la...@wall.org wrote: : : I mean, prefix ops can be used in reduce, too, right? : : I will let you ponder the meaning of reduce a bit more, and the : relationship of that to the respective arity of infixes vs prefixes. : : Well, infixes are necessarily binary, but while prefixes tend to be : slurpy, I was thinking one could also declare a prefix op with a : finite arity. Well, sure, but we de-emphasize that arity when parsing anyway for consistency. All listop-y operators parse infinite args, even if none of the candidates can handle them. And if the prefix is declared slurpy, you'd just call it directly on the arg list, I'd think, since it already has its own idea of reduction built in. : And does [...] only reduce if what's inside is an : operator? Yes, only operator, but including user-defined operators (unlike APL). : How do you do a reduce using a plain old binary subroutine? For the general form, [+] @x is equivalent to reduce [+], @x (Which is another good reason to keep the [+] form.) Note that the first arg to reduce is simply a noun, so forgetting the as in: reduce foo, @x would be an error. Unless foo returns something Callable, of course. But the user probably meant: reduce foo, @x. So just as turns the foo verb into a noun, it turns the [+] verb into a noun. Larry
Re: Amazing Perl 6
Daniel Ruoso asked: prefix:[+] Is that really? I mean... [ ] is a meta-operator, Sure. But once you []-meta an infix operator, you get a prefix operator. See http://perlcabal.org/syn/S03.html#Reduction_operators, which states: Any infix operator (except for non-associating operators) can be surrounded by square brackets in term position to create a list operator and has an example of actually implementing the prefix:[+] operator. Damian
Re: Amazing Perl 6
Mark J. Reed markjreed-at-gmail.com |Perl 6| wrote: So that much makes sense. But I still think the two different meanings of square brackets in operators are going to confuse people. I agree. The previously quoted passages in the synopses are confusing, too, since it doesn't make the context clear. If you find the shorthand too confusing, write it out as infix+ instead. Perl can do solid software engineering as well as one-liners. --John
Re: Amazing Perl 6
John Macdonald john-at-perlwolf.com |Perl 6| wrote: However, the assumption fails if process is supposed to mean that everyone is capable of generating Unicode in the messages that they are writing. I don't create non-English text often enough to have it yet be useful to learn how. (I'd just forget faster than I'd use it and have to learn it again each time - but Perl 6 might just be the tipping point to make learning Unicode composition worthwhile.) Just copy/paste from another message or a web page. Perhaps a web page designed for that purpose...
Re: Amazing Perl 6
On Thu, 28 May 2009, John M. Dlugosz wrote:
John Macdonald john-at-perlwolf.com |Perl 6| wrote:
However, the assumption fails if process is supposed to mean that
everyone is capable of generating Unicode in the messages that they
are writing. I don't create non-English text often enough to have
it yet be useful to learn how. (I'd just forget faster than I'd use
it and have to learn it again each time - but Perl 6 might just be
the tipping point to make learning Unicode composition worthwhile.)
Just copy/paste from another message or a web page. Perhaps a web page
designed for that purpose...
Or:
setxkbmap -device $kbd-{ID} 'us(intl),gr(basic),il(biblical)' \
-option grp:switch,grp:scroll_toggle,grp_led:scroll,lv3:ralt_switch
(Worksforme on Fedora 10)
Where the -device option chooses a keyboard (defaults to the core
keyboard); if you need the number, use xinput list.
That will let you type in English, Greek, and Hebrew, with lots of
funny symbols accessible by pressing the right alt key, and using the scroll
lock key to switch groups.
Oh, actually, I thing the scroll lock stuff only works on my computer.
But I'm sure you get the idea :).
And the APL keyboard layout will appear in xorg soon, as soon as
the xkeybaord-config exotic layouts issue is closed.
HTH,
-
| Name: Tim Nelson | Because the Creator is,|
| E-mail: wayl...@wayland.id.au| I am |
-
BEGIN GEEK CODE BLOCK
Version 3.12
GCS d+++ s+: a- C++$ U+++$ P+++$ L+++ E- W+ N+ w--- V-
PE(+) Y+++ PGP-+++ R(+) !tv b++ DI D G+ e++ h! y-
-END GEEK CODE BLOCK-
Re: Amazing Perl 6
On Thu, May 28, 2009 at 08:06:14PM -0500, John M. Dlugosz wrote: Mark J. Reed markjreed-at-gmail.com |Perl 6| wrote: So that much makes sense. But I still think the two different meanings of square brackets in operators are going to confuse people. I agree. The previously quoted passages in the synopses are confusing, too, since it doesn't make the context clear. If you find the shorthand too confusing, write it out as infix+ instead. Perl can do solid software engineering as well as one-liners. Which, of course, is not as solid as you think, since you left out the : of the adverbial there... :) So let's not make the mistake of thinking something longer is always less confusing or more official. Larry
Amazing Perl 6
Hi, As I recently mentioned in IRC, I'm going to give a talk about Perl 6 in the International Free Software Forum in Porto Alegre, Brazil. For those who don't know FISL, it's one of the biggest events in the world with ~ 5k people attending (http://www.fisl.org.br). This talk is not targetted only to Perl people, but to the general public of the event (which is one of the most diverse events I ever participated). Of course it's on the Development/Perl track, but it should get a lot of non-Perl people as well. I'm planning to do a presentation to highlight the most impressive aspects to Perl 6, in some way explaining why we are working on it for 9 years while still being excited about it. So, as illustrations to my presentation, I'd like to show code snippets in the slides, which comes to the subject of this mail. Please post impressive Perl 6 code snippets, we all know there are several, and I really would like to give people some idea of why Perl 6 is so cool. I started a page in the Perl 6 wiki for that: http://www.perlfoundation.org/perl6/index.cgi?amazing_perl_6 daniel
Re: Amazing Perl 6
Hi Daniel,
Sounds very interesting. Can you post slides? It'd be cool if the talk
was taped, like the Google tech talks. Will it be in English? I don't
speak Portuguese (I do speak Spanish and some German).
I'm planning to do a presentation to highlight the most impressive
aspects to Perl 6, in some way explaining why we are working on it for 9
years while still being excited about it.
Note: By trying to get things that are impressive, you don't want to do
things that are so complicated that the audience gets the feeling that
Perl 6 is too hard.
That said, lazy lists like 0..Inf is something that is both impressive
and easy to understand.
You could try to think of things that are made easier or simpler by the
new Perl 6. The only examples I can think of right now are:
sub foo($x,$y) { ... }
if $a $b $c { .. }
for @people - $dude { do something }
for %people.kv - $key, $value { do something }
Back on the subject of impressive, I really like lambdas:
$code = - $x { say $x }
$code(hello world);
I know this is not the approach you had in mind, but what do you think?
Daniel.
Re: Amazing Perl 6
Em Qua, 2009-05-27 às 18:46 +0200, Daniel Carrera escreveu: Hi Daniel, Hi Daniel, :P Sounds very interesting. Can you post slides? It'd be cool if the talk was taped, like the Google tech talks. Will it be in English? I don't speak Portuguese (I do speak Spanish and some German). It will be taped, as every talk in FISL is... The talk will be in portuguese, as the audience of the forum is moslty portuguese speaker, and submitting it in english would require being in the main auditorium (the one with simultaneous translation) and getting that approved would be harder... But I guess subtitles can be made later... I'm planning to do a presentation to highlight the most impressive aspects to Perl 6, in some way explaining why we are working on it for 9 years while still being excited about it. Note: By trying to get things that are impressive, you don't want to do things that are so complicated that the audience gets the feeling that Perl 6 is too hard. That's a thin line, but I'm aware of it... I know this is not the approach you had in mind, but what do you think? Well, you really made me realize that I'm looking for things that make me impressed, and probably I don't get impressed that easy nowadays ;) daniel
Re: Amazing Perl 6
Well, you really made me realize that I'm looking for things that make me impressed, and probably I don't get impressed that easy nowadays ;) Well, maybe you should relax your expectations. People who haven't been following P6 development for the last near-decade may be impressed by stuff that seems trivial to veterans. :) I really like the factorial example on the wiki page. That really gets across the expressiveness of P6, without being too hard to understand despite its brevity. It's not often you find an elegant yet non-recursive solution to that problem. I do think captures are inherently impressive, but not easy to explain...
Re: Amazing Perl 6
Daniel Ruoso wrote:
I know this is not the approach you had in mind, but what do you think?
Well, you really made me realize that I'm looking for things that make
me impressed, and probably I don't get impressed that easy nowadays ;)
I understand. Your experience with Perl 6 makes you harder to impress.
So you are probably not impressed by the fact that you can do this:
if $a $b $c { ... }
But what if I told you that my university professor (while I was in
university) chose to teach in Python because he saw that in Python you
could do if a b c: and he thought oh! that's so cool!.
You know what you might want to do? Start with simple but neat examples
that everyone can understand (such as the if statement) and work upward
to more complex examples, so that your last example is something really
impressive. I figure that if you work up to it gradually, the audience
will not be intimidated when they see a large powerful example.
Daniel.
Re: Amazing Perl 6
Mark J. Reed wrote:
I really like the factorial example on the wiki page. That really
gets across the expressiveness of P6, without being too hard to
understand despite its brevity.
sub postfix:! { [*] 1..$^n }
say 5!;
WOW!! That *IS* cool. Can you explain to me how it works? I figured out
postfix: myself, but the rest is obscure to me.
I do think captures are inherently impressive, but not easy to explain...
Got a link?
Daniel.
Re: Amazing Perl 6
On Wed, May 27, 2009 at 1:42 PM, Daniel Carrera
daniel.carr...@theingots.org wrote:
sub postfix:! { [*] 1..$^n }
say 5!;
WOW!! That *IS* cool. Can you explain to me how it works? I figured out
postfix: myself, but the rest is obscure to me.
Key concepts:
1. placeholder variables. The ^ in $^n means it's a placeholder: no
predeclaration required, and placeholders in an expression are
assigned the passed-in arguments in serial order. (The sub could also
have been written more traditionally as sub postfix:!($n) { [*]
1..$n } .)
2. the range operator .. : $x..$y for integers $x and $y generates,
in list context, a list of the integers from $x to $y, inclusive.
3. the reduction meta-operator [...] : [OP](@list) collects the
result of applying OP to the elements of the list in order. That is,
assuming foo() is a binary sub, [foo](1,2,3,4) =
foo(foo(foo(1,2),3),4). So [+](@list) generates a sum of the listed
values, [*] generates their product, etc.
So, given the argument to !:
1. create a list of integers from 1 to that value (1..$^n)
2. multiply them all together ([*])
and of course a sub without an explicit return statement returns the
value of the last expression.
I do think captures are inherently impressive, but not easy to explain...
Got a link?
Daniel.
--
Mark J. Reed markjr...@gmail.com
Re: Amazing Perl 6
Daniel Carrera wrote:
sub postfix:! { [*] 1..$^n }
say 5!;
WOW!! That *IS* cool. Can you explain to me how it works? I figured out
postfix: myself, but the rest is obscure to me.
Here is another idea: Is it possible to declare a circumfix function
that calculates the magnitude of a vector?
$magnitude = |@vector|;
You know how in math, two vertical bars are a standard notation for
magnitude. Oh oh oh... is it possible to define a circumfix function for
the dot product? Something like:
$dot_product = @vector1,@vector2;
Is that possible? That would be uber-cool.
Daniel.
Re: Amazing Perl 6
Mark J. Reed wrote: 3. the reduction meta-operator [...] : [OP](@list) collects the result of applying OP to the elements of the list in order. That is, assuming foo() is a binary sub, [foo](1,2,3,4) = foo(foo(foo(1,2),3),4). So [+](@list) generates a sum of the listed values, [*] generates their product, etc. Wow... That's a foldl! In a functional language, that would be called a fold. It's very popular in Haskell. I like that Perl 6 seems to be taking steps in the direction of functional languages. First lazy lists (0..Inf) and now a fold. :-D Daniel.
Re: Amazing Perl 6
Note that of the examples given, only Perl 6 and Common Lisp do two things
that help immensely simplify the result:
1. reference the built-in * operator directly, without having to wrap it in
a lambda expression;
2. actually name the function !
The Lisp version suffers from the lack of a built-in range constructor.
On Wed, May 27, 2009 at 2:21 PM, Mark J. Reed markjr...@gmail.com wrote:
In Haskell it may be called fold (well, foldl and foldr), but the concept
has has a variety of names. Two of the more common ones are reduce and
inject; I believe Perl6 chose reduce for consistency with the Perl5
List::Util module. Common Lisp and Python also call it reduce:
(defun ! (n)
(reduce #'* (loop for i from 1 to n collecting i)))
def fact(n):
return reduce(lambda x,y: x*y, range(1,n+1))
While Ruby calls it inject.
def fact(n)
(1..n).inject { |x,y| x*y }
end
Perl 6 has a lot of functional features. IMO the nice thing about its
version of reduce is the way it's incorporated into the syntax as a
metaoperator.
--
Mark J. Reed markjr...@gmail.com
--
Mark J. Reed markjr...@gmail.com
Re: Amazing Perl 6
On Wed, May 27, 2009 at 02:21:40PM -0400, Mark J. Reed wrote:
On Wed, May 27, 2009 at 1:59 PM, Daniel Carrera
daniel.carr...@theingots.org wrote:
Wow... That's a foldl! In a functional language, that would be called a
fold.
In Haskell it may be called fold (well, foldl and foldr), but the concept
has has a variety of names. Two of the more common ones are reduce and
inject; I believe Perl6 chose reduce for consistency with the Perl5
List::Util module. Common Lisp and Python also call it reduce:
(defun ! (n)
(reduce #'* (loop for i from 1 to n collecting i)))
def fact(n):
return reduce(lambda x,y: x*y, range(1,n+1))
While Ruby calls it inject.
def fact(n)
(1..n).inject { |x,y| x*y }
end
Perl 6 has a lot of functional features. IMO the nice thing about its
version of reduce is the way it's incorporated into the syntax as a
metaoperator.
Historically, the name reduce was used (first?) in APL, which also
provided it as a meta-operator. op/ would use op to reduce the array
on the right of the meta-operator. (Although, in APL, it could be an
n-dimensional object, not necessarily a 2-dimensional array - the
reduce would compute an (n-1)-dimensional object from it. This could
be used to generate row-sums and column sums. APL was extremely terse,
you could compute almost anything in a single line - Perl golfing
afficionados have never really caught up, although with the addition
of Unicode operators Perl 6 could now go ahead.)
Re: Amazing Perl 6
Daniel Ruoso daniel-at-ruoso.com |Perl 6| wrote: Please post impressive Perl 6 code snippets, we all know there are several, and I really would like to give people some idea of why Perl 6 is so cool. Of late, new languages have been created that are going backwards. That is, they are regressing to a more primitive form. C# is just Java with a different syntax. Java is for people who can't handle the complexities of C++. begin barbe voice Multiple inheritance is hard!/end. So don't provide multiple inheritance, just rip it out, without replacing it with ANY other way to reuse implementation, so everyone uses copy/paste to build concrete classes that should have common code with others. But... language science and research did not stop after OO was introduced. Why don't new language use new, better ways of doing things? Well, Perl 6 does. That's what's cool about it, for me: it looks toward newer ideas on a deep level, not just some shallow change but otherwise the same old stuff. Look at Roles to showcase that. Also, there is full delegation of methods with a terse syntax, useful for aggregating things that provide a desired interface. And hopefully it will realize more of the ramifications behind allowing generic types, as my own research (see http://www.dlugosz.com/Perl6/web/isa-inheritance.html suggests. It will embrace multi-core computers with implicit threading constructs. It's not just cool because its new features -- they are fundamental ideas that should have been with us for some time, but other languages refuse to accept. --John
Re: Amazing Perl 6
On May 27, 2009 01:52:58 pm Mark J. Reed wrote:
On Wed, May 27, 2009 at 1:42 PM, Daniel Carrera
daniel.carr...@theingots.org wrote:
sub postfix:! { [*] 1..$^n }
say 5!;
WOW!! That *IS* cool. Can you explain to me how it works? I figured out
postfix: myself, but the rest is obscure to me.
Key concepts:
1. placeholder variables. The ^ in $^n means it's a placeholder: no
predeclaration required, and placeholders in an expression are
assigned the passed-in arguments in serial order. (The sub could also
have been written more traditionally as sub postfix:!($n) { [*]
1..$n } .)
2. the range operator .. : $x..$y for integers $x and $y generates,
in list context, a list of the integers from $x to $y, inclusive.
3. the reduction meta-operator [...] : [OP](@list) collects the
result of applying OP to the elements of the list in order. That is,
assuming foo() is a binary sub, [foo](1,2,3,4) =
foo(foo(foo(1,2),3),4). So [+](@list) generates a sum of the listed
values, [*] generates their product, etc.
So, given the argument to !:
It might have been implied, but you kind of missed the discussion about the
ability to add new operators (and how they relate to other operators).
To recap (slightly differently) there are several impressive features that are
easier to explain and can be part of the build up to the factorial example:
Placeholder variables: non-declared and descriptive
Ranger operators: not so impressive and inherited from perl5 (etc.)
The reduction meta-operator [...]: nice syntax and no need to provide a
identity/seed element
A side discussion of other interesting meta-operators
User defined operators: overloading and novel mechanism of declaring
precedence (looser, tighter, etc.)
Finally, a simple slide where the factorial definition takes up the whole slide
and let the audience have a few moments of silence to let them figure it out
and to start to really appreciate the expressiveness/impressiveness of perl6
Henry
1. create a list of integers from 1 to that value (1..$^n)
2. multiply them all together ([*])
and of course a sub without an explicit return statement returns the
value of the last expression.
I do think captures are inherently impressive, but not easy to
explain...
Got a link?
Daniel.
--
Henry Baragar
Instantiated Software
416-907-8454 x42
Re: Amazing Perl 6
Mark J. Reed wrote: In Haskell it may be called fold (well, foldl and foldr), but the concept has has a variety of names. Two of the more common ones are reduce and inject; The terms I've seen are fold and reduce. The fold term is not just from Haskell. I've seen it elsewhere. If you had said inject I wouldn't have known what you meant. Daniel.
Re: Amazing Perl 6
Mark J. Reed wrote: Note that of the examples given, only Perl 6 and Common Lisp do two things that help immensely simplify the result: 1. reference the built-in * operator directly, without having to wrap it in a lambda expression; 2. actually name the function ! Yes, very neat. Haskell does that too, but I don't know if you can make the function a postfix in Haskell. Daniel.
Re: Amazing Perl 6
On Wed, May 27, 2009 at 3:38 PM, Daniel Carrera daniel.carr...@theingots.org wrote: The terms I've seen are fold and reduce. The fold term is not just from Haskell. I've seen it elsewhere. If you had said inject I wouldn't have known what you meant. The name inject comes from Smalltalk, where you :inject the initial value :into the operation, whose arguments are the accumulator and the new item (it has no fold-1 variant). Wikipedia mentions accumulate (C++) and compress (no example cited) as additional names. In Perl6, I assume [...] automatically folds left on left-associative operators and right on right-associative ones? -- Mark J. Reed markjr...@gmail.com
Re: Amazing Perl 6
On Wed, May 27, 2009 at 07:56:42PM +0200, Daniel Carrera wrote: Here is another idea: Is it possible to declare a circumfix function that calculates the magnitude of a vector? $magnitude = |@vector|; You know how in math, two vertical bars are a standard notation for magnitude. Oh oh oh... is it possible to define a circumfix function for the dot product? Something like: $dot_product = @vector1,@vector2; Is that possible? That would be uber-cool. The problem with that is the presence of an existing prefix:| operator. One could fake it with a postfix:| macro that rewrites the AST produces by the prefix, except no one implements macros yet. But circumfix openers have to share longest-token space with prefixes. You could maybe use broken bar instead, circumfix:¦ ¦. Larry
Re: Amazing Perl 6
Sorry, only answered half of your question.
On Wed, May 27, 2009 at 07:56:42PM +0200, Daniel Carrera wrote:
Oh oh oh... is it possible to define a circumfix function for
the dot product? Something like:
$dot_product = @vector1,@vector2;
Is that possible? That would be uber-cool.
More likely just use
sub infix:· (@a,@b) { ... }
$dot_product = @vector1 · @vector2;
Or some such.
Larry
Re: Amazing Perl 6
Larry Wall wrote:
$dot_product = @vector1,@vector2;
Is that possible? That would be uber-cool.
More likely just use
sub infix:· (@a,@b) { ... }
$dot_product = @vector1 · @vector2;
Thanks.
And for Daniel R. and other observers, how about this:
# Courtesy of Larry
sub infix:· (@a,@b) { [+] @a »*« @b }
my @vector1 = (1,2,3);
my @vector2 = (2,3,4);
say @vector1 · @vector2;
I think that's really nifty. So you can talk about Hyper operators and
then show the dot product. What do you think?
Daniel.
Re: Amazing Perl 6
Mark J. Reed markjreed-at-gmail.com |Perl 6| wrote: Well, you really made me realize that I'm looking for things that make me impressed, and probably I don't get impressed that easy nowadays ;) Well, maybe you should relax your expectations. People who haven't been following P6 development for the last near-decade may be impressed by stuff that seems trivial to veterans. :) I really like the factorial example on the wiki page. That really gets across the expressiveness of P6, without being too hard to understand despite its brevity. It's not often you find an elegant yet non-recursive solution to that problem. I do think captures are inherently impressive, but not easy to explain... captures are inherently impressive, but not easy to explain... Since nobody's done so yet, I suppose so. As for fun and expressive, have you seen my APL and Lisp inspired stuff? In the latter, I found out for myself just how expressive it is in a deep appreciation I didn't have before. In particular, why is the Perl 6 version even shorter than Lisp? Because it has the fully overarching self-descriptive features, but lets you leave out excess verbage.
Re: Amazing Perl 6
Mark J. Reed markjreed-at-gmail.com |Perl 6| wrote:
In Haskell it may be called fold (well, foldl and foldr), but the concept
has has a variety of names. Two of the more common ones are reduce and
inject; I believe Perl6 chose reduce for consistency with the Perl5
List::Util module. Common Lisp and Python also call it reduce:
(defun ! (n)
(reduce #'* (loop for i from 1 to n collecting i)))
def fact(n):
return reduce(lambda x,y: x*y, range(1,n+1))
While Ruby calls it inject.
def fact(n)
(1..n).inject { |x,y| x*y }
end
And APL calls it |¨ (two little dots high up)
|
Re: Amazing Perl 6
Mark J. Reed markjreed-at-gmail.com |Perl 6| wrote: On Wed, May 27, 2009 at 6:05 PM, John M. Dlugosz 2nb81l...@sneakemail.com wrote: And APL calls it |¨ (two little dots high up) Mr. MacDonald just said upthread that the APL reduce metaoperator was spelled /. As in: +/1 2 3 6 So how does |¨ differ? Sorry, the two dots is APL's equivilent of the hyper operators, not the reduction operators. Easy to get those mixed up! For example, |1 2 3 ⍴¨ 10| would natively be written in Perl 6 as |10 »xx« (1,2,3)|. --John
Re: Amazing Perl 6
Here are a few of my favourite Perl 6 selling points:
* Compactness of expression:
say 'Hello, World!';
* Compactness of expression + semi-infinite data structures:
@fib = 1,1...[+]# The entire Fibonacci sequence
* Junctions make comparisons much more natural:
if $dice_sum == 7 | 11 {
say 'Natural!'
}
elsif $dice_sum == 2 | 3 | 12 {
say 'Craps!'
}
* Given/when takes that even further:
given $dice_sum {
when 7 | 11 { say 'Natural!' }
when 2 | 3 | 12 { say 'Craps!' }
}
* Junctions + n-ary comparison help too:
if 0 all(@coefficients) = 1 {
say 'Coefficients are already normalized.';
}
* Junctive comparisons + the max operator:
if any(@new_values) all(@existing_values) {
$upper_limit = [max] @new_values;
}
* .invert and .push makes hashes (especially hoa's) vastly more useful
(and .perl makes debugging vastly easier):
my %comments =
perl6 = Amazing Revolutionary,
perl5 = Essential Amazing,
perl4 = Classic,
perl1 = Classic;
my %epithets;
%epithets.push(%comments.invert);
say %comments.perl;
say %epithets.perl;
* Unicode source and data overthrows US cultural hegemony!
(oh, and Hinrik has the coolest name in the entire Perl community :-)
my @recepción;
my $Gruß = 'olá'
my $óvoµa = 'Hinrik Örn Sigurðsson';
push @recepción, $Gruß, $óvoµa!;
* Unary method call + topicalization simplifies multiple operations
on objects:
for @parcels {
.address;
.weigh;
.ship;
while .shipping {
.fold;
.spindle;
.mutilate;
}
.deliver;
}
* Subtypes make typing far more precise (and hence more useful):
my $filename of Str where /\w**8 '.' \w**3/;
my $octet of Int where { 0 = $^value = 255 }
* Command-line parsing using standard language features:
sub MAIN ($text, Bool :f($foo), Str :B($bar), *...@files)
{
...
}
# Can then be invoked as:
my_prog.p6 -f -Bbaz 'two words' file1 file2 etc
* Grammars built into the language:
grammar Expr::Arithetic {
rule Expression { Mult ** $OP= + -}
rule Mult { Pow ** $OP= * / % }
rule Pow{ Term ** $OP= ^ }
token Term {
Literal
| '(' Expression ')'
}
token Literal { [+\-]? \d+ [ \. \d+ ]? }
}
* Grammar inheritance:
grammar Expr::Algebraic is Expr::Arithetic {
token Literal {
alpha+
| Expr::Arithetic::Literal
}
}
* Only perl can parse Perl 5 but Even Perl 6 can parse Perl 6:
given $source_code {
$parsetree = m:keepall/Perl::prog/;
}
And that's without even mentioning all the new OO features, multiple
dispatch, roles, delegation, macros, etc., etc. The problem with demo-
ing the awesomeness of Perl 6 is always running out of demo time before
running out of demo-able awesomeness.
Damian
PS: A really mean, but very effective, way of emphasizing the ease,
expressiveness, compactness, and readability of Perl 6 code is to
take each of the examples and show the same thing written in
Java. ;-)
Re: Amazing Perl 6
On Wed, May 27, 2009 at 2:39 PM, John Macdonald j...@perlwolf.com wrote:
Historically, the name reduce was used (first?) in APL, which also
provided it as a meta-operator. op/ would use op to reduce the array
on the right of the meta-operator.
It's quite possible that APL was the first use of the term reduce in
that sense - I know that (reduce) didn't make it into LISP until
relatively late, possibly not until Common Lisp.
APL was extremely terse, you could compute almost anything in a single line
- Perl golfing
afficionados have never really caught up, although with the addition
of Unicode operators Perl 6 could now go ahead.)
Perhaps Perl 6 should not aspire to the expressiveness of APL. :) As
nice as it is that you can write Conway's Life in a one-liner(*), I
think that a little verbosity now and then is a good thing for
legibility
--
Mark J. Reed markjr...@gmail.com
(*) life ←{↑1 ω⌵.^3 4=+/,‾1 0 1◦.ϕ⊂ω}
I haven't tested it, but the above will allegedly compute the next
generation from a Life configuration (input and output represented as
a matrix of 1s and 0s).
