Re: Hoping that Params::Validate is not needed in Perl6
On Wed, Aug 17, 2005 at 23:43:43 -0500, Dave Rolsky wrote: But I'd really like to get this stuff done at compile time wherever possible. If I write this: validate( credit_card_number: $number ); it should blow up at compile time, right? So should MMD: The type signatures are rigid, and the moment things get closed (no more MMD alternatives are possible), if your dispatches don't have any MMD candiates it's just as much a type error as a normal sub with a bad type. -- () Yuval Kogman [EMAIL PROTECTED] 0xEBD27418 perl hacker /\ kung foo master: *shu*rik*en*sh*u*rik*en*s*hur*i*ke*n*: neeyah pgpT33LKABXOy.pgp Description: PGP signature
Re: Time::Local
Well, right now one of the great things about looking at the wall to read the clock and see the time, is that you know that based on the time of day and the time of year, and where you are, roughly how far through the actual solar day it is. It's crude, but useful. Just ask a Dairy Farmer. Does the Dairy Farmer need time with seconds precision? Would he know his longitude and how to make correction to the time? (If he is a person, wouldn't it be easier for him just to buy GPS?) Of course feel free to consider this all worthless heckling, given the lack of time I've been putting towards an implementation of all this ;). Sam. Same here. Maybe this lengthy discussion isn't really that useful. I think it's about defaults, but Perl6 will have packages -- so everyone not content with the default handling of time will be able to override it. Or maybe there could be a pragma (`no leapseconds`?). Or maybe there could be a package on CP6AN named Time::Leapseconds::Data. Related question: is it possible to specify validity of a package? Something along the lines this package starts to be deprecated/imprecise/outdated after 2007. braňo tichý
Re: my $pi is constant = 3;
--
Mark Biggar
[EMAIL PROTECTED]
[EMAIL PROTECTED]
[EMAIL PROTECTED] On Wed, Aug 17, 2005 at 08:47:18AM -0700, Larry Wall wrote:
: That could be made to work by defining constant to mean you can assign
: to it if it's undefined. But then it gets a little harder to reason
: about it if $pi can later become undefined. I suppose we could
: disallow undefine($pi) though.
If you can assign it when it contains an undefined value, bad
things happen:
sub f ($x is readonly) { $x = 10 }
my $a; f($a);
Compare this with:
my $x is readonly;
$x = 10;
If it is defined as bound to a immutable value cell, both cases
above would fail, which is imho the easiest to explain.
Not only that, but what if what I want is a named constnat undef value?
On Wed, Aug 17, 2005 at 08:47:18AM -0700, Larry Wall wrote:
: That could be made to work by defining constant to mean you can assign
: to it if it's undefined. But then it gets a little harder to reason
: about it if $pi can later become undefined. I suppose we could
: disallow undefine($pi) though.
If you can assign it when it contains an undefined value, bad
things happen:
sub f ($x is readonly) { $x = 10 }
my $a; f($a);
Compare this with:
my $x is readonly;
$x = 10;
If it is defined as bound to a immutable value cell, both cases
above would fail, which is imho the easiest to explain.
You could still reason about it if you can determine what the initial
value is going to be. But certainly that's not a guarantee, which
is one of the reasons we're now calling this write/bind-once behavior
readonly and moving true constants to a separate declarator:
my $pi is readonly;
$pi = 3;
The question remains, whether you can bind the readonliness away:
my $pi is readonly; # undef at this point
my $e is rw = 2.7;
$pi := $e;
$pi = 9;
I can argue both sides -- rebindable is easier to implement, but
non-rebindable is perhaps more intuitive.
Thanks,
/Autrijus/
RE: Ambiguity of parsing numbers with underscores/methods
Larry Wall wrote: Yes, that's a convenient escape. But really, arguments from principle aside, the underlying question is what someone will see if they look at 1.e5, and I suspect most people will see a number with an exponent. This is a spot where Ruby violates Least Surprise, at least for people who aren't used to seeing methods hanging off of literals. To the original point, I have to seriously question the usefulness of invoking ambiguously named methods on numeric literals... 1e5 # number 1.0e5# number (1).e5 # method call, since you really mean it The decimal point without a fractional part looks bizarre to me: 1.e5 # syntax error Surely +. and -. are invalid syntax? (\.\d+)? , not (\.\d*)? . -- Gordon Henriksen [EMAIL PROTECTED]
Re: my $pi is constant = 3;
Larry Wall wrote: On Wed, Aug 17, 2005 at 01:56:35PM +1000, Adam Kennedy wrote: : : : If not a special form, should this work? : : : : my $pi is constant; : : $pi = 3; : : That could be made to work by defining constant to mean you can assign : to it if it's undefined. But then it gets a little harder to reason : about it if $pi can later become undefined. I suppose we could : disallow undefine($pi) though. : : Which would basically throw away compile-time optimizations relating to : constants wouldn't it? You could still reason about it if you can determine what the initial value is going to be. But certainly that's not a guarantee, which is one of the reasons we're now calling this write/bind-once behavior readonly and moving true constants to a separate declarator: my $pi is readonly; $pi = 3; vs constant $pi = 3; or constant Num pi = 3; or if you like, even constant π = 3; Larry OK, so then there is not is constant at all... just is readonly? Makes a lot more sense to me. Adam
Re: Time::Local
On Aug 17, 2005, at 00:29 , Larry Wall wrote: which gives us these possibilities. 大務big / (perform) duty Perl6 to people here. 太夢fat, big / dream Perl6 for the rest of us. 対夢oppose, against, pair / dream Pugs? 待夢wait / dream Perl6 to Oreilly ? 滞夢stop, stagnate / dream Perl6 to kansai.pm :) All sounds pretty perl6 to me. Oh, be careful of this one. 台無stand, platform / not, none, cease to be Usually this one reads 'Dai-Nashi' (kun-yomi), meaning to blow from grounds up. Dan the Man from a Place with Too Many Puns and Funs
Re: Serializing code
Hi,
Yuval Kogman nothingmuch at woobling.org writes:
So now that the skeptics can see why this is important, on the
design side I'd like to ask for ideas on how the code serialization
looks...
sub { $?DOM.document.write(phello world!/p) }.emit(
:runtime($browser_autodetect_object),
# this can be guessed by asking the $runtime object:
# :languagejavascript,
);
This is superficially nice,
Indeed!
but here's what's missing:
[...]
- what exactly is a code object?
- a wrapper for some PIL code
- that can be executed by the runtime
Code objects may as well be executed at compile-time
(think macros, use and BEGIN blocks), but...:
sub foo { $?DOM.document.write(...) }
BEGIN { foo() }; # error, there's no $?DOM object
# at compile-time!
- what exactly is code.emit
- also an object?
Well, you call code.emit above, so it's probably a Code
object, even though it calls subs and methods from the
Perl6::Internals namespace (or somesuch).
- handling of data
- types of:
- globals?
I've probably misunderstood you, but can't globals, like all
other variables, have any type you want them to have?
- closures?
A subclass of Code, e.g. Bare.
- two examples of data sharing policies:
- the border between the webapp and the browser is
smudged by serialization and proxy objects
- the border between the webapp and the browser is
clear
and distinct, and calls between the two are done by
explicitly invoking one runtime from the other
I'd like to have a pragma to switch between these policies.
--Ingo
Re: Hoping that Params::Validate is not needed in Perl6
On Thu, Aug 18, 2005 at 11:03:22AM -0500, Dave Rolsky wrote: : Hurry up and finish. I want to use this language, darnit! And yes, I : know about pugs, obviously, but for production usage I need less of a : moving target ;) Yes, Perl 6 is a moving target--but one of the most bothersome facts of life is that, to get anywhere you're not, you have to move... Larry
Re: Hoping that Params::Validate is not needed in Perl6
On Wed, 2005-08-17 at 23:43 -0500, Dave Rolsky wrote: But I'd really like to get this stuff done at compile time wherever possible. If I write this: validate( credit_card_number: $number ); it should blow up at compile time, right? Does that depend on how closed you want Perl 6 to think your world is at compile time? -- c
Re: Hoping that Params::Validate is not needed in Perl6
On Thu, Aug 18, 2005 at 10:02:23AM -0700, chromatic wrote: On Wed, 2005-08-17 at 23:43 -0500, Dave Rolsky wrote: But I'd really like to get this stuff done at compile time wherever possible. If I write this: validate( credit_card_number: $number ); BTW, the colon is on the left: :credit_card_number($number) it should blow up at compile time, right? Does that depend on how closed you want Perl 6 to think your world is at compile time? Right, because introducing new multi variant at runtime is a desired feature. Which is why I think closed should not be limited to classes, but should extend to packages as well... Thanks, /Autrijus/ pgpx5jRaNhflL.pgp Description: PGP signature
Re: my $pi is constant = 3;
On Wed, Aug 17, 2005 at 05:31:12PM +, [EMAIL PROTECTED] wrote:
: Not only that, but what if what I want is a named constnat undef value?
If we went with bind once rather than write once semantics then after
my $foo is readonly := undef;
$foo could not be rebound, but saying
my $foo is readonly;
$foo := bar();
could still be made to work. But that means that $foo *as a container*
would have to remember if its value exists rather than relying on
the value itself knowing if it's defined. (But that's essentially
the same distinction we make for defaults in signatures: if you pass
undef as an argument, it doesn't trigger default setting.)
In other words, you could desugar
sub foo ($a = 1) {...}
to
sub foo ($a) {
$a = 1 unless exists $a;
...
}
Larry
Re: my $pi is constant = 3;
On Thu, Aug 18, 2005 at 10:09:16AM -0700, Larry Wall wrote:
In other words, you could desugar
sub foo ($a = 1) {...}
to
sub foo ($a) {
$a = 1 unless exists $a;
...
}
I like this. Can we go for it, at least for this week? :)
Thanks,
/Autrijus/
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Re: my $pi is constant = 3;
On Fri, Aug 19, 2005 at 01:15:23AM +0800, Autrijus Tang wrote:
On Thu, Aug 18, 2005 at 10:09:16AM -0700, Larry Wall wrote:
In other words, you could desugar
sub foo ($a = 1) {...}
to
sub foo ($a) {
$a = 1 unless exists $a;
...
}
I like this. Can we go for it, at least for this week? :)
Also, preemptively -- I think the corresponding delete $a is insane,
as it would just lift up the constancy problem one level, defeating the
no rebinding restriction.
Thanks,
/Autrijus/
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Re: Serializing code
On Thu, Aug 18, 2005 at 12:24:40 +, Ingo Blechschmidt wrote:
Hi,
Yuval Kogman nothingmuch at woobling.org writes:
So now that the skeptics can see why this is important, on the
design side I'd like to ask for ideas on how the code serialization
looks...
sub { $?DOM.document.write(phello world!/p) }.emit(
:runtime($browser_autodetect_object),
# this can be guessed by asking the $runtime object:
# :languagejavascript,
);
This is superficially nice,
Indeed!
but here's what's missing:
[...]
- what exactly is a code object?
- a wrapper for some PIL code
- that can be executed by the runtime
Code objects may as well be executed at compile-time
(think macros, use and BEGIN blocks), but...:
But it's still the runtime that runs them ;-)
Compilation has a runtime that runs the compiler, and compile-time
code. The output may be handed down to another runtime that actually
runs.
sub foo { $?DOM.document.write(...) }
BEGIN { foo() }; # error, there's no $?DOM object
# at compile-time!
Unless you're compiling in the browser ;-)
Well, you call code.emit above, so it's probably a Code
object, even though it calls subs and methods from the
Perl6::Internals namespace (or somesuch).
Not code, but the return value of code.emit
- handling of data
- types of:
- globals?
I've probably misunderstood you, but can't globals, like all
other variables, have any type you want them to have?
Not types in the kind of value type... Read it as:
handling of data... what types of data... global variables are
types of data
- closures?
A subclass of Code, e.g. Bare.
How are they stored?
I'd like to have a pragma to switch between these policies.
I doubt a pragma is enough - we need full introspection and fine
grained control for this, both in the lexical and the dynamic
scopes.
--
() Yuval Kogman [EMAIL PROTECTED] 0xEBD27418 perl hacker
/\ kung foo master: /me supports the ASCII Ribbon Campaign: neeyah!!!
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Re: Serializing code
On Thu, Aug 18, 2005 at 08:22:20PM +0300, Yuval Kogman wrote:
sub foo { $?DOM.document.write(...) }
BEGIN { foo() }; # error, there's no $?DOM object
# at compile-time!
Unless you're compiling in the browser ;-)
Which... is possible, and that's how I plan to support eval().
Thanks,
/Autrijus/
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Re: my $pi is constant = 3;
On Fri, Aug 19, 2005 at 01:15:23AM +0800, Autrijus Tang wrote:
: On Thu, Aug 18, 2005 at 10:09:16AM -0700, Larry Wall wrote:
: In other words, you could desugar
:
: sub foo ($a = 1) {...}
:
: to
:
: sub foo ($a) {
: $a = 1 unless exists $a;
: ...
: }
:
: I like this. Can we go for it, at least for this week? :)
Sure. Though it probably also wants to stay as metadata associated
with the signature, since part of the reason for putting it in
the signature in the first place is so that optimizers can install
constants on the caller end, at least for ordinary sub calls. Also,
desugaring a predeclaration would tend to cloak the yadae at the end,
but maybe that's not a problem unless you use the presence of bare
yadae in the body to suppress redefinition warnings.
Larry
Re: my $pi is constant = 3;
On Fri, Aug 19, 2005 at 01:17:51AM +0800, Autrijus Tang wrote: : Also, preemptively -- I think the corresponding delete $a is insane, : as it would just lift up the constancy problem one level, defeating the : no rebinding restriction. I think in general the only time you're allowed to monkey with the symbol table is when you're compiling, so deletions could just fall into that category. The compiler has to be able to depend on its symbols not going away once it's done. Larry
Re: my $pi is constant = 3;
On Thu, Aug 18, 2005 at 10:26:00AM -0700, Larry Wall wrote:
Sure. Though it probably also wants to stay as metadata associated
with the signature, since part of the reason for putting it in
the signature in the first place is so that optimizers can install
constants on the caller end, at least for ordinary sub calls. Also,
desugaring a predeclaration would tend to cloak the yadae at the end,
but maybe that's not a problem unless you use the presence of bare
yadae in the body to suppress redefinition warnings.
The full desugared form is, I think:
our foo; # lifted to beginning of package!
...
BEGIN {
foo := a Sub is stub {
($a) := ?Internals::GETARGS();
$a = 1 unless exists $a;
# real body begins here
...
};
}
with the is stub -- not neccessarily exposed to the user level --
filled in by a parser rule, i.e. a predefined macro.
Does this sound sane?
Thanks,
/Autrijus/
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Re: my $pi is constant = 3;
On Fri, Aug 19, 2005 at 01:36:30AM +0800, Autrijus Tang wrote:
: On Thu, Aug 18, 2005 at 10:26:00AM -0700, Larry Wall wrote:
: Sure. Though it probably also wants to stay as metadata associated
: with the signature, since part of the reason for putting it in
: the signature in the first place is so that optimizers can install
: constants on the caller end, at least for ordinary sub calls. Also,
: desugaring a predeclaration would tend to cloak the yadae at the end,
: but maybe that's not a problem unless you use the presence of bare
: yadae in the body to suppress redefinition warnings.
:
: The full desugared form is, I think:
:
: our foo; # lifted to beginning of package!
: ...
: BEGIN {
: foo := a Sub is stub {
: ($a) := ?Internals::GETARGS();
: $a = 1 unless exists $a;
: # real body begins here
: ...
: };
: }
:
: with the is stub -- not neccessarily exposed to the user level --
: filled in by a parser rule, i.e. a predefined macro.
:
: Does this sound sane?
No, but it sounds least insane. :-)
Larry
Re: my $pi is constant = 3;
On Fri, Aug 19, 2005 at 01:36:30AM +0800, Autrijus Tang wrote:
BEGIN {
foo := a Sub is stub {
($a) := ?Internals::GETARGS();
$a = 1 unless exists $a;
# real body begins here
...
};
}
Er, sorry, the ($a) would need a my() scope identifier, as with all
parameters and hoisted mid-block my() declarations.
Also, a Sub should read a sub.
Thanks,
/Autrijus/
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