Re: Arglist I/O [Was: Angle quotes and pointy brackets]
On Fri, 3 Dec 2004, Larry Wall wrote:
On Fri, Dec 03, 2004 at 06:43:05PM +, Herbert Snorrason wrote:
: This whole issue kind of makes me go 'ugh'. One of the things I like
: best about Perl is the amazing simplicity of the input construct.
Hmm.
while () {...}
for .lines {...}
Looks like a wash to me.
Partly it does. The point is that not only the is simple, but that it
is also visually distinctive, which is important IMHO.
Obviously the new proposal of unary C= is just as good from this point
of view...
: Replacing that with something that not only is object oriented, but on
: top of that also LOOKS object oriented is bound to be a loss. It's
: going to be that bit longer to write, and not the least bit easier to
: understand.
Really? I dare you to show those two lines to any random
computer-literate but non-Perl-speaking stranger and see which one
they understand better.
Of course they'd understand better the latter, but I think that there's a
limit to non-Perl-speaking-people-friendship. After all this may be useful
for learning perl, but learning it to a good degree would always involve
getting acquainted with quite a lot of typical idioms, so this does not
make much of a point IMHO, provided that when a typical user becomes
familiar with those idioms he can perceive (i) how good they look in
source code (ii) how useful they result in practice.
It's all cargo cult at that level anyway, so whether it looks OO or not
is really completely immaterial to its usability.
Indeed it's not *purely* a matter of looking OO, but of looking yet
another more-or-less alphabetic string (yes, even with a prepended point:
it's just not as markedly distinctive!). As I said, is deeply etched in
Perl programmers' cortex as an input operator. In other words it may well
be cargo cult, but not in a totally negative acceptation: I mean... till
it works, and works well as it currently does!
And I don't buy the nuclear blackmail argument either. I'll start
worrying about people switching to Python and Ruby when those languages
get a clue about how natural languages work. As far as I know, there's
OTOH, as a side note, but not a totally unrelated one, I guess, one should
pay some attention not to exaggerate following natural languages
principles in designing programming languages: granted, I appreciate their
pervasiveness in (current) perl and indeed probably this is one of the
reasons I love it. But I think that there are some natural limits to this
as well: AFAIK any attempt to overcome them was basically a failure. We
want the *right* mixture of conciseness, intutivity, clarity instead. In
this sense a construct like
while () {
...
}
really doesn't resamble any natural language construct as far as I can
see, but indeed it's an idiom that perl programmers easily become familiar
with and like to use... well, I think so!
Michele
--
I hold a square measuring 10x10 metres away from a person who is standing
100 metres away.
I ask them to shoot the square with a high-accuracy gun.
Don't stand there holding the square when they are shooting...
- Robert Israel in sci.math, Re: Scaling
Re: Topification [Was: Arglist I/O [Was: Angle quotes and pointy brackets]]
Austin Hastings wrote:
I'll guess that you're pointing at
.:send_one($_);
Which supposedly uses topic to resolve .:send_one into $this.send_one.
If that works, then I'm happy -- I like being able to control topic and
$_ differently. But if Cfor changes topic, then what?
OUTER::.:send_one($_);
Yuck.
I believe it needs to be
method send ($self: [EMAIL PROTECTED]) {
$self.:send_one(BEGIN);
for @data {
$self.:send_one($_);
}
$self.:send_one(END);
}
While that works (I think it works anyway), its debatable if it's nice
or not. The first and last calls to .:send_one shouldn't need the $self,
but I put it there because if you use the $self inside the for in a
method that short, it's nice and clear to have it outside it as well.
I suspect the original example expands the for loop into the equivalent of:
for @data - $item {
$item.:send_one($item);
}
And it doesn't take a $larry to figure out that this isn't going to make
the compiler very happy, as it's most likely a violation of class access
control, I would have thought.
So Luke, am I right?
Re: pull put (Was: Angle quotes and pointy brackets)
On Mon, 06 Dec 2004 12:22:22 GMT, Smylers [EMAIL PROTECTED] wrote: David Green writes: I guess we could always use prepend/append, pull/pop. No! Cpush and Cpop are a well-defined pair, not just in Perl, for dealing with stacks; we should keep those as they are. (And no synonyms, before somebody suggests any!) Yeah. Cpush and Cpop are old and glorious ones (asm comes to mind), and Cshift is too (even DOS .bat files used it, AFAIR), and it's a one of the most used perl5 CORE:: ops (it's more common than other three) .. And I like to shift :) the only doubtful word for me is unshift. Althought I would be pretty happy if we leave it as is, Cput is nice and short. but please don't swap meanings of old ops! if old push suddenly would try to unshift something, it could bring some perl5 programmers to hospital.
Re: iteration (was Re: Angle quotes and pointy brackets)
In article [EMAIL PROTECTED], [EMAIL PROTECTED] (Matt Diephouse) wrote: On Sat, 04 Dec 2004 08:59:24 -0700, David Green [EMAIL PROTECTED] wrote: Cdoes Iterate signifies a role named Iterate. Roles are sort of a mix of interfaces and mixins (as I understand it -- I'm still waiting for E12). So saying a class fulfills a role just means that it provides certain methods. In this case, I was saying class with the Iterate role would provide a C.next method. I thought of that at first, but I don't want to have to call my iterating method next any more than I want to *have* to call my constructor new. But there is a difference in that new is called by some user who is supposed to have read the documentation, whereas next needs to get implicitly called by for. So maybe it really should be a Role. (One can always provide methods with better names that simply call the real .next, .prev, .final, etc. for increased user-friendliness.) eof := final;# is that how to create an alias for a sub/method? We've got while for looping, .next for iterating, and for for doing both in one convenient little shortcut. But for needs to know if it has an iterator or a list. You don't want it iterating over things you didn't want it iterating. In this case, I was suggesting making an, though I suppose something like C$sth.execute could just return one. Well, I was looking at lists as being kinds of iterators. If you want to for over an iterator without actually iterating it, I guess you'd have to make a reference to it or put it inside a list (so the list would be iterated instead). - David iterate: to go around and around, like my head Green
Re: pull put (Was: Angle quotes and pointy brackets)
In article [EMAIL PROTECTED], [EMAIL PROTECTED] (Luke Palmer) wrote: But what we'd really like to do is: given the user knows what push/pop do, what would they *guess* to mean shift (I tend to think that this is a very good technique for naming). And, well, I'm thinking pull. So it's a toss-up between shift/unshift and put/pull. I think push and pull fairly naturally could be taken to refer to the front of an array; you might even argue that the natural direction for something to pop is away from you (i.e. off the back) The problem I have with push/pull referring to opposite ends is that the same person is doing the pushing and the pulling, so both words ought to apply to the same end of the array (the front end), which violates the comp-sci-y expectations. (And although normally I'm happy to chuck CS jargon out the window, because so much of it is really bad, the push/pop thing goes pretty deep.) Not to mention everyone coming from Perl 6. Though if we had push without pop, that wouldn't be as bad. I guess we could always use prepend/append, pull/pop. You might not guess what they meant, but once you know, I think the meanings are reasonably obvious. (Dislike typing though I may, I'm hesitant to suggest prep and app.) Hm, actually counting letters, prepend is no longer than unshift (and if not a real word, is at least used as one more often than unshift is). In fact, prepend/append/pull/pop altogether are only one letter more than push/pop/shift/unshift. So those are now officially my preferred replacements. But if we want something that makes it immediately obvious what end of the array we're messing with.. something visually obvious... ooh, this sounds like a job for Unicode!! (Just kidding. Sort of.) We've already got those lovely pipe operators to build on, and they can already do assignment; if you can go from = to +=, why not from == to +==? @a == $foo, $bar; # @a=($foo, $bar) $foo, $bar == @a; # ditto @a +== $foo, $bar; # push @a, $foo, $bar $foo, $bar ==+ @a; # unshift @a, $foo, $bar @a -== $foo, $bar; # ($bar, $foo) = (pop @a, pop @a) $foo, $bar ==- @a; # ($foo, $bar) = (shift @a, shift @a) The + or - tells you whether you're adding on or taking away, and the arrow points to (or from) the end of the array you're doing it to. (I know some people will hate four symbols in a row. That's why we have seven-letter alternatives like prepend.) I was going to say an advantage over old-fashioned pop/shift is that you could remove more than one element at a time, but there isn't any reason for their P6 versions not to return as many items as are want()ed, is there? The bad news (assuming anyone actually thinks there's anything good in the above suggestion) is that since +== and friends are assignment operators, you can't just do foobar( @a-==, $x, $y). Um, unless -== could be made to work as a unary operator. Which even I don't think I like. =) So we should keep the wordy versions too. -David pull goes the weasel Green
Re: pull put (Was: Angle quotes and pointy brackets)
David Green writes: I guess we could always use prepend/append, pull/pop. No! Cpush and Cpop are a well-defined pair, not just in Perl, for dealing with stacks; we should keep those as they are. (And no synonyms, before somebody suggests any!) Smylers
Re: Arglist I/O [Was: Angle quotes and pointy brackets]
Larry Wall wrote:
But here's the kicker. The null filename can again represent the
standard filter input, so we end up with Perl 5's
while () {...}
turning into
for = {...}
Two more issues: idiom, and topification
= Topification:
There are cases in P5 when I *don't* want
while () {...}
but prefer
while ($input = ) {...}
so that I can have something else be the topic. Every example to date
has used Cfor:
for .lines {...}
but that sets the topic. I'm a little fuzzy on this, but doesn't Cfor
play topic games even in this?
for .lines - $input { ... $input ... }
That is, even though $_ remains unaffected, doesn't this affect
smartmatch etc.?
= Idiom:
The other concern is idiom. Using Cfor suggests start at the
beginning, continue to the end. OTOH, using Cwhile is a little
weaker -- keep doing this until it's time to stop. Obviously they'll
usually be used in the same way:
for = {...} vs. while () {...}
This seems a subtle concern, and maybe it's just my latent fear of
change making me uncomfortable, but I actually *think* in english -- not
that it does much good -- and this isn't how I think.
Can we ditch Cfor in the examples in favor of Cwhile, for a while? :)
=Austin
Re: pull put (Was: Angle quotes and pointy brackets)
Smylers wrote: Larry Wall writes: But then are we willing to rename shift/unshift to pull/put? Yes. Cunshift is a terrible name; when teaching Perl I feel embarrassed on introducing it. No! But I'd be willing to rename them to get/put. 'Pull' is the opposite of 'push', but 'pop' already works. Given the nature of many of the other changes in Perl 6, completely changing regexps for example, renaming a couple of functions seems minor. Agreed. Smylers =Austin
Re: Arglist I/O [Was: Angle quotes and pointy brackets]
On Dec 6, 2004, at 7:38 AM, Austin Hastings wrote:
for = {...}
I dub the...the fish operator!
:-)
David
Re: Arglist I/O [Was: Angle quotes and pointy brackets]
On Mon, Dec 06, 2004 at 09:06:22AM -0800, David Wheeler wrote:
: On Dec 6, 2004, at 7:38 AM, Austin Hastings wrote:
:
:for = {...}
:
: I dub the...the fish operator!
:
: :-)
Mmm. Next thing you'll know, people will name their files oddly just so
they can write things like:
for =///º {...}
for =|||' {...}
for =###* {...}
for =]]]° {...}
for =)))º {...}
Larry
Topification [Was: Arglist I/O [Was: Angle quotes and pointy brackets]]
On Mon, Dec 06, 2004 at 10:38:10AM -0500, Austin Hastings wrote:
: Two more issues: idiom, and topification
:
: = Topification:
:
: There are cases in P5 when I *don't* want
:
: while () {...}
:
: but prefer
:
: while ($input = ) {...}
:
: so that I can have something else be the topic. Every example to date
: has used Cfor:
:
: for .lines {...}
:
: but that sets the topic. I'm a little fuzzy on this, but doesn't Cfor
: play topic games even in this?
:
: for .lines - $input { ... $input ... }
:
: That is, even though $_ remains unaffected, doesn't this affect
: smartmatch etc.?
Currently it does. There have been some rumblings in the design team
that maybe it shouldn't. But it occurs to me that this might be another
spot to have our cake and eat it to. We could say that
for @foo - $input { ... $input ... }
doesn't set the topic in the block by default. However, methods do set
the topic (though there have been rumblings about that too). So we could
simply say that pointy subs can also be pointy methods if you specify
an invocant:
for @foo - $input: { ... $input and $_ ... }
I think I like that, but it needs to be thunk about some more. The downside
is that it's rather subtle. The upside is that it falls out of existing
rules, and lets - map more naturally in the way people expect. I don't
think people will naturally expect - to clobber $_.
Larry
while idiom [Was: Arglist I/O [Was: Angle quotes and pointy brackets]]
On Mon, Dec 06, 2004 at 10:38:10AM -0500, Austin Hastings wrote:
: = Idiom:
:
: The other concern is idiom. Using Cfor suggests start at the
: beginning, continue to the end. OTOH, using Cwhile is a little
: weaker -- keep doing this until it's time to stop. Obviously they'll
: usually be used in the same way:
:
: for = {...} vs. while () {...}
:
: This seems a subtle concern, and maybe it's just my latent fear of
: change making me uncomfortable, but I actually *think* in english -- not
: that it does much good -- and this isn't how I think.
:
: Can we ditch Cfor in the examples in favor of Cwhile, for a while? :)
Okay. Have an example:
while =$IN - $line {...}
I think that works. I'm back to thinking unary = in scalar context iterates
like p5's , and you should use extraordinary means to get extraordinary
results:
while file $IN - $blob {...}
while slurp $IN - $bigblob {...}
Larry
Re: Arglist I/O [Was: Angle quotes and pointy brackets]
Or even the dead fish operator:
while =###x - $net {...}
And here's a flounder:
while =:
Larry
Re: pull put (Was: Angle quotes and pointy brackets)
On Mon, Dec 06, 2004 at 10:45:22AM -0500, Austin Hastings wrote: : But I'd be willing to rename them to get/put. If I went with get, the opposite would be unget for both historical and huffmaniacal reasons. Larry
Re: Arglist I/O [Was: Angle quotes and pointy brackets]
David Wheeler wrote:
On Dec 6, 2004, at 7:38 AM, Austin Hastings wrote:
for = {...}
I dub the...the fish operator!
:-)
Back before there was a WWW, I used an editor called tgif. It was
written in france, and part of the idiom was to have two GUI buttons
showing respectively the head ( * ) and tail ( ( ) parts of a
fish. This were graphical images, please forgive my poor ascii drawing.
It took me a while to figure it out, but it was a cute bit of
bilingualism. (Or perhaps it was a bit of bilingual cute-ism...)
=Austin
Re: Topification [Was: Arglist I/O [Was: Angle quotes and pointy brackets]]
Larry Wall writes:
Currently it does. There have been some rumblings in the design team
that maybe it shouldn't. But it occurs to me that this might be another
spot to have our cake and eat it to. We could say that
for @foo - $input { ... $input ... }
doesn't set the topic in the block by default. However, methods do set
the topic (though there have been rumblings about that too). So we could
simply say that pointy subs can also be pointy methods if you specify
an invocant:
for @foo - $input: { ... $input and $_ ... }
I think I like that, but it needs to be thunk about some more. The downside
is that it's rather subtle. The upside is that it falls out of existing
rules, and lets - map more naturally in the way people expect. I don't
think people will naturally expect - to clobber $_.
Considering that I was the rumbler, I'll try to stay concise. Don't
think that this is anything more than a stormy brain, though.
I really like the fact that for always topicalizes. I like it because
it forces refactors where they ought to be happening. I always get
confused when I see:
for (@array) {
for my $row (@{$data-[$_]}) {
for my $element (@$row) {
foobar($_) if $element;
}
}
}
It works that way in natural languages too. If you try to use it too
remotely, you just confuse everybody. In particular:
For each element in @array, look up the corresponding $row in $data,
and for each $element in the $row, call foobar on it if $element is
true.
Call foobar on what?
The remaining problem is what to do about unary dot. Repeated here for
the, er, benefit? of p6l:
class Duple {
has $.left;
has $.right;
method perform (oper) {
oper($.left);
oper($.right);
}
}
Let's change that into a Tuple class:
class Tuple {
has @.elems;
method perform (oper) {
for @.elems {
.perform($_);
}
}
}
Can you find the mistake?
Luke
Re: while idiom [Was: Arglist I/O [Was: Angle quotes and pointy brackets]]
On Mon, Dec 06, 2004 at 09:56:57AM -0800, Larry Wall wrote:
On Mon, Dec 06, 2004 at 10:38:10AM -0500, Austin Hastings wrote:
: Can we ditch Cfor in the examples in favor of Cwhile, for a while? :)
Okay. Have an example:
while =$IN - $line {...}
I think that works. I'm back to thinking unary = in scalar context iterates
like p5's
What would these do?
while =$IN - $l1,$l2 {...}
while =$IN - @x {...}
That first one seems particularly useful. I'm not exactly sure what
the second one should do, but it seems like it should be similar to
{ my @x = $IN.slurp; ... }
Can it be that unary = in n-ary context iterates like p5's except
when n == Inf or n == 0 (which are list and void context I guess) ?
-Scott
--
Jonathan Scott Duff
[EMAIL PROTECTED]
Re: pull put (Was: Angle quotes and pointy brackets)
If I went with get, the opposite would be unget for both historical and huffmaniacal reasons. But get has too strong a class accessor connotation in most OO. unpull? ;-)
Re: while idiom [Was: Arglist I/O [Was: Angle quotes and pointy brackets]]
On Mon, Dec 06, 2004 at 12:45:18PM -0600, Jonathan Scott Duff wrote:
: On Mon, Dec 06, 2004 at 09:56:57AM -0800, Larry Wall wrote:
: On Mon, Dec 06, 2004 at 10:38:10AM -0500, Austin Hastings wrote:
: : Can we ditch Cfor in the examples in favor of Cwhile, for a while? :)
:
: Okay. Have an example:
:
: while =$IN - $line {...}
:
: I think that works. I'm back to thinking unary = in scalar context iterates
: like p5's
:
: What would these do?
:
: while =$IN - $l1,$l2 {...}
: while =$IN - @x {...}
:
: That first one seems particularly useful. I'm not exactly sure what
: the second one should do, but it seems like it should be similar to
: { my @x = $IN.slurp; ... }
The Cwhile statement is not an arbiter of lists. It want a scalar
value that can play the bool role. Assuming that $IN is really $*IN,
they would both fail because you're trying to bind a scalar string
to a signature that doesn't accept a single scalar string. It would
be exactly like
sub foo($I1, $I2) {...}
foo(#!/usr/bin/perl\n); # missing $I2
sub bar(@x) {...}
bar(#!/usr/bin/perl\n); # Trying to bind non-string to @x
That being said, if =$iterator returns a list of array references, the
second one would work. I don't see any way to make the first one work.
: Can it be that unary = in n-ary context iterates like p5's except
: when n == Inf or n == 0 (which are list and void context I guess) ?
You mean slurps all the values and then throws away all but n of them?
That's how p5's currently behaves. Or did you mean scalar ?
In any event, I don't think Cwhile is ever going to provide an n-ary
context to whatever it wants a boolean value from. That's what Cfor
is for.
Larry
Re: while idiom [Was: Arglist I/O [Was: Angle quotes and pointy brackets]]
On Mon, Dec 06, 2004 at 10:59:18AM -0800, Larry Wall wrote:
On Mon, Dec 06, 2004 at 12:45:18PM -0600, Jonathan Scott Duff wrote:
: On Mon, Dec 06, 2004 at 09:56:57AM -0800, Larry Wall wrote:
: On Mon, Dec 06, 2004 at 10:38:10AM -0500, Austin Hastings wrote:
: : Can we ditch Cfor in the examples in favor of Cwhile, for a while?
:)
:
: Okay. Have an example:
:
: while =$IN - $line {...}
:
: I think that works. I'm back to thinking unary = in scalar context
iterates
: like p5's
:
: What would these do?
:
: while =$IN - $l1,$l2 {...}
: while =$IN - @x {...}
:
: That first one seems particularly useful. I'm not exactly sure what
: the second one should do, but it seems like it should be similar to
: { my @x = $IN.slurp; ... }
The Cwhile statement is not an arbiter of lists.
Okie.
In any event, I don't think Cwhile is ever going to provide an n-ary
context to whatever it wants a boolean value from. That's what Cfor
is for.
Somehow I knew you were going to say that. I'm just being reluctant
to use Cfor for something I've been using Cwhile for all this time.
-Scott
--
Jonathan Scott Duff
[EMAIL PROTECTED]
Re: pull put (Was: Angle quotes and pointy brackets)
Dan Brian wrote: If I went with get, the opposite would be unget for both historical and huffmaniacal reasons. But get has too strong a class accessor connotation in most OO. unpull? ;-) pushf/popf. f is for front. But I still don't see anything wrong with shift/unshift. I'd prefer to avoid having a group of words that all mean about the same thing, but keeping them straight requires some memory trick. I program in too many languages to keep my mnemonics straight. There's going to be enough fun with is/has/does/but. For reference, I always have to do a 'perldoc perlvar' when I need a P5 $punct. -- Rod Adams
Re: pull put (Was: Angle quotes and pointy brackets)
On Mon, Dec 06, 2004 at 01:25:29PM -0600, Rod Adams wrote: Dan Brian wrote: If I went with get, the opposite would be unget for both historical and huffmaniacal reasons. But get has too strong a class accessor connotation in most OO. unpull? ;-) pushf/popf. f is for front. Ew! I'd prefer :head/:tail modifiers to push/pop over that. But ... But I still don't see anything wrong with shift/unshift. Neither do I. -Scott -- Jonathan Scott Duff [EMAIL PROTECTED]
Re: pull put (Was: Angle quotes and pointy brackets)
On Mon, Dec 06, 2004 at 11:52:22AM -0700, Dan Brian wrote: : If I went with get, the opposite would be unget for both historical : and huffmaniacal reasons. : : But get has too strong a class accessor connotation in most OO. : : unpull? ;-) Given the existence of a unary = for abbreviated use, I'd probably stick with shift/unshift. (Presumably changing the semantics of shift from p5 to be list/scalar/n-ary context sensitive, so you'd have to write scalar shift to get Perl 5's shift semantics in list context.) Though it's awfully tempting to fill in the holes in the periodic table: ($a, $b, $c) = @foo * 3; And then just say all the corresponding unaries default to 1 (or the arity of the left): $bit = + $number; # $number + 1 $graph = ~ $string; # chip()/chimp() $whether = ? $boolean;# presumably clears $boolean $elem = * $iterator; # shift $iterator That would mean that we couldn't use those unaries in front of ... though. I suppose unary * would mean pop. Blurch. Let's stick with the binaries, if we add 'em at all. I do think foo( @bar * 3 ) foo( @bar * 3 ) might actually be clearer than foo( splice(@bar,0,3) ) foo( splice(@bar,-3,3) ) Also, note that neither of the latter examples means the same as foo( pop(@bar,3) ) since pop would presumably pop them in reverse order from splice. We also get all the rotates if we allow * and *. On the other hand, if anyone suggests a list xor: @foo *^ @bar I'll ask whether they mean @foo »+^« @bar @foo »~^« @bar @foo »?^« @bar @foo »*^« @bar Larry
Re: Topification [Was: Arglist I/O [Was: Angle quotes and pointy brackets]]
Luke Palmer wrote:
The remaining problem is what to do about unary dot. Repeated here for
the, er, benefit? of p6l:
class Duple {
has $.left;
has $.right;
method perform (oper) {
oper($.left);
oper($.right);
}
}
Let's change that into a Tuple class:
class Tuple {
has @.elems;
method perform (oper) {
for @.elems {
.perform($_);
}
}
}
Can you find the mistake?
Well it's not using oper on the elems anymore.
method perform (oper) {
for @.elems {
oper($_);
}
}
But I don't think that was the mistake you were talking about. And I
don't see what it has to do with unary dot either, because you don't
need to use unary dot to implement that method. Unless each member of
@.elems is a Duple, in which case the class isn't one I'd call Tuple.
Sorry, nitpicking level seems to be set to 9 at the moment. What did you
mean?
Re: pull put (Was: Angle quotes and pointy brackets)
Larry Wall wrote:
On Mon, Dec 06, 2004 at 11:52:22AM -0700, Dan Brian wrote:
: If I went with get, the opposite would be unget for both historical
: and huffmaniacal reasons.
Why? (I get the huffman, not the history.) Is it just a nod to unshift?
Given the existence of a unary = for abbreviated use, I'd probably
stick with shift/unshift. (Presumably changing the semantics of
shift from p5 to be list/scalar/n-ary context sensitive, so you'd
have to write scalar shift to get Perl 5's shift semantics
in list context.)
What about add/remove?
sub unshift(@a, [EMAIL PROTECTED])
{
@a.add(@items);
}
We could add :head and :tail, with :head the default, and let push|pop
be equivalent to (add|remove).assuming(tail = 1)
As a side note, other than historical consistency, is there a good
reason for push/pop to use the end of the array? I'd argue that for a
stack, you only want to know one address: @stack[0] -- the 'top' of
the stack -- and if you ever iterate a stack you're inclined to see the
items in distance-from-top order, making 0..Inf the right array
sequence. If we're going to reorg the function space, let's huffmanize
the stack stuff (push/pop/0) and let the other stuff go hang.
=Austin
Re: pull put (Was: Angle quotes and pointy brackets)
On Mon, Dec 06, 2004 at 03:50:42PM -0500, Austin Hastings wrote:
: Larry Wall wrote:
:
: On Mon, Dec 06, 2004 at 11:52:22AM -0700, Dan Brian wrote:
: : If I went with get, the opposite would be unget for both historical
: : and huffmaniacal reasons.
:
:
: Why? (I get the huffman, not the history.) Is it just a nod to unshift?
Try man ungetc.
: Given the existence of a unary = for abbreviated use, I'd probably
: stick with shift/unshift. (Presumably changing the semantics of
: shift from p5 to be list/scalar/n-ary context sensitive, so you'd
: have to write scalar shift to get Perl 5's shift semantics
: in list context.)
:
:
: What about add/remove?
Backwards Huffman, considering removal happens more often.
: sub unshift(@a, [EMAIL PROTECTED])
: {
: @a.add(@items);
: }
:
: We could add :head and :tail, with :head the default, and let push|pop
: be equivalent to (add|remove).assuming(tail = 1)
remove is a transitive verb. I think people would take remove
to be remove any occurrences of, and in the absence of any obvious
direct object, remove this array, or remove the list of files in
this array.
: As a side note, other than historical consistency, is there a good
: reason for push/pop to use the end of the array? I'd argue that for a
: stack, you only want to know one address: @stack[0] -- the 'top' of
: the stack -- and if you ever iterate a stack you're inclined to see the
: items in distance-from-top order, making 0..Inf the right array
: sequence. If we're going to reorg the function space, let's huffmanize
: the stack stuff (push/pop/0) and let the other stuff go hang.
For indexable arrays, the front is what you want to nail down, but
that means it's difficult to make unshift efficient. Swapping push/pop
for shift/unshift would make push/pop rather inefficient. And the top
of your stack can just as easily be @stack[-1] as it is now.
I don't see much reason to change what we have currently unless we
decided shift was too long, and it isn't if we have unary = for
interators, and real function args to take away most of my $arg = shift;.
Appearances to the contrary notwithstanding, I'm not trying to break
Perl 5 constructs just for the heck of it.
Larry
Re: Topification [Was: Arglist I/O [Was: Angle quotes and pointy brackets]]
Matthew Walton writes:
Luke Palmer wrote:
The remaining problem is what to do about unary dot. Repeated here for
the, er, benefit? of p6l:
class Duple {
has $.left;
has $.right;
method perform (oper) {
oper($.left);
oper($.right);
}
}
Let's change that into a Tuple class:
class Tuple {
has @.elems;
method perform (oper) {
for @.elems {
.perform($_);
}
}
}
Can you find the mistake?
Well it's not using oper on the elems anymore.
That's mostly because I really screwed up the example. Mind, it was
very, very early in the morning when I wrote this. Let's try again.
(This is a pretty trivial example, but the problem only gets worse as we
approach real life).
class MyStream {
has $.stream;
method :send_one ($item) {
$.stream.send($item);
}
method send ([EMAIL PROTECTED]) {
.:send_one(BEGIN);
for @data {
.:send_one($_);
}
.:send_one(END);
}
}
Luke
Re: Topification [Was: Arglist I/O [Was: Angle quotes and pointy brackets]]
Luke Palmer wrote:
class MyStream {
has $.stream;
method :send_one ($item) {
$.stream.send($item);
}
method send ([EMAIL PROTECTED]) {
.:send_one(BEGIN);
for @data {
.:send_one($_);
}
.:send_one(END);
}
}
I'll guess that you're pointing at
.:send_one($_);
Which supposedly uses topic to resolve .:send_one into $this.send_one.
If that works, then I'm happy -- I like being able to control topic and
$_ differently. But if Cfor changes topic, then what?
OUTER::.:send_one($_);
Yuck.
=Austin
Re: pull put (Was: Angle quotes and pointy brackets)
stuff grab :-) -- Mark Biggar [EMAIL PROTECTED] [EMAIL PROTECTED] [EMAIL PROTECTED] -- Original message -- On Mon, Dec 06, 2004 at 10:45:22AM -0500, Austin Hastings wrote: : But I'd be willing to rename them to get/put. If I went with get, the opposite would be unget for both historical and huffmaniacal reasons. Larry
Re: pull put (Was: Angle quotes and pointy brackets)
On Mon, 6 Dec 2004 11:34:24 -0800, Larry Wall [EMAIL PROTECTED] wrote:
Though it's awfully tempting to fill in the holes in the periodic table:
($a, $b, $c) = @foo * 3;
And then just say all the corresponding unaries default to 1 (or the arity
of the left):
$bit = + $number; # $number + 1
$graph = ~ $string; # chip()/chimp()
$whether = ? $boolean;# presumably clears $boolean
$elem = * $iterator; # shift $iterator
Well, that's interesting.
I suppose unary * would mean pop. Blurch. Let's stick with the binaries,
if we add 'em at all. I do think
foo( @bar * 3 )
foo( @bar * 3 )
Hrm... if you're thinking of going that way, I'd rather have a
lazy-assignment/destructive-pipe operator of some sort:
($a,$b) == [EMAIL PROTECTED]; # splice(@bar, 0, 2)
($a, $b) == [EMAIL PROTECTED] # splice(@bar, 0, 0, $a, $b)
[EMAIL PROTECTED] == ($a, $b); # splice(@bar, -2)
[EMAIL PROTECTED] == ($a, $b); # splice(@bar, @bar, 0, $a, $b);
Of course, with something indicating the desire to modify the array. I
don't know that [EMAIL PROTECTED] would be right for that, but I dunno. Just an
idea.
I'd want some way of telling the array to lazily add/remove elements
as part of the pipe operator, which would make:
foo == [EMAIL PROTECTED]; # REMOVE however many elements from the front of
@bar
as foo() wants
However, this would lead to me thinking about this sequence:
[EMAIL PROTECTED] == map == grep == @whatever;
as:
while pop @this { ... unshift @that, $_ }
Which would be interesting (bad) for performance
Ashley
Re: pull put (Was: Angle quotes and pointy brackets)
Dan Brian writes: If there's a willingness to rename shift/unshift, why not consider going a bit further (and offend shell heritage) to note that pull/put aren't really linguistically opposed either (unlike push/pull). Why not rename pop to pull, and use something like put/take for shift/unshift? Having push and pull operate on opposite ends of an array strikes me as more confusing than even shift. When it comes to adding and removing elements, shouldn't there be semantic opposition for functions that operate on the same end? I don't think that's a good time. It kills the array-as-stack idiom, which, well, everybody uses all the time. I don't mind the linguistic nonopposition of pull/put. The main thing I don't like is the alliteration between push/pop. That makes for very difficult mnemonics. Obviously, the CS-literate can just remember that they're the nonstack ops, but many Perlers are Shellers and Adminers, without being CSers. I've actually been happy with shift/unshift. But what we'd really like to do is: given the user knows what push/pop do, what would they *guess* to mean shift (I tend to think that this is a very good technique for naming). And, well, I'm thinking pull. So it's a toss-up between shift/unshift and put/pull. Luke
Re: Angle quotes and pointy brackets
On Thursday, December 2, 2004, 10:08:31 AM, you (mailto:[EMAIL PROTECTED]) wrote: On Tue, 30 Nov 2004, Austin Hastings wrote: How about just having C system() return a clever object with .output and .err methods? interesting... Michele Prior art of this on Windows... http://msdn.microsoft.com/library/en-us/script56/html/wslrfExecMethod.asp (the respective properties on the returned WshScriptExec instance being .StdOut and .StdErr.) -- Richard mailto:[EMAIL PROTECTED]
Re: pull put (Was: Angle quotes and pointy brackets)
If there's a willingness to rename shift/unshift, why not consider going a bit further (and offend shell heritage) to note that pull/put aren't really linguistically opposed either (unlike push/pull). Why not rename pop to pull, and use something like put/take for shift/unshift? That goes way beyond offending shell heritage. That actively opposes sixty years of computer science terminology setting push and pop in opposition. I'm not objecting to pop, but pull in opposition to push, on the other side of the array.
Re: pull put (Was: Angle quotes and pointy brackets)
Dan Brian writes: Having push and pull operate on opposite ends of an array strikes me as more confusing than even shift. It makes good sense to me -- if we're trying to move a piano from you to me then either you can push or your end or I can pull on my end: we're operating on different ends of it, but the effect in both cases is moving in one direction. Now instead of a piano imagine one of those conveyor belts that you get at supermarket checkouts: you push your goods on one-end, and the cashier pulls them off the other. When the cashier pulls one item off that unbreaks the light beam to the sensor, which triggers the motor, and all the other items get pulled along too, moving one place along. Smylers
Re: pull put (Was: Angle quotes and pointy brackets)
It makes good sense to me -- if we're trying to move a piano from you to me then either you can push or your end or I can pull on my end: we're operating on different ends of it, but the effect in both cases is moving in one direction. As a mnemonic for remembering which side push/pull operate on, I agree. (A stalled car etc.) It would be nice if the corresponding functions could similarly be opposed without the potential confusion for beginners, but I realize that may not be possible, and your example is at least convincing that it's better than shift/unshift.
Re: pull put (Was: Angle quotes and pointy brackets)
Larry Wall writes: But then are we willing to rename shift/unshift to pull/put? Yes. Cunshift is a terrible name; when teaching Perl I feel embarrassed on introducing it. Given the nature of many of the other changes in Perl 6, completely changing regexps for example, renaming a couple of functions seems minor. Smylers
Re: Arglist I/O [Was: Angle quotes and pointy brackets]
Okay, maybe I should have gone to bed, but I kept thinking about this.
I'm starting to suspect it's time to haul out the operator I've
been holding in reserve for lo these many years now, the unary =.
Suppose we say that it iterates iterators, but also it recognizes
certain things that aren't iterators and turns them into iterators
and iterates them. So you can say
for =$*IN {...}
for =$*ARGS {...}
if you like, but it also recognizes filenames, and lists of filehandles,
and lists of filenames, and in list context turns them into lists of
lines:
for =foo.c {...}
for =foo.c foo.h {...}
for =«$foo.c $foo.h» {...}
for =['foo.c', 'foo.h'] {...}
for =['.myrc', @*ARGS] {...}
for [EMAIL PROTECTED] {...}
You can think of the = as a picture of the lines in the file, and
read it lines of. Well, in list context anyway. In scalar context,
it would do a slurp:
$file = =foo.c;
But here's the kicker. The null filename can again represent the
standard filter input, so we end up with Perl 5's
while () {...}
turning into
for = {...}
It's just all the magic is done by the = operator rather than the
, which is just a plain old ordinary null string inside newfangled
angle quotes. I suppose =() or =[] or = would work just as well,
but somehow = is what I expect convention to settle on, for certain
values of hysterical and raisins.
And yes, I've looked at every other character on the keyboard, and
several that aren't on the keyboard. And no, I don't think it'll
cause many parsing difficulties since we changed the parsing rules
on methods to require parentheses if there are arguments. It's only
a problem after 0-or-1-ary operators, and not really a problem there,
since the default is to look for a term, and there aren't many 0-or-1-ary
operators you'd want to assign to anyway. In particular, you can say
things like:
print =foo.c;
And I don't think it'll be visually confusing to people who put spaces
on both sides of their assignment operators.
Larry
Re: Arglist I/O [Was: Angle quotes and pointy brackets]
On Fri, Dec 03, 2004 at 06:38:42PM -0800, Larry Wall wrote:
: Might even just be a global multi sub that defaults to $*ARGS:
:
: multi sub *lines (IO ?$handle = $*ARGS) {...}
: multi sub *lines (Str $filename) {...}
: multi sub *lines (IO @handle) {...}
: multi sub *lines (Str @filenames) {...}
:
: Then the filter call would be quite hypoallergenic:
:
: for lines {...}
Except that won't parse right, drat it. It won't know whether to expect
a term or an operator at the left bracket. Can't use a 0-or-1-ary
as the last thing in the list. That was the advantage of .lines, which
we could tell had no arguments, since methods with arguments must use
parens.
Don't wanna go back to bare * either; I've since made it a synonym
for Any. Plus it also suffers the 0-or-1 problem. It would still
work as a unary, if we can figure out something really short to mean
$*ARGS.
[Much bogus random brainstorming deleted.]
Well, I just need to think about it some more. I've already believed
six impossible things after dinner, so maybe I'd better go to bed.
Larry
Re: iteration (was Re: Angle quotes and pointy brackets)
In article [EMAIL PROTECTED],
[EMAIL PROTECTED] (Matt Diephouse) wrote:
What I mean is that Perl takes an array and makes an iterator out of it.
Sure, you probably don't think about it like that, but the behavior is
the same (who says arrays need to iterate starting at element zero?).
I probably didn't, but over the last couple of days I've been thinking
about it like that more and more.
The odd thing is that here we are designing Perl 6, and we're trying
to take an iterator and make it into an array so that we can turn it
back into an iterator again. It seems like we should just use it as an
iterator::
for $iterator - $elem { ... }
Yes!
Supposing
class Filehandle does Iterate; # Iterate or Iterator?
we have an easy way to create new iterators. I'm not sure how useful
they would be in Perl 6
Maybe the class doesn't do it, but one of its methods does? Then you
can call it whatever makes sense.
class Filehandle
{ method next is iterator {...} }
class Monarch
{ method succeed is iterator {} }
class Blockbuster
{ method sequel is iterator { $.title++; return $self; } }
(how do iterators compare to lazy lists?)
Aren't lazy lists a funny kind of iterator? Ones that memoise their
results. And supply an indexing method [].
Which be even cuter like this (I think):
for iter($sth.execute) - $results { ... }
where iter creates an Iterator object that just knows to call C.next
on its argument.
That still seems too cumbersome to me. Isn't it for that knows to
call .next (or .sequel, whatever)? I'm thinking that that is the
point of for $foo, which should be approximately the same as while
$foo.next. We've got while for looping, .next for iterating,
and for for doing both in one convenient little shortcut.
So lists and arrays would be iterators, although they may not flaunt it
in public. But you could always explicitly call their .next method if
you wanted to. For example,
for @lines
{
if s/\\$// # ends with a backslash = continued on next line
{
$_ ~= @lines.next;
redo;
}
# now process our joined line ...
}
Of course, that's just the example for redo from the Camel, except
using an array instead of . A P5 array wouldn't have worked, because
there's no way to get the next iteration of an array in the way that
you can use a scalar to read the next line of the file. (Though
there ought to be a better way of referring to the object of the for
-- I had to refer to it by name here, but I couldn't do that if it were
a list; and $_ is already taken. @_ strikes me as reasonable (for a
not necessarily very large value of reasonable).)
I'm not sure how much extra syntax is needed. Something that's
expected to iterate (like a filehandle) should just iterate naturally
when used in scalar context, or list context, or both. (But a
filehandle might stringify to the filename in string context, and
return the filehandle object itself when being passed to a function
looking for a filehandle.)
Something that isn't typically expected to iterate (like an array)
could use its .next method, which is a tad wordy, but that's good
because that makes it clear and obvious that we are explicitly
iterating.
Presumably you could slurp up all the iterations at once using * or
** to flatten them. That still doesn't get us the magical because
it's really a double iteration (over the filenames in @ARGS and then
over the contents of each file). In fact, that's just a specific case
of wanting to loop through several iterators -- Cfor $iter1, $iter2,
$iter3 {...} only loops through the *list* of iterators, not through
each object itself.
So maybe we do need Larry's new [EMAIL PROTECTED] to get that kind of
double-iteration (without having to nest for loops, ugh!). Hm.
Unless the flattening operator will take care of that. Cfor
*$iter1, *$iter2, *$iter3 {...} would do it, but I'm not sure about
Cfor [EMAIL PROTECTED] {...}. (It would definitely do *something*, of that
I'm fairly confident!)
But I'm starting to think I may have just been thinking the original
problem all along, only inside-out
Hoping I haven't removed all doubt of my foolishness,
I'm hoping this reply reassures you.
- David at risk of removing all doubts of mine Green
Re: iteration (was Re: Angle quotes and pointy brackets)
On Sat, 04 Dec 2004 08:59:24 -0700, David Green [EMAIL PROTECTED] wrote:
In article [EMAIL PROTECTED],
[EMAIL PROTECTED] (Matt Diephouse) wrote:
Supposing
class Filehandle does Iterate; # Iterate or Iterator?
we have an easy way to create new iterators. I'm not sure how useful
they would be in Perl 6
Maybe the class doesn't do it, but one of its methods does? Then you
can call it whatever makes sense.
Cdoes Iterate signifies a role named Iterate. Roles are sort of a
mix of interfaces and mixins (as I understand it -- I'm still waiting
for E12). So saying a class fulfills a role just means that it
provides certain methods. In this case, I was saying class with the
Iterate role would provide a C.next method.
Which be even cuter like this (I think):
for iter($sth.execute) - $results { ... }
where iter creates an Iterator object that just knows to call C.next
on its argument.
That still seems too cumbersome to me. Isn't it for that knows to
call .next (or .sequel, whatever)? I'm thinking that that is the
point of for $foo, which should be approximately the same as while
$foo.next. We've got while for looping, .next for iterating,
and for for doing both in one convenient little shortcut.
But for needs to know if it has an iterator or a list. You don't want
it iterating over things you didn't want it iterating. In this case, I
was suggesting making an, though I suppose something like
C$sth.execute could just return one.
Hoping I haven't removed all doubt of my foolishness,
I'm hoping this reply reassures you.
Thanks.
--
matt diephouse
http://matt.diephouse.com
Re: Arglist I/O [Was: Angle quotes and pointy brackets]
On Sat, 4 Dec 2004 01:37:00 -0800, Larry Wall [EMAIL PROTECTED] wrote:
for =$*IN {...}
for =$*ARGS {...}
Yay. A generalised form of the input operator, which can create even
handier idioms for simple file processing. Maybe I wasn't clear
enough. My issue wasn't specifically with '.lines' for filter
behaviour -- as a replacement solely for the while () { ... } idiom,
it would be quite adequate. But as a replacement for OPENEDFILE, it
is (IMO) sub-par, and definitely does add to the length of the whole.
As for the nuclear blackmail argument: One of the prime reasons I
like Perl is that different things look different. When everything
starts looking like a method call, that distinction rapidly drops
away.
$file = =foo.c;
Huh. That's really kinda neat.
But here's the kicker. The null filename can again represent the
standard filter input, so we end up with Perl 5's
while () {...}
turning into
for = {...}
Which is really short for 'for [EMAIL PROTECTED] {...}', then?
--
Schwäche zeigen heißt verlieren;
härte heißt regieren.
- Glas und Tränen, Megaherz
Re: Arglist I/O [Was: Angle quotes and pointy brackets]
Larry Wall wrote:
So you can say
for =$*IN {...}
for =$*ARGS {...}
for =foo.c {...}
for =foo.c foo.h {...}
for =«$foo.c $foo.h» {...}
for =['foo.c', 'foo.h'] {...}
for =['.myrc', @*ARGS] {...}
for [EMAIL PROTECTED] {...}
for = {...}
The simplicity is nice, but the visual message is, well, icky.
It might be salvageable by having the ='s balance, yielding:
for =$*IN= {...}
for =$*ARGS= {...}
for =foo.c= {...}
for =foo.c foo.h= {...}
for =«$foo.c $foo.h»= {...}
for =['foo.c', 'foo.h']= {...}
for =['.myrc', @*ARGS]= {...}
for [EMAIL PROTECTED] {...}
for == {...}
That looks better. Might even make the trailing = mean something useful
like auto-chomp.
And I don't think it'll be visually confusing to people who put spaces
on both sides of their assignment operators.
But those of us who often use the horizontal ws to break up the terms on
a line will moderately often not put spaces around our assignments and
less thans.
Okay, this rant is more about the \s\s than \s=\s. To me, it is easier
to understand the grouping of line 1 than line 2 below:
if( $a$b $c$d ) {...}
if( $a $b $c $d ) {...}
In line2, my mind has to stop and ask: is that ($a $b) ($c $d),
or $a ($b $c) $d. It quickly comes to the right answer, but the
question never comes up in the first line. If I wanted to use more
parens for clarity, I'd use LISP.
-- Rod Adams
Re: Arglist I/O [Was: Angle quotes and pointy brackets]
Rod Adams writes:
Okay, this rant is more about the \s\s than \s=\s. To me, it is easier
to understand the grouping of line 1 than line 2 below:
if( $a$b $c$d ) {...}
if( $a $b $c $d ) {...}
In line2, my mind has to stop and ask: is that ($a $b) ($c
$d), or $a ($b $c) $d. It quickly comes to the right answer,
but the question never comes up in the first line. If I wanted to use
more parens for clarity, I'd use LISP.
This is Perl. TMTOWTCI (Clarify It).
if ($a $b) ($c $d) {...}
if $a $b and $c $d{...}
if $a $b$c $d {...}
In particular, you need to ask yourself which you'd rather have:
$a$b with %hkey
$a $b with %hkey
But you might actually have to ask yourself. I'm still not sure... (and
I'm not even paying attention to the left side).
Luke
Re: Arglist I/O [Was: Angle quotes and pointy brackets]
On Fri, Dec 03, 2004 at 06:38:42PM -0800, Larry Wall wrote:
On Fri, Dec 03, 2004 at 06:43:05PM +, Herbert Snorrason wrote:
: This whole issue kind of makes me go 'ugh'. One of the things I like
: best about Perl is the amazing simplicity of the input construct.
Hmm.
while () {...}
for .lines {...}
Looks like a wash to me.
This is a neat win, keyboards favorise alphabetic characters that are
less excentred. Moreover, in some non qwerty layout, to make place for
diacritic characters, some non alphabetic characters are less
accessible, shift or alt-gr is necessary to type them.
Having being used to qwerty keyboards, on a french keyboard, I switch
from azerty to qwerty to program in C or Perl because of their heavy
ratio nonalpha/alpha. But most programmers use their native keyboard
layout.
--
stef
Re: Arglist I/O [Was: Angle quotes and pointy brackets]
On Sat, 04 Dec 2004 11:03:03 -0600, Rod Adams [EMAIL PROTECTED] wrote:
Larry Wall wrote:
for =$*IN {...}
for =$*ARGS {...}
for =foo.c {...}
for =foo.c foo.h {...}
for =$foo.c $foo.h {...}
for =['foo.c', 'foo.h'] {...}
for =['.myrc', @*ARGS] {...}
for [EMAIL PROTECTED] {...}
for = {...}
The simplicity is nice, but the visual message is, well, icky.
It might be salvageable by having the ='s balance, yielding:
for =$*IN= {...}
for =$*ARGS= {...}
hm. we have short and strange FH, for input.. (and for some reason, it
is bracketing! there's no sense at all in it)
..but we have long (and even looking slightly OOish, in perl5 sense) print
FH for output, and noone complained. We still aint going to have funny
syntax for output, and we not going to keep old syntax for input. Why to
reintroduce even more strangeness with that unary =, which is actually a
simple list operator, which doesn't desire for huffmanizing?
I don't think that would hurt anyone
for lines file1 file2 file3 {...}
# or
for files file1 file2 file3 {...}
# or
for lines @*ARGS {...}
# or just that special case:
for lines {...}
but actually everybody just miss that short and strange
while () {...}
and how all other handles would be accessed is much less concern.
it's just a bad and beloved habit, IMHO.
maybe we could make a special case.. (C programmers would be shocked)
for () {...}
Re: Arglist I/O [Was: Angle quotes and pointy brackets]
On Sat, 04 Dec 2004 11:03:03 -0600, Rod Adams [EMAIL PROTECTED] wrote:
Okay, this rant is more about the \s\s than \s=\s. To me, it is easier
to understand the grouping of line 1 than line 2 below:
if( $a$b $c$d ) {...}
if( $a $b $c $d ) {...}
In line2, my mind has to stop and ask: is that ($a $b) ($c $d),
or $a ($b $c) $d. It quickly comes to the right answer, but the
question never comes up in the first line. If I wanted to use more
parens for clarity, I'd use LISP.
I've got used to write it as
if( $a $b and $c $d) {...}
already. if it could help.. :)
Re: Arglist I/O [Was: Angle quotes and pointy brackets]
On Sat, Dec 04, 2004 at 11:02:38PM +0300, Alexey Trofimenko wrote:
: hm. we have short and strange FH, for input.. (and for some reason, it
: is bracketing! there's no sense at all in it)
: ..but we have long (and even looking slightly OOish, in perl5 sense) print
: FH for output, and noone complained. We still aint going to have funny
: syntax for output, and we not going to keep old syntax for input. Why to
: reintroduce even more strangeness with that unary =, which is actually a
: simple list operator, which doesn't desire for huffmanizing?
True, except for the fact that it *is* unary rather than list, so it
doesn't require parens to interpolate =$fh into a list. I had been
thinking that there should be a long form as well, just as we have
both !/not, and ?/true.
: I don't think that would hurt anyone
: for lines file1 file2 file3 {...}
: # or
: for files file1 file2 file3 {...}
: # or
: for lines @*ARGS {...}
: # or just that special case:
:
: for lines {...}
But that last one is the one that *doesn't* work if lines is a list operator.
List operators always expect a term, and {...} is recognized as a statement
block only where an operator is expected.
It would be parsed as:
for lines({...}) ???
: but actually everybody just miss that short and strange
: while () {...}
: and how all other handles would be accessed is much less concern.
: it's just a bad and beloved habit, IMHO.
Definitely beloved. Bad? I dunno. It's definitely visually distinct,
and that's why I put it into Perl that way in the first place. The data
flow of your program is only partially related to the control flow,
and something that is producing asynchronous data needs to stand out.
: maybe we could make a special case.. (C programmers would be shocked)
: for () {...}
I think that should just do nothing, so that a code generator can spit it
out without worrying about the special case. I still think the special
case is either of
for = {...}
or
for lines {...}
at the writer's discretion.
But I do like your lines/files distinction, which = doesn't make. Probably
if we distinguish them as list operators, we make the unary = only do
lines. Then in scalar context it just gives you the next line, which
will be more familiar to people coming from FH think.
I suppose we could also have
for words {...}
for tokens {...}
for paragraphs {...}
for chunks(, :delim(/^^===+\h*\n/)) {...}
etc.
On the other hand, if we follow the Perl 5 model, maybe = always
means chunks, and the filehandle just defaults to chunking into lines
like Perl 5's in the absence of a $/ redefinition. Presumably
words/tokens/lines/paragraphs/files would just synonyms for chunks in
that case. And maybe records/rows for people who don't like chunks. :-)
But I think people would expect something like words to override
the filehandle's natural chunking proclivities at least temporarily
in the case of a scalar input. So I think =$fh means chunks($fh),
the natural chunking of the filehandle (defaulting to lines), while
the words/files/paragraphs do temporary override of chunking policy.
Presumably there are also :words, :files, and :paragraphs adverbs on
the opening of the filehandle to set the default chunking. No reason
to make them different words. Or maybe they're all args to a single
:bywords adverb. And perhaps that also turns on autochomping.
Larry
Re: Arglist I/O [Was: Angle quotes and pointy brackets]
On Sat, Dec 04, 2004 at 11:08:38PM +0300, Alexey Trofimenko wrote:
On Sat, 04 Dec 2004 11:03:03 -0600, Rod Adams [EMAIL PROTECTED] wrote:
Okay, this rant is more about the \s\s than \s=\s. To me, it is easier
to understand the grouping of line 1 than line 2 below:
if( $a$b $c$d ) {...}
if( $a $b $c $d ) {...}
In line2, my mind has to stop and ask: is that ($a $b) ($c $d),
or $a ($b $c) $d. It quickly comes to the right answer, but the
question never comes up in the first line. If I wanted to use more
parens for clarity, I'd use LISP.
I've got used to write it as
if( $a $b and $c $d) {...}
already. if it could help.. :)
I agree with Rod - it is much more readable when there are
no blanks around the and there are blanks around the .
Typing is not the problem as much as reading, however, I choose
the spacing for readability when I type it, deciding what the
base chunks are and putting blanks aound the base chunks but
not within them. Having a few operators that require spacing
will be an extra gotcha to consider in that process, so it
will occassionably lead to syntax errors when I don't consider
the special rule; but it will still lead to less readable code
when I do remember the rule and leave the extra spaces.
--
Re: Arglist I/O [Was: Angle quotes and pointy brackets]
On Sat, Dec 04, 2004 at 01:24:41PM -0800, Larry Wall wrote:
: I suppose we could also have
:
: for words {...}
: for tokens {...}
: for paragraphs {...}
: for chunks(, :delim(/^^===+\h*\n/)) {...}
:
: etc.
I see a problem with
for words {...}
since there's likely to be a words method on strings. Maybe we want:
for fwords {...}
Er...on second thought, we probably just have to write:
for words = {...}
or
for words(lines()) {...}
instead. And of course, tokens() is silly unless you have defined a lexer.
Which leaves paragraphs(), which is not really common enough to do as other
than a mod to the filehandle. So it comes back to lines/chunks/files.
Larry
Re: iteration (was Re: Angle quotes and pointy brackets)
David Green [EMAIL PROTECTED] wrote: Aren't lazy lists a funny kind of iterator? Ones that memoise their results. And supply an indexing method []. As I mentioned the other day, I fail to see any material difference between an iterator and a lazy list, except that a few operations are allowed on a lazy list that aren't on an iterator. (And all of those could be emulated, albeit inefficiently, with one; even with a pipe, if the user does $pipe[1024], there's no technical reason you can't store the first thousand-odd lines and return the one they asked for.) Also note that there's no difference between iterating over a lazy copy of an array, and iterating over a lazy copy of a lazy copy of an array, except for the amount of indirection; thus, there would be no need for for() to distinguish between Cfor $array and Cfor $iter (though both of those forms might need a splat). -- Brent 'Dax' Royal-Gordon [EMAIL PROTECTED] Perl and Parrot hacker I might be an idiot, but not a stupid one. --c.l.p.misc (name omitted to protect the foolish)
Re: pull put (Was: Angle quotes and pointy brackets)
Smylers [EMAIL PROTECTED] wrote: Yes. Cunshift is a terrible name; when teaching Perl I feel embarrassed on introducing it. Cunshift's only virtue, IMHO, is that it's clearly the inverse of Cshift. But I think the spelling and aural relationship between Cpush, Cpop, Cpull, and Cput is clear enough to negate that. But then, I'm a little biased. -- Brent 'Dax' Royal-Gordon [EMAIL PROTECTED] Perl and Parrot hacker I might be an idiot, but not a stupid one. --c.l.p.misc (name omitted to protect the foolish)
Re: pull put (Was: Angle quotes and pointy brackets)
Brent 'Dax' Royal-Gordon wrote: Smylers [EMAIL PROTECTED] wrote: Yes. Cunshift is a terrible name; when teaching Perl I feel embarrassed on introducing it. Cunshift's only virtue, IMHO, is that it's clearly the inverse of Cshift. But I think the spelling and aural relationship between Cpush, Cpop, Cpull, and Cput is clear enough to negate that. But then, I'm a little biased. Except that push and pull are logical opposites linguistically, but not in standard CS parlance. could be very confusing. There's a possibility of using Cenq and Cdeq for enqueue/dequeue, except that Cdeq == Cpop in standard implementations. So Cenq and Cshift? yeck. -- Rod Adams
Re: pull put (Was: Angle quotes and pointy brackets)
Cunshift's only virtue, IMHO, is that it's clearly the inverse of Cshift. But I think the spelling and aural relationship between Cpush, Cpop, Cpull, and Cput is clear enough to negate that. But then, I'm a little biased. Except that push and pull are logical opposites linguistically, but not in standard CS parlance. could be very confusing. There's a possibility of using Cenq and Cdeq for enqueue/dequeue, except that Cdeq == Cpop in standard implementations. So Cenq and Cshift? yeck. If there's a willingness to rename shift/unshift, why not consider going a bit further (and offend shell heritage) to note that pull/put aren't really linguistically opposed either (unlike push/pull). Why not rename pop to pull, and use something like put/take for shift/unshift? Having push and pull operate on opposite ends of an array strikes me as more confusing than even shift. When it comes to adding and removing elements, shouldn't there be semantic opposition for functions that operate on the same end? (I realize that take is already ... taken, for control structures.)
Re: pull put (Was: Angle quotes and pointy brackets)
On Sat, 4 Dec 2004 23:33:24 -0700, Dan Brian [EMAIL PROTECTED] wrote: If there's a willingness to rename shift/unshift, why not consider going a bit further (and offend shell heritage) to note that pull/put aren't really linguistically opposed either (unlike push/pull). Why not rename pop to pull, and use something like put/take for shift/unshift? That goes way beyond offending shell heritage. That actively opposes sixty years of computer science terminology setting push and pop in opposition. (Well, maybe not *sixty* years, but you get the idea.) -- Brent 'Dax' Royal-Gordon [EMAIL PROTECTED] Perl and Parrot hacker I might be an idiot, but not a stupid one. --c.l.p.misc (name omitted to protect the foolish)
Re: Arglist I/O [Was: Angle quotes and pointy brackets]
On Fri, Dec 03, 2004 at 06:43:05PM +, Herbert Snorrason wrote:
: This whole issue kind of makes me go 'ugh'. One of the things I like
: best about Perl is the amazing simplicity of the input construct.
Hmm.
while () {...}
for .lines {...}
Looks like a wash to me.
: Replacing that with something that not only is object oriented, but on
: top of that also LOOKS object oriented is bound to be a loss. It's
: going to be that bit longer to write, and not the least bit easier to
: understand.
Really? I dare you to show those two lines to any random
computer-literate but non-Perl-speaking stranger and see which one
they understand better.
And actually, .lines *wins* on keystrokes if you count shift keys.
: Neither the conceptual input operator nor the extremely
: handy idiom for behave like a Unixy filter should go. Please.
It's all cargo cult at that level anyway, so whether it looks OO or not
is really completely immaterial to its usability.
If .lines loses out, it won't be because of any of your arguments, but
because $*ARGS maybe shouldn't be the topic of Main. But $*ARGS is
most certainly an object of some sort, whether or not we hide that fact
from the cargo culters.
: If you don't like the angles doing it, by all means take them. But
: don't push that far into OO land. There's a reason we aren't all using
: Python and Ruby by now.
Sounds to me like you're just allergic to dots.
And I don't buy the nuclear blackmail argument either. I'll start
worrying about people switching to Python and Ruby when those languages
get a clue about how natural languages work. As far as I know, there's
little notion of topics in those languages as of yet. (Though I wouldn't
be surprised if other languages eventually adopt our invocantless .foo
notation. For the price of one character, we document exactly which
functions default to $_. In Perl 5 you just have to memorize the list.)
But as I say, I'm not yet convinced $*ARGS should be the topic.
It would only be the topic outside of the main loop, and people would
wonder why .lines gives them a different answer in another location.
That's the real problem with it. So you'll probably get your wish
of some non-OO-looking syntactic sugar. Might even just be a global
multi sub that defaults to $*ARGS:
multi sub *lines (IO ?$handle = $*ARGS) {...}
multi sub *lines (Str $filename) {...}
multi sub *lines (IO @handle) {...}
multi sub *lines (Str @filenames) {...}
Then the filter call would be quite hypoallergenic:
for lines {...}
Interestingly, though, you can also call it as $fh.lines if you like.
Or even if you don't.
Larry
Re: Angle quotes and pointy brackets
On Tue, 30 Nov 2004 14:58:13 -0800, Larry Wall [EMAIL PROTECTED] wrote:
But then it's not a general iterator iterator. Plus it has the Unicode
taint...
Back to reality, another thought to weave in here is that something
like
for $iterator.each - $x {...}
might specify that there may be ordering dependencies from loop
iteration to loop iteration, whereas (since junctions are inherently
unordered) saying:
for $iterator.all - $x {...}
explicitly tells the system it can parallelize the loop without worrying
about interation between iterations.
I've been thinking about it, and this strikes me as really odd. Perl 5
is full of nice shortcuts. One of them is:
for (@array) {
which takes the place of
for (my $i = 0; $i @array; $i++) {
which is what you'd have to do in a lot of other languages. What I
mean is that Perl takes an array and makes an iterator out of it.
Sure, you probably don't think about it like that, but the behavior is
the same (who says arrays need to iterate starting at element zero?).
Java just introduced something similar in 1.5.
The odd thing is that here we are designing Perl 6, and we're trying
to take an iterator and make it into an array so that we can turn it
back into an iterator again. It seems like we should just use it as an
iterator::
for $iterator - $elem { ... }
Your message leads me to believe that
for all(1, 2, 3) - $num { ... }
is already a special case that will or can be recognized and
optimized. If so, having special behavior for an iterator shouldn't be
much more difficult (though I'm not sure of the correctness or full
ramifications of this statement).
That would have the added benefit of letting me write this:
for open($filename) or die - $line { ... }
which I like. A method could be used for retrieving the next
line/char/byte/whatever:
my $fh = open $filename or die;
my $line = $fh.next
where C.next splits on the input record separator. C.next_byte and
family could be implemented on top of that as well.
The biggest problem I see (and I may just be blind) is that
for $iterator - $x { ... }
is slightly ambiguous to the programmer, which makes me want angle
brackets back. Other syntax could be used (though we seem to be
drawing a blank there), but I don't like the idea of using a method
(see Iterator-Array-Iterator above).
I also like the idea of general iterators. Really like it. Perl 5 had
it via Ctie, but it wasn't so pretty. Supposing
class Filehandle does Iterate; # Iterate or Iterator?
we have an easy way to create new iterators. I'm not sure how useful
they would be in Perl 6 (how do iterators compare to lazy lists?), but
I can see if being useful.
For instance, perhaps a more idiomatic DBI could be written like this:
my $sth = $dbh.prepare('SELECT * FROM foo');
for $sth.execute.iter - $results { ... }
Which be even cuter like this (I think):
for iter($sth.execute) - $results { ... }
where iter creates an Iterator object that just knows to call C.next
on its argument.
Anyway, take it for what its worth. I'm aware of how ridiculous many
of the things we (that includes me) say are, but perhaps I've said
something useful.
Hoping I haven't removed all doubt of my foolishness,
--
matt diephouse
http://matt.diephouse.com
Iteration Again (was «Re: Angle quotes and pointy brackets»)
In article [EMAIL PROTECTED],
[EMAIL PROTECTED] (Brent 'Dax' Royal-Gordon) wrote:
I'm going to pull a Larry and think out
loud for a minute here. Note that I speak authoritatively here,
Noted. Or not. =)
Treating it like an array is wrong.
On the other hand, what if a filehandle *is* an array? What if you
can access it randomly and non-destructively?
I like this line of thought -- sure, arrays and iterators are
different, but they're also similar, so they ought to look similar in
at least some ways. We already think of files in a somewhat-array-
like manner (Gimme line 42 of this file) rather than mere iterators
(Get the first 41 lines of this file, throw them away, and then gimme
the next one), so why shouldn't Perl reflect that? Keeping the easy
things trivial and all...
An iterator can also be quite unlike an array (for instance a pipe,
where you can't jump back to the beginning, even inefficiently), but
I think those differences apply at a slightly higher level,
conceptually. (Or they would if we weren't forced by the language to
think of them differently at the lower level.) After all, if you
know you're dealing with a pipe, it would probably never even occur
to you to try accessing it randomly; on the other hand, if you don't
know whether your object is an array or a file or a pipe to begin
with, you're already in trouble.
But .shift looks a bit awkward. I suggest a name change for .shift
and .unshift, so that we have:
push, pop
pull, put
Hm, I like that, the parallelisms with the number of letters, and the
way they all begin with P. Plus the meanings make sense (you pull
something towards you -- that's the front end -- but when something
pops off, it goes flying away from you -- that's the back).
So now we have:
my $fh=open foo.txt;
say $fh.pull;
for $fh.pullall {
I'm not crazy about pullall. If the idea is we want to slurp up
the file right now, can't we use our flattening splatter? (for
[EMAIL PROTECTED] ...)
And what about iterators in general? Well, if we can do it to
filehandles, why not all iterators? An iterator is simply a lazy
array copy that isn't accessed randomly;
Or maybe a lazy array is just an iterator (with some extra abilities
added on). But I'm all for taking advantage of the commonalities.
-David which is related to another kind of laziness Green
Re: Angle quotes and pointy brackets
In article [EMAIL PROTECTED], [EMAIL PROTECTED] (Smylers) wrote: David Green writes: I'm not even sure what those double-quotation marks are doing -- [...] Look back at how Larry defined the guillemets: [...] So the double-quotes in there are shell-like, though I guess if you don't have a Unix background that doesn't mean much to you. Ah, of course. I read that straight in one eye and out the other. =) -David getting carried away with parallelogies that aren't quite there, but I like the new definition anyway Green
Re: Angle quotes and pointy brackets
Larry Wall wrote:
I thought so.
: I don't think I've ever used a hash slice in my life. Is there something
: wrong with me?
No, a lot of people are naturally monoindexous.
I like that word.
: * The :w splitting happens after interpolation. So
:
: « foo $bar @baz »
:
: can end up with lots of words, while
:
: « foo $bar @baz »
:
: is guaranteed to end up with three words.
:
: See the comment about 'fabulouser' above and add another 'and
: fabulouser' to the end.
I neglected to mention that the smart quoter should also recognize
pair notation and handle it.
I've been trying to get my brain round that, but I can't quite figure
out what you mean. Pair notation is, as I understand it, when you get
key = value
to construct a pair. Assuming that's me remembering correctly, then
where does the smart quoter have to deal with pair notation? Are you
considering allowing something like:
« key1 = flop key2 = floop »
Which would be
hash(key1 = flop, key2 = floop);
or am I completely off my rocker? I hope I am, because that's kind of
ugly. The only other thing I can think of is if you're just talking
about *implementing* infix:=, in which case just ignore the above
because of course the autoquoter needs to recognise its left-hand-side.
As an aside, is it possible for us to define our own autoquoting
operators? I assume it will be, but I'm feeling insecure and need
reassurance.
I neglected to mention that we also naturally get both of:
circumfix:« »
circumfix:« »
in addition to
circumfix:{'',''}
circumfix:{'«','»'}
Have to be careful with
circumfix:«{ }»
though, since {...} interpolates these days.
Yes, that would be fun... almost worth throwing out a compiler warning
for that, especially if we've still got use warnings. Something like
Warning: «{ }» creates empty list
or even
Warning: circumfix:«{ }» creates empty operator
that one could be an error in fact.
or if you're feeling really nasty
Syntax error
Because I'm sure it should be wrong to create empty circumfix operators.
Or am I too prescriptive? My inner Haskell programmer is showing through.
Re: Angle quotes and pointy brackets
Juerd wrote:
Matthew Walton skribis 2004-12-01 9:55 (+):
Yes, that would be fun... almost worth throwing out a compiler warning
for that, especially if we've still got use warnings. Something like
Warning: «{ }» creates empty list
It should generate a warning similar to the warning of interpolating an
undefined value, but with s/undefined variable/empty list/.
Yes, that would make sense.
Because I'm sure it should be wrong to create empty circumfix operators.
You have to admit that zero width circumfix operators would be VERY NEAT.
Well that depends... are you intending to write programs, or drive the
world insane?
Re: Angle quotes and pointy brackets
Matthew Walton skribis 2004-12-01 10:11 (+): Well that depends... are you intending to write programs, or drive the world insane? Yes. Juerd
Re: Angle quotes and pointy brackets
A request to everyone who wants to discuss this again: please, read the
Backticks thread. Almost everything that can be said about this subject
has already been said before. It is a huge thread, and let's not copy
everything here.
Alexey Trofimenko skribis 2004-11-30 14:34 (+0300):
but it puts big restrictions on what can be part of the name (actually,
thoose which match to ident only), so $package'$varname won't work.
I meant only that your ` can't be replacement to « » because latter allows
MUCH more freedom in key names. Actually, only space has special meaning
here.
I suggest that you re-read the Backticks thread of April this year.
Summarized in reaction to above snippet: it would not be the only place
where Perl's syntax is optimized for the most common use, but has an
alternative available. I don't recall ever having said that %hash`key
was a *replacement* for %hash«key».
so, could you be more explicit, what rules your syntax have?
I cannot be much more explicit than in referenced thread, but since you
ask specific questions, I will answer them.
$a`$b+$c`$d, is it equivalent of
$a[$b+$c][$d] or $a[$b]+$c[$d] ?
The latter. I intended whetever is seen as a string in Perl 5 $hash{key}
to be valid. In general, that is: any valid identifier (except it may
start with a digit, and optionally have a - before it).
Should you want to play with the syntax, then use Matthijs' patch for
Perl 5, which enables the backticks for hash element selection.
and I think, polymorphic treating of ` as either {} or [] adds some
overhead.. and unstability of your code.
Then have it just for hashes. I don't think it is at all true, though.
Especially in cases like $a`$b,
when compiler just can't see in compiler time, what could be contained in
$b - number or string.
I suggested deciding based on the value of the RHS once, but no longer
support that. The decision should be based on the LHS alone, and if the
LHS supports both postcircumfix:«{ }» and postcircumfix:«[ ]», then the
{} wins.
no spaces allowed, no expressions, and it is always a HASH subscript.
No expressions, but a simple atomic scalar variable should be allowed,
as is true for methods too:
$foo.bar
$foo.$bar
Re spaces, I don't see any reason to disallow them on either side.
They're allowed around . too.
Juerd
Re: Angle quotes and pointy brackets
Brent 'Dax' Royal-Gordon wrote: I like this in general. However... Larry Wall [EMAIL PROTECTED] wrote: * Since we already stole angles from iterators, «$fh» is not how you make iterators iterate. Instead we use $fh.fetch (or whatever) in scalar context, and $fh.fetch or @$fh or $fh[] or *$fh in list context. I believe you tried this one a couple years ago, and people freaked out. As an alternative, could we get a different operator for this? I propose one of: $fh - $fh» (and $fh) $fh All three have connotations of the next thing. The first one might interfere with pointy subs, though, and the last two would be whitespace-sensitive. (But it looks like that isn't a bad thing anymore...) Any other suggestions, people? ++$fh
Re: Angle quotes and pointy brackets
Austin~ On Tue, 30 Nov 2004 18:15:54 -0500, Austin Hastings [EMAIL PROTECTED] wrote: Austin Hastings wrote: Larry Wall wrote: And now, Piers is cackling madly at Matt: welcome to perl6-hightraffic! :-) Even if he wasn't cackling, I admit to feeling it. I don't even use the qx/qq/qw stuff in perl5. I always got by with . Although I must admit to liking python's C r... meaning absolutely raw string (useful for avoiding double escape problems with their regular expressions). Left me thinking it was short for regex and not raw for a little while... Matt -- Computer Science is merely the post-Turing Decline of Formal Systems Theory. -???
Re: Angle quotes and pointy brackets
AH == Austin Hastings [EMAIL PROTECTED] writes:
AH Larry Wall wrote:
* We get the cute, clean and rather more typeable
$varkey1key2[3]key3
AH No more or less typeable for me, or anyone else who can remap their
AH keyboard. I'm presuming there's something costly about {} on non-US
AH keyboards, but how much does it cost? and do those non-US perl hacks
AH use remapping already?
i think the diff between $hash and $hash{} is that autoquotes (and
only allows) single words and {} requires quote words or expressions. so
$hashfoo is the same as $hash{'foo'}. $hash{foo} is either a syntax
error or something i can't figure out (foo is a bareword which is
illegal IIRC).
* People can probably get used to reading things like:
$varkey1key2[3]key3 $varkey1key2[4]key3
AH It's just as readable as XML.
it is only for fixed token keys and who actually writes hash accesses
that deep and very often? i would assign the midlevel hashes to a scalar
and work from there if this was common code.
AH Carp.
AH Carp.
AH Carp.
main::Carp can't be found. Perhaps you forgot to use the Carp
qw(no_carping_at_larry)? :)
uri
--
Uri Guttman -- [EMAIL PROTECTED] http://www.stemsystems.com
--Perl Consulting, Stem Development, Systems Architecture, Design and Coding-
Search or Offer Perl Jobs http://jobs.perl.org
Re: Angle quotes and pointy brackets
On Tue, Nov 30, 2004 at 02:26:06PM -0800, Brent 'Dax' Royal-Gordon wrote: : Larry Wall [EMAIL PROTECTED] wrote: : * Since we already stole angles from iterators, «$fh» is not : how you make iterators iterate. Instead we use $fh.fetch (or : whatever) in scalar context, and $fh.fetch or @$fh or $fh[] : or *$fh in list context. : : I believe you tried this one a couple years ago, and people freaked : out. As an alternative, could we get a different operator for this? : I propose one of: : : $fh - : $fh» (and $fh) : $fh : : All three have connotations of the next thing. The first one might : interfere with pointy subs, though, and the last two would be : whitespace-sensitive. (But it looks like that isn't a bad thing : anymore...) In lines with the '...' ... and ... ... progressions, the following progression has a nice symmetry: $iter --#extract next (one) element from iterator $iter $iter ==#pipeline all elements (lazy) in turn from iterator $iter However, I haven't been paying a lot of attention, to the current state of affairs, so it is probably broken in some way. --
Re: Angle quotes and pointy brackets
On Tue, Nov 30, 2004 at 06:27:55PM -0500, Matt Fowles wrote: : Even if he wasn't cackling, I admit to feeling it. I don't even use : the qx/qq/qw stuff in perl5. I always got by with . : : Although I must admit to liking python's C r... meaning : absolutely raw string (useful for avoiding double escape problems with : their regular expressions). Left me thinking it was short for regex : and not raw for a little while... Actually, I was thinking about a raw option, so q:r could be it. And it might actually turn out to be useful for quoting rules if for some reason you really don't want to write an rx//. And oddly, it might end up with a qr// shorthand. So we might end up with qr:here'END' for the Perl 6 equivalent to 'END'. Larry
Re: Angle quotes and pointy brackets
On Tue, Nov 30, 2004 at 03:03:38PM -0800, Jon Ericson wrote:
: Larry Wall [EMAIL PROTECTED] writes:
:
: The p5-to-p6 translator will turn any
:
: while (handle) {...}
:
: into
:
: for @$handle {...}
:
: Including:
:
: while() {...}
:
: to
:
: for @$ {...}
:
: ?
You left out the most important phrase:
or whatever we decide is the correctest idiom.
So if, as has been pointed out, @$handle is too much role shear, then we
probably go with something like
for *$handle {...}
in which case, if there's no handle, it seems to degrade to
for * {...}
which seems amazingly something or other.
Larry
Re: Angle quotes and pointy brackets
On 11/30/04 9:54 PM, Matt Diephouse wrote: use CGI «:standard»; [...] use CGi :standard; Who is doing this? I'm just saying... use CGI ':standard'; It really ain't all that broke, is it? -John
Re: Angle quotes and pointy brackets
John Siracusa [EMAIL PROTECTED] wrote: On 11/30/04 9:54 PM, Matt Diephouse wrote: use CGI «:standard»; [...] use CGi :standard; Who is doing this? I'm just saying... use CGI ':standard'; And won't we just be doing: use CGI :standard; anyway? -- Brent 'Dax' Royal-Gordon [EMAIL PROTECTED] Perl and Parrot hacker I might be an idiot, but not a stupid one. --c.l.p.misc (name omitted to protect the foolish)
Re: Angle quotes and pointy brackets
All the cool kids are thinking aloud these days. Why not jump on the bandwagon? Larry Wall writes: * We get the cute, clean and rather more typeable $varkey1key2[3]key3 It looks like if you shook that up and down a bit, it would break in half. I wonder what would happen if we made a little smarter, as in: * foo ; bar acts as a multidimensional subscript (* but what for @array = foo ; bar?) * +42 returns a number instead of a string. Then: $varfoo ; bar ; +3 ; baz Which is certainly less noisy than the kitkat above. Problems: * -foo is common for options; don't want to force a number. Then again, you don't see -6 as an option too often. * Doesn't solve anything in the practical scenario where some of your keys are not constant. But we'd, of course, do the same thing to . However, there's a problem with : it doesn't generalize to non-string keys (since $foo can reasonably only stringify). That is: $varfoo ; $bar ; +3 Doesn't work if $bar is something unstringly that happens to be the key type of the second dimension. Not to mention that if we allowed semicolon, would be the common one again, and we'd be in for another switcheroo. Anyway, I think there's something wrong with: $varfoobar[3]baz It doesn't hold together visually. This might have some relation to the other problem on my mind: the difference between $, @, and % these days. The rest of the proposal is pretty snazzy, though. Luke
Re: Angle quotes and pointy brackets
On Tue, 30 Nov 2004 19:10:48 -0800, Brent 'Dax' Royal-Gordon [EMAIL PROTECTED] wrote: John Siracusa [EMAIL PROTECTED] wrote: Who is doing this? I'm just saying... use CGI ':standard'; I normally use qw// when use-ing. *shrug* And won't we just be doing: use CGI :standard; anyway? Yeah, we will; I forgot. :-) I don't use Perl 6 very often (yet). -- matt diephouse http://matt.diephouse.com
Re: Angle quotes and pointy brackets
On Tue, 30 Nov 2004 19:10:48 -0800, Brent 'Dax' Royal-Gordon [EMAIL PROTECTED] wrote: John Siracusa [EMAIL PROTECTED] wrote: On 11/30/04 9:54 PM, Matt Diephouse wrote: use CGI «:standard»; [...] use CGi :standard; Who is doing this? I'm just saying... use CGI ':standard'; And won't we just be doing: use CGI :standard; anyway? Indeed. Also, someone *ahem* will make the following work, with or without the C. %hash.:foo:bar:baz = 10; Ashley Winters
Re: Angle quotes and pointy brackets
John Siracusa writes:
Call me crazy, but at this point I'm prone to stick with what I've done in
Perl 5 for years:
$var{'key1'}{'key2'}[3]{'key3'}
In which case do that, since it'll still work in Perl 6.
Actually, it works 'better' in Perl 6, since it doesn't mislead in any
way.
I've encountered several Perl programmers who feel 'uneasy' about the
auto-quoting rules of hash keys, so choose not to bother with them and
put all the quotes in as you do above. The trouble with that in Perl 5
is that it gives the impression that the quotes are actually doing
something. That then leads to bugs like writing:
$log{time} = $msg;
where because the programmer has explicitly _not_ used quotes and want
to invoke a function rather than use the literal string time. But
because in fact the quotes weren't doing anything, removing them doesn't
change anything.
That awkwardness is fixed in Perl 6: because the quotes _are_ now needed
with the C $hash{'key'} syntax when you want to quote, you can not
have quotes when you don't want to quote (and Perl will automatically
not quote it for you!).
So life is better for people who like writing hash subscripts as you do.
But for those who like autoquoting, there's now a different syntax, one
that doesn't interfere with the above syntax at all. You don't have to
use it if you don't want to, and everybody's happy!
Smylers
Re: Backticks (was: Angle quotes and pointy brackets)
Juerd writes: Luke Palmer skribis 2004-11-29 16:10 (-0700): http://groups.google.com/groups?selm=20040420175551.GA16162%40wall.orgrnum=1clarify It says that backticks won't be used at all in Perl 6. That's (the) one key of the keyboard that we're leaving to user-definition. It says that, but after saying Leaving aside the use of C`` as a term And that use of backticks is what this subthread appears to be about. As I interpret it, backsticks for qx, unless elsewhere declared gone, are still there. Sorry, I misread. Luke
Re: Angle quotes and pointy brackets
Matthew Walton wrote:
James Mastros wrote:
Larry Wall wrote:
On Fri, Nov 26, 2004 at 07:32:58AM +0300, Alexey Trofimenko wrote:
: ah, I forget, how could I do qx'echo $VAR' in Perl6? something like
: qx:noparse 'echo $VAR' ?
I think we need two more adverbs that add the special features of qx
and qw,
so that you could write that:
q:x/echo $VAR/
where ordinary qx/$cmd/ is short for
qq:x/$cmd/
I think I'd like that much better if we consider execution and
word-splitting to be the primary operations, and interpolation and
noninterpolation the adverbial modifiers then the other way around,
making that qx:q/echo $VAR/ or qx:qq/$cmd/.
especially because adverbs are meant to say how to do rather than what
to do, aren't they?
OTOH, I expect backticks to be rare enough that I wouldn't mind writing
use Spawn 'spawn';
spawn :capture :wait ($cmd);
spawn :capture :wait ('echo $VAR');
Although I'm masochistic enough that I don't mind the idea of always
having to do execution with qx//, qx:q// or qx:qq// (running with other
suggestions, I'd guess that would be non-interpolating execution, then
the same again more explicitly, then interpolating execution) but I do
like the idea of spawn.
hm.. qx:q// qx:qq//
...compare with:
qx q// qx qq//
so there's no need in adverbs. But we have no need in qx either. Why to
introduce (or REintroduce) something if we have something similar already?
$captured = system :capture q/cmd../;
or maybe even:
(code=$code, out=$captured, err=$err) = system qq/cmd/;
or maybe even(!)
$captured = slurp qq/$cmd |/;
Kind of removes the idea of pulling in the output of other programs as a
fundamental part of the language though, for that it's nice to have an
executing, capturing quote. Perhaps an adverb to qx that makes it behave
like system() - I don't think it'd be a good idea to provide one that
makes it behave like exec(), although perhaps other people do.
I haven't that long unix background, and spawning processes is a very
*fat* operation for me.. maybe after year or two I'll change my point of
view, but for now I would be pretty happy with a 'slurp' variant. IMHO,
spawning processes has nothing to do with other quoters, and perl already
went far away from shells.
but talking about oneliners and short shell-like scripts, where `` is
pretty useful.. hm.. things good for oneliners are rarely as good for
larger programs, and vice versa. Of course, Perl5 proves opposite, but
Perl6 tends to be a little more verbose, and even in Perl5 we use quite
different toolbox and style for mentioned above. Why not to make an
average sized module of various shortcut grammars, with a very short
name (x, f.e.), with defaults to export :all, so we could just do
perl -Mx -e 'print `echo this is a perl5qx`'
even if `` would be taken for something more useful in Perl6,
and still be able to import only something useful for our larger program
with
use x qw/:perl5qx/;
Re: Angle quotes and pointy brackets
Juerd [EMAIL PROTECTED] wrote:
but talking about oneliners and short shell-like scripts, where `` is
pretty useful.. hm.. things good for oneliners are rarely as good for
larger programs, and vice versa. Of course, Perl5 proves opposite, but
Perl6 tends to be a little more verbose, and even in Perl5 we use quite
different toolbox and style for mentioned above. Why not to make an
average sized module of various shortcut grammars, with a very short
name (x, f.e.), with defaults to export :all, so we could just do
perl -Mx -e 'print `echo this is a perl5qx`'
For oneliners, I think I'd appreciate using -o for that. The module
itself can be Perl::OneLiner.
module e {
module *::Main {
# Or whatever we'd need to do to switch to the top-level Main
close $*CODE;# if there is such a thing
no strict;
no warnings;
my macro circumfix:` ` (String $cmd)
is parsed(/ [^`\\]* [ \\ . [^`\\]*: ] * /) {
{ run :capture $cmd }
}
use File::Copy qw(mv cp);
...
# I do hope we get something better than #line.
eval #line 1 '-me'\n ~ @ARGS.shift;
}
}
perl -me 'say This is my one-liner!'
One-liners with no specific support in the core--and it's different
from Perl 5, so we can detect old one-liners. How's that for
orthagonal?
--
Brent 'Dax' Royal-Gordon [EMAIL PROTECTED]
Perl and Parrot hacker
I might be an idiot, but not a stupid one.
--c.l.p.misc (name omitted to protect the foolish)
Re: Angle quotes and pointy brackets
On Fri, 26 Nov 2004 09:33:49 -0800, Larry Wall [EMAIL PROTECTED] wrote:
On Fri, Nov 26, 2004 at 07:32:58AM +0300, Alexey Trofimenko wrote:
: I notice that in Perl6 thoose funny and could be much more common
: than other paired brackets. And some people likes how they look, but
: nobody likes the fact that there's no (and won't!) be a consistent way
to : type them in different applications, wether it's hard or easy.
...
: We also have another ascii pair, and . maybe they could be better
: than and ?:) i'm not that farseeing, but isn't problem of :
distinguishing as a bracket and as an comparison operator no harder
: than distinguishing as bracket and as part of heredoc?..
It would get very confusing visually, even if the computer could sort it
out:
@a = @b
@a = @b
But there are some things that would be completely ambiguous:
%hashfoobar
%hashfoobaz()
I not meant to replace it everywhere. But problem still exists.
I know about only four uses of and . Tell me if there's more?
1) hyperoperators;
@a = @b * @c @a.method
@a = @b * @c @a.method
(and, of course, mentioned in the past supercool 7-chars =:=
operator!)
hm.. IMO, hyperoperations are fat enough to be fat even in code. I
wonder only if whitespace allowed there:
@a = @b * @c @a .method
2) qw//-like construct;
@array = foo bar baz
@array = foo bar baz
@array = qwfoo bar baz
once again, there's nothing wrong. Although, using just foo bar baz
would confuse Perl6 no more than globs and filehandles confuses Perl5.
want an operator/want a term rule applies here.
3) pair(adverb) value quoting;
myfunc :foobar :barbaz
myfunc :arrayvalue1 value2 value3
myfunc :foobar :barbaz # this certainly suck
myfunc :foo(bar) :bar(baz) # I'm going to use that if it works(?).
# still this suck less:
myfunc :array value1 value2 value3
# ..than:
myfunc :array(value1, value2, value3)
but replacement of with plain here is a no-problem:
myfunc :foobar :barbaz :arrayvalue1 value2 value3
after you type :foobar only three times, you'll acquire internal alarm
on constructs like
myfunc :foobar :bar10;
which are rather obfuscating already.
IMHO, mandatory whitespace between :bar and 10 here won't make anybody
sick.
I wonder how many people would like to write it
myfunc:foobar:bar10;
4) hash subscripting;
that's a real pain.
rather cute
$varkey1key2[3]key3
suddenly becomes an ugly monster:
$varkey1key2[3]key3
of course we could write:
$var{'key1'}{'key2'}[3]{'key3'}
and I would prefer this one to previous variant..
but it adds noise too. and it prevent us to logicaly recognize 'key1' and
'key2' not as strings but as something more like struct elements, like we
got used in perl5
When I look at this
$varkey1key2[3]key3
then I think that it's a *very* cute, nice, and clean syntax... I really
like it!
(and I would sacrifice something for that to happen, if I would be Larry
:) )
but there's a problem for people and parser too. is a comparison
*operator* and hash subscript is *operator* too, and there's no way to
distinguish them at all. Term rule won't help here.
+ and + for comparison is plain sickness, of course. But we have some
whitespace rules already. One of them is that subscripts shouldn't have
whitespace to the left of them. We could add one more - to always PUT
whitespace before comparison. so
$afoo.. is a start of subscript and
$a foo.. is always a comparison.
Personally I'm not lazy to put spaces because of my little Forth
experience.
but I don't want to be lynched by mad horde of programmers in white robes,
who will discover that
while $a$b {...}
for qwa b c {...}
and even
foo()bar()...
do something completelly wrong, and parser just unable to catch this..
(hm.. bad examples.. maybe it could be made able to?)
*sigh.. I'll write my own grammar:) I only afraid that it would take a
half of all my remaining lifetime (because of addiction)
But I'll return to topic.
I've seen proposal by Juerd, somewhere it this thread, to use `` for
autoquoting subscripting.
but proposed
%hash`foo`bar`$foo`0`$bar=0
not going to work
delimiters should have corresponding closing character, so it should be
something like
%hash`foo``bar`{$foo}[0]{$bar}=0
or it would be *much* worse for parser than .
actually, (countrary to [] and {} which could have arbitrary complex
nested expressions in it) autoquoting subscript shouldn't neccessarily
be a paired string. Any character could be used for it without any
ambiguity. Even perl4 style ' or even
Same with :pairs
%hashkeyanotherkey[1]=0
%hash'key''anotherkey'[1]=0
:keyvalue
:key'value'
ah, using here would cause difficulties to interpolation of hello,
$world
so what about ' or ` (or whatever you could imagine)?
P.S. I also considered shorcuts like
$varkey1key2key3[1] # but that not going to remove MUCH of
linenoise.
or
$var.key1key2[1].key3 #
Re: Angle quotes and pointy brackets
Juerd writes: For oneliners, I think I'd appreciate using -o for that. The module itself can be Perl::OneLiner. Things the module could do: * disable the default strict The C-e flag indicating the one-liner disables Cstrict anyway. Smylers
Re: Angle quotes and pointy brackets
On Sat, 27 Nov 2004 10:28:28 -0800, Larry Wall [EMAIL PROTECTED] wrote: On Fri, Nov 26, 2004 at 02:10:06PM -0800, Larry Wall wrote: : I know everone has their reflexes tuned to type qw currently, but : how many of you Gentle Readers would feel blighted if we turned it : into q:w instead? Of course, if we wanted to really drive it into the ground, we could turn qq// into q:q//, and then there's only one quoter. I'm sure if we tried hard enough we could find someone this appeals to. You don't even have to look very far. This seems like a decent idea to me (although I won't be sad if it doesn't happen). We also haven't quite detangled the backslash options. Seems there are four levels of support (using \/ to stand for any terminator character): 0) none # '' default 1) \\ and \/# q// default 2) list # (nothing builtin) 3) all # qq// default We need some way of specifying level 0 for a non-heredoc. We could turn q// into that, I suppose. If we did, either we'd have to make '' the same, or let it differ from q//, neither of which quite appeals to me, but I might let myself be argued into one of them or the other. Actually, I'd like to see '' be a simple, completely raw quoting construct. But if we don't do that, we might be able to take a page out of C#'s book with @ as the short form of the raw quoting construct. (Or something like that--I suspect C# picked @ because it's otherwise unused.) Actually, if we do something else with backticks, we can steal backticks for totally raw quoting... I'm open to other ideas, though we must remind ourselves that this is all very bike-sheddish. Oh, I vote for blue paint on that bike shed. -- Brent 'Dax' Royal-Gordon [EMAIL PROTECTED] Perl and Parrot hacker There is no cabal.
Re: Angle quotes and pointy brackets
James Mastros wrote:
Larry Wall wrote:
On Fri, Nov 26, 2004 at 07:32:58AM +0300, Alexey Trofimenko wrote:
: ah, I forget, how could I do qx'echo $VAR' in Perl6? something like
: qx:noparse 'echo $VAR' ?
I think we need two more adverbs that add the special features of qx
and qw,
so that you could write that:
q:x/echo $VAR/
where ordinary qx/$cmd/ is short for
qq:x/$cmd/
I think I'd like that much better if we consider execution and
word-splitting to be the primary operations, and interpolation and
noninterpolation the adverbial modifiers then the other way around,
making that qx:q/echo $VAR/ or qx:qq/$cmd/. OTOH, I expect backticks to
be rare enough that I wouldn't mind writing
use Spawn 'spawn';
spawn :capture :wait ($cmd);
spawn :capture :wait ('echo $VAR');
Much more clear, saves ` for other things, and allows for easy
specification of the many adverbs of spawn (weather it returns the
return status, the PID/FH set object, or output, if it waits right
there, or runs in the background (and makes the return value lazy), if
it replaces the current process (exec)...
I'd quite like that. Although I think spawn should be a builtin rather
than in a module, if it was in the core, and we were getting rid of
backticks.
Although I'm masochistic enough that I don't mind the idea of always
having to do execution with qx//, qx:q// or qx:qq// (running with other
suggestions, I'd guess that would be non-interpolating execution, then
the same again more explicitly, then interpolating execution) but I do
like the idea of spawn.
Kind of removes the idea of pulling in the output of other programs as a
fundamental part of the language though, for that it's nice to have an
executing, capturing quote. Perhaps an adverb to qx that makes it behave
like system() - I don't think it'd be a good idea to provide one that
makes it behave like exec(), although perhaps other people do.
qx:r/$cmd/
qx:s/$cmd/ # both of these give back return codes? Which one!
But then
qx:r:qq// might be messy.
Or even
qx:exitcode:interpolate//
Ouch.
This isn't very coherent, I'm just thinking out loud based on what other
people have said that I like.
But there are some things that would be completely ambiguous:
%hashfoobar
Bracketing operator.
%hashfoobaz()
Very long bracket operator, which quite likely has a syntax error
directly after it.
But might not have... there's a chance that could slip through, and I
don't like that for some reason.
: or maybe even we could see consistant to go after + + and alike,
and : make old and written as + and + (and then lt and gt
suddenly could : become ~ and ~ :)
I think people would rise up and slay us if we did that. We're already
getting sufficiently risen up and slain over Perl 6.
Could be worse. They could rise from the grave and eat us!
Who says they won't?
Well, yes, but sometimes the weights change over time, so it doesn't
hurt (much) to reevaluate occasionally. But in this case, I think I
still prefer to attach the exotic characters to the exotic behaviors,
and leave the angles with their customary uses.
...of which they have plenty already. Backtick has exactly one, and not
an often-used one at that... I'm fine with axing it. Of course, there
are a lot more people in the world then just me.
I'm fine with it too. I use it a fair bit but I think it's important to
have a very clear mark where you're going to an external program
Re: Angle quotes and pointy brackets
On Sat, Nov 27, 2004 at 08:21:06PM +0100, Juerd wrote:
James Mastros skribis 2004-11-27 11:36 (+0100):
Much more clear, saves ` for other things
I like the idea. But as a earlier thread showed, people find backticks
ugly. Strangely enough, only when used for something other than
readpipe.
The idea of being able to write
%hash{'foo'}{'bar'}{$foo}[0]{$bar}
as
%hash`foo`bar`$foo`0`$bar
still works very well for me. At least on all keyboards that I own, it
is easier to type. And in all fonts that I use for terminals (that'd be
only misc-fixed and 80x24 text terminals), it improves legibility too.
Doesn't that cause ambiguity between:
%hash{'foo'}{'bar'}{$foo}[0]{$bar}
and
%hash{'foo'}{'bar'}{$foo}{0}{$bar}
^ ^ hash instead of subscript
--
Re: Angle quotes and pointy brackets
On Sun, Nov 28, 2004 at 12:24:08PM -0500, John Macdonald wrote:
On Sat, Nov 27, 2004 at 08:21:06PM +0100, Juerd wrote:
James Mastros skribis 2004-11-27 11:36 (+0100):
Much more clear, saves ` for other things
I like the idea. But as a earlier thread showed, people find backticks
ugly. Strangely enough, only when used for something other than
readpipe.
The idea of being able to write
%hash{'foo'}{'bar'}{$foo}[0]{$bar}
as
%hash`foo`bar`$foo`0`$bar
still works very well for me. At least on all keyboards that I own, it
is easier to type. And in all fonts that I use for terminals (that'd be
only misc-fixed and 80x24 text terminals), it improves legibility too.
Doesn't that cause ambiguity between:
%hash{'foo'}{'bar'}{$foo}[0]{$bar}
and
%hash{'foo'}{'bar'}{$foo}{0}{$bar}
^ ^ hash instead of subscript
Hmm, I guess it is usually not ambiguous, only when it is
causing auto-vivification of the hash-or-array with `0` is
there an ambiguity between whether that means [0] and {'0'}.
--
Re: Angle quotes and pointy brackets and heredocs
On Fri, Nov 26, 2004 at 07:32:58AM +0300, Alexey Trofimenko wrote:
I notice that in Perl6 thoose funny « and » could be much more common
than other paired brackets. And some people likes how they look, but
nobody likes fact that there's no (and won't!) be a consistent way to type
them in different applications, wether it's hard or easy.
But to swap «» with [] or {} could be real shock for major part of
people..
We also have another ascii pair, and . maybe they could be better than
« and » ?:) i'm not that farseeing, but isn't problem of distinguishing
as a bracket and as an comparison operator no harder than distinguishing
as bracket and as part of heredoc?..
Speaking of heredocs.
Are they really common enough to merit a two char, absolutely no
whitespace after it lexical? Especially one that looks a lot like the
left bitshift operator, as well as an ASCII version of a Unicode quoting
and splitting character?
What if instead, we add a different adverb to q// and qq//? something
like :h. That way people can mix and match all the quoting option they
want, and we remove some annoying requirements about when you can and
cannot have /\s+/ in your code.
P5:
print END, done.\n;
line 1
line 2
END
P6:
say qq:h/END/, done.;
line 1
line 2
END
As for the topic being discussed,
Since and are now full class quote-like thingies in P6REs, much to
the chagrin of those of us who parse html on a regular basis, using them
as such in the rest of P6 makes sense as well. Parsing should not be
hindered since one would occur in operator context, and the other in
expression context.
-- Rod Adams
Re: Angle quotes and pointy brackets
On Fri, Nov 26, 2004 at 07:32:58AM +0300, Alexey Trofimenko wrote:
: ah, I forget, how could I do qx'echo $VAR' in Perl6? something like
: qx:noparse 'echo $VAR' ?
Hmm, well, with the currently defined adverbs you'd have to say
qx:s(0)'echo $VAR'
but that doesn't give you protection from other kinds of interpolation.
I think we need two more adverbs that add the special features of qx and qw,
so that you could write that:
q:x/echo $VAR/
where ordinary qx/$cmd/ is short for
qq:x/$cmd/
Likewise a qw/a b/ is short for
q:w/a b/
: (Note: I like thoose adverbs.. I could imagine that in Perl6 if you want
: to have something done in some_other_way, you just should insert
: :some_other_way adverb, and that is! perl will DWIM happily :)
Well, that's perhaps a bit underspecified from the computer's point of view.
: I notice that in Perl6 thoose funny « and » could be much more common
: than other paired brackets. And some people likes how they look, but
: nobody likes fact that there's no (and won't!) be a consistent way to type
: them in different applications, wether it's hard or easy.
:
: But to swap «» with [] or {} could be real shock for major part of
: people..
: We also have another ascii pair, and . maybe they could be better than
: « and » ?:) i'm not that farseeing, but isn't problem of distinguishing
: as a bracket and as an comparison operator no harder than distinguishing
: as bracket and as part of heredoc?..
It would get very confusing visually, even if the computer could sort it out:
@a = @b
@a = @b
But there are some things that would be completely ambiguous:
%hashfoobar
%hashfoobaz()
: or maybe even we could see consistant to go after + + and alike, and
: make old and written as + and + (and then lt and gt suddenly could
: become ~ and ~ :)
I think people would rise up and slay us if we did that. We're already
getting sufficiently risen up and slain over Perl 6.
: But I certain, Larry already weighted exact that solution years ago..
Well, yes, but sometimes the weights change over time, so it doesn't
hurt (much) to reevaluate occasionally. But in this case, I think I
still prefer to attach the exotic characters to the exotic behaviors,
and leave the angles with their customary uses.
: P.S. If you have an urgent need to throw spoiled eggs at me, consider all
: above as very late or very early fools day joke.. or you could try, but
: i've never heard about ballistic transcontinental eggs.
If you're a White Russian I suppose the yolk is on me.
Larry
Re: Angle quotes and pointy brackets
Larry Wall skribis 2004-11-26 9:33 (-0800): but that doesn't give you protection from other kinds of interpolation. I think we need two more adverbs that add the special features of qx and qw, so that you could write that: q:x/echo $VAR/ where ordinary qx/$cmd/ is short for qq:x/$cmd/ Likewise a qw/a b/ is short for q:w/a b/ With x and w as adverbs to q and qq, are qx and qw still worth keeping? It's only one character less, qx isn't used terribly often and qw will probably be written mostly as anyway. And perhaps qq:x is a bit too dangerous. Suppose someone meant to type qq:z[$foo] (where z is a defined adverb that does something useful to the return value, but has no side effects) and mistypes it as qq:x[$foo]. Instant hard-to-spot security danger. Juerd
Angle quotes and pointy brackets
As we now know, in many situations, and « mean the same thing. In exactly those situations, the same is true for and ». However, sometimes, « cannot be used where can. Here-docs are an example. «» (or , if you wish) quotes. I am assuming that «» is a shorthand for qw«», except where special syntax is used with hash slices and :-pairs, just like //, which is short for m//, for qq, etcetera. But as « foo bar » and foo bar are the same thing, I wonder what qw foo bar means. Is that qw/ foo bar / or is that qw/foo bar/? And is this consistent with other operators, i.e. rx«» versus rx? Another question comes to mind as I am typing this message. Can « and be used together, or does « always need » and need ? If a matching pair is required, then does the same hold true for vector ops with anqle quotes on both sides (i.e. is that seen as a quoted operator, or as an operator that happens to have two vectorizing symbols)? One last question for now: how hard will it be to implement a grammar with certain not otherwise specified language features *removed*? Juerd
Re: Angle quotes and pointy brackets
Juerd writes: As we now know, in many situations, and « mean the same thing. In exactly those situations, the same is true for and ». However, sometimes, « cannot be used where can. Here-docs are an example. Why can't « be used for here-docs? I thought Larry had said they were completely interchangeable. But as « foo bar » and foo bar are the same thing, I wonder what qw foo bar means. Is that qw/ foo bar / or is that qw/foo bar/? I'd hope it's the former -- that is, that « can be substituted for anywhere that is a single operator, not just somewhere that those two characters happen to be adjacent to each other in the source, and » likewise. Otherwise you could have ridiculous things like: mfoo0 which parses as: m/foo/ 0 being written as: mfoo»0 And that's blatantly of no use to anybody. Smylers
Re: Angle quotes and pointy brackets
On Thu, Nov 25, 2004 at 09:55:54PM +0100, Juerd wrote:
: As we now know, in many situations, and « mean the same thing. In
: exactly those situations, the same is true for and ». However,
: sometimes, « cannot be used where can. Here-docs are an example.
:
: «» (or , if you wish) quotes. I am assuming that «» is a shorthand
: for qw«», except where special syntax is used with hash slices and
: :-pairs, just like //, which is short for m//, for qq, etcetera.
Hmm, I would say that is short for qq//, not qq. Quote characters
lose their identity when used with generalized quotes. (I realize this
is not always true with Perl 5, but that can be construed as a mistake.)
So «» is not really short for qw«» unless you take the delimiters of the
latter construct as simple characters without any «» baggage, including
the need to have a workaround. So I'd rather say «» is short for qw//.
: But as « foo bar » and foo bar are the same thing, I wonder what
: qw foo bar means. Is that qw/ foo bar / or is that qw/foo bar/?
: And is this consistent with other operators, i.e. rx«» versus rx?
It means qw/ foo bar/, and yes, that's consistent.
: Another question comes to mind as I am typing this message. Can « and
: be used together, or does « always need » and need ? If a matching
: pair is required, then does the same hold true for vector ops with anqle
: quotes on both sides (i.e. is that seen as a quoted operator, or as an
: operator that happens to have two vectorizing symbols)?
I don't see that it's terribly important either to allow that or to
disallow it. I do think we should discourage asymmetry, but I can well
imagine that someone who doesn't have easy «» access might end up replacing
one end without replacing the other. It should be easy for someone in
this fix to translate the line to the «» form. Perhaps perl itself ought
to offer to do the translation for you. Basically, the sooner we can get
code into a canonical form, the less trouble we'll have overall.
This approach doesn't help the person who can't even *display* «», but
that problem will be solved before the input problem is. For instance,
PerlMonks has no problem displaying «», but I haven't a clue how to type
it into my browser yet.
Some people might actually prefer to have the form illegal, not because
they don't want to type it in that way, but because they want to be forced
to translate to «» before the semi-bogus forms enter The Record.
: One last question for now: how hard will it be to implement a grammar
: with certain not otherwise specified language features *removed*?
So you want to violate Liskov substitutability on grammars, eh? :-)
While one can certainly redefine rule methods to pitch a fit if called,
the real way you cut down the language is by not referring to those
rules in the first place from elsewhere. Which means you have to override
those referring rules, after which it almost doesn't matter if the
previously referred to rules are somehow cancelled or not.
The other part of it is that some of the constructs are catalogued in
hashes and arrays rather than in rule alternatives. When you derive
a grammar you can certainly copy over a part of the hash or array and
leave out other parts. These hashes and arrays are loaded up in the
first place via the various syntactic categories we go on about. So
maybe we have some way of cancelling syntax.
BEGIN { undef circumfix:« »; }
or maybe even:
my macro circumfix:« » is gone;
That would have the effect of removing the '' key from the term hash,
or for a lexical declaration, making a copy of the term hash without
that key, so that when we hit the end of this lexical scope. we can
restore the old hash.
Larry
Re: Angle quotes and pointy brackets
Larry Wall skribis 2004-11-25 13:45 (-0800):
Hmm, I would say that is short for qq//, not qq. Quote characters
lose their identity when used with generalized quotes. (I realize this
is not always true with Perl 5, but that can be construed as a mistake.)
So «» is not really short for qw«» unless you take the delimiters of the
latter construct as simple characters without any «» baggage, including
the need to have a workaround. So I'd rather say «» is short for qw//.
I'm happy to read this. Perl 5's semantics with qx|m|qr|s and ''
probably made me translate to qq instead of qq//, or qq{} as perlop
lists it.
: But as « foo bar » and foo bar are the same thing, I wonder what
: qw foo bar means. Is that qw/ foo bar / or is that qw/foo bar/?
: And is this consistent with other operators, i.e. rx«» versus rx?
It means qw/ foo bar/, and yes, that's consistent.
That's a relief :)
This approach doesn't help the person who can't even *display* «», but
that problem will be solved before the input problem is. For instance,
PerlMonks has no problem displaying «», but I haven't a clue how to type
it into my browser yet.
Should you happen to use X with the Xkb extension, it is a matter of
assigning a key to Multi_key and then typing Multi_key .
I have assigned my rightmost Windows key (the Menu key) with:
xmodmap -e keysym Menu = Multi_key
So you want to violate Liskov substitutability on grammars, eh? :-)
I'd even violate gravity, if I could!
While one can certainly redefine rule methods to pitch a fit if called,
the real way you cut down the language is by not referring to those
rules in the first place from elsewhere. Which means you have to override
those referring rules, after which it almost doesn't matter if the
previously referred to rules are somehow cancelled or not.
I was afraid that that'd be the answer.
The other part of it is that some of the constructs are catalogued in
hashes and arrays rather than in rule alternatives. When you derive
a grammar you can certainly copy over a part of the hash or array and
leave out other parts. These hashes and arrays are loaded up in the
first place via the various syntactic categories we go on about. So
maybe we have some way of cancelling syntax.
That's better news :)
BEGIN { undef circumfix:« »; }
But if mixed « is allowed, isn't that «»syntax error? Or did I
misinterpret the answer re mixing them?
my macro circumfix:« » is gone;
Perhaps is gone is a bit too easy for something that shouldn't be
done.
Juerd
Re: Angle quotes and pointy brackets
Larry Wall writes: PerlMonks has no problem displaying «», but I haven't a clue how to type it into my browser yet. If your browser is using Gnome then holding down Ctrl+Shift while typing AB (for «) or BB (for ») might work. (This is also working for me typing this in 'Vim' in a 'Gnome Terminal', but isn't as nice as the 'Vim' digraphs.) Smylers
Re: Angle quotes and pointy brackets
On Thu, 25 Nov 2004 13:45:51 -0800, Larry Wall [EMAIL PROTECTED] wrote:
...
Hmm, I would say that is short for qq//, not qq. Quote characters
lose their identity when used with generalized quotes. (I realize this
is not always true with Perl 5, but that can be construed as a mistake.)
So is not really short for qw unless you take the delimiters of the
latter construct as simple characters without any baggage, including
the need to have a workaround. So I'd rather say is short for
qw//.
...
ah, I forget, how could I do qx'echo $VAR' in Perl6? something like
qx:noparse 'echo $VAR' ?
(Note: I like thoose adverbs.. I could imagine that in Perl6 if you want
to have something done in some_other_way, you just should insert
:some_other_way adverb, and that is! perl will DWIM happily :)
...
This approach doesn't help the person who can't even *display* , but
that problem will be solved before the input problem is. For instance,
PerlMonks has no problem displaying , but I haven't a clue how to type
it into my browser yet.
...
I notice that in Perl6 thoose funny and could be much more common than
other paired brackets. And some people likes how they look, but nobody
likes fact that there's no (and won't!) be a consistent way to type them
in different applications, wether it's hard or easy.
But to swap with [] or {} could be real shock for major part of people..
We also have another ascii pair, and . maybe they could be better than
and ?:) i'm not that farseeing, but isn't problem of distinguishing
as a bracket and as an comparison operator no harder than distinguishing
as bracket and as part of heredoc?..
or maybe even we could see consistant to go after + + and alike, and
make old and written as + and + (and then lt and gt suddenly could
become ~ and ~ :)
But I certain, Larry already weighted exact that solution years ago..
P.S. If you have an urgent need to throw spoiled eggs at me, consider all
above as very late or very early fools day joke.. or you could try, but
i've never heard about ballistic transcontinental eggs.
