Add link to STD.pm where official documentation listed
On #perl6 Larry said that STD is a part of the specification for perl6. Would it be possible to include a link to STD.pm in the list of official documentation? There are things in STD that are not in the specifications, eg., default values for optional parameters should come after traits assigned to the parameters.
Re: Array variables as formal parameters ???
On May 23, 2009 11:31:35 pm John M. Dlugosz wrote:
Henry Baragar Henry.Baragar-at-instantiated.ca |Perl 6| wrote:
sub f2 (@y) {say @y.WHAT; say +...@y}; f2(Nil);
Array()
1
Why doesn't +...@y produce 0, not 1? It's an empty list.
From rakudo:
sub f2 (@y) {say @y[0]}; f2(Nil);
Nil()
Henry
Uh, @y is an Array of one item, that one item being Nil.
I think the intent was to be an empty list. Nil is not supposed to go
into lists, but to become nothing when used in such a way. Wrapping Nil
into a list when it wasn't a list at all to begin with is totally
missing the point. And where did the wrapping Array come from?
Good question, since Nil does Positional, as evidenced by rakudo:
say Nil ~~ Positional
1
Should report this as a bug?
Henry
At its
simplest, Nil is an object whose Positional personality shows an empty
list, and that's what the @ variable uses.
--John
--
Henry Baragar
Instantiated Software
416-907-8454 x42
r26928 - docs/Perl6/Spec
Author: schwarzer
Date: 2009-05-24 21:46:24 +0200 (Sun, 24 May 2009)
New Revision: 26928
Modified:
docs/Perl6/Spec/S02-bits.pod
docs/Perl6/Spec/S06-routines.pod
docs/Perl6/Spec/S19-commandline.pod
docs/Perl6/Spec/S28-special-names.pod
Log:
[Perl6/Spec] typos
Modified: docs/Perl6/Spec/S02-bits.pod
===
--- docs/Perl6/Spec/S02-bits.pod2009-05-24 05:05:44 UTC (rev 26927)
+++ docs/Perl6/Spec/S02-bits.pod2009-05-24 19:46:24 UTC (rev 26928)
@@ -2332,7 +2332,7 @@
}
This tends to be more efficient since it only has to do one mixin
-at the the end of the block. Note that the slang declaration has
+at the end of the block. Note that the slang declaration has
nothing to do with package CRegex, but only with C$~Regex.
Sublanguages are in their own namespace (inside the current value
of C%?LANG, in fact). Hence Caugment is modifying one of the local
Modified: docs/Perl6/Spec/S06-routines.pod
===
--- docs/Perl6/Spec/S06-routines.pod2009-05-24 05:05:44 UTC (rev 26927)
+++ docs/Perl6/Spec/S06-routines.pod2009-05-24 19:46:24 UTC (rev 26928)
@@ -145,7 +145,7 @@
sub swap (*...@_ is rw, *%_ is rw) { @_[0,1] = @_[1,0]; %_status =
Q:S; }
Note: the Crw container trait is automatically distributed to the
-individual elements by the the slurpy star even though there's no
+individual elements by the slurpy star even though there is no
actual array or hash passed in. More precisely, the slurpy star
means the declared formal parameter is Inot considered readonly; only
its elements are. See L/Parameters and arguments below.
Modified: docs/Perl6/Spec/S19-commandline.pod
===
--- docs/Perl6/Spec/S19-commandline.pod 2009-05-24 05:05:44 UTC (rev 26927)
+++ docs/Perl6/Spec/S19-commandline.pod 2009-05-24 19:46:24 UTC (rev 26928)
@@ -398,8 +398,8 @@
=item ++CMD --command-line-parser *parser* ++/CMD
Add a command-line processor. When this option is parsed, it immediately
-triggers an action that affects or replaces the the command-line parser.
-Therefore, it's a good idea to put this option as early as possible in the
+triggers an action that affects or replaces the command-line parser.
+Therefore, it is a good idea to put this option as early as possible in the
argument list.
=item --check-syntax, -c
Modified: docs/Perl6/Spec/S28-special-names.pod
===
--- docs/Perl6/Spec/S28-special-names.pod 2009-05-24 05:05:44 UTC (rev
26927)
+++ docs/Perl6/Spec/S28-special-names.pod 2009-05-24 19:46:24 UTC (rev
26928)
@@ -52,7 +52,7 @@
the outermost definition of these variables are kept in the CPROCESS
package.
-The C$=foo variables are related to the the C$?foo variables
+The C$=foo variables are related to the C$?foo variables
insofar as the text of the program is known at compile time, so the
values are static. However, the different twigil indicates that the
variable contains POD data, which is primarily under user control
Re: Array variables as formal parameters ???
Henry Baragar Henry.Baragar-at-instantiated.ca |Perl 6| wrote: Good question, since Nil does Positional, as evidenced by rakudo: say Nil ~~ Positional 1 Should report this as a bug? Henry At the very least, it is the most simple test case for Nil. Should be in the test suite.
Re: Array variables as formal parameters ???
On May 23, 2009 11:26:16 pm John M. Dlugosz wrote:
From whence did it get its Item container?
OK, my brain made a wrong turn some time on Tuesday.
Let me review the basics.
From S02:
|$x| may be bound to any object, including any object that can be bound
to any other sigil.
Perl variables have two associated types: their value type and their
implementation type.
Value type = of, implementation type is the type of the container itself.
my $spot is Scalar; # this is the default
I think (that I may be getting out of my depth here) that the implementation
type refers to the container at a deeper level. That is, Scalar is a Perl
container and not a Java nor Ruby container, which allows having objects from
different languages (with their different semantics) in a single application.
From S03:
A new form of assignment is present in Perl 6, called /binding/, used in
place of typeglob assignment. It is performed with the |:=| operator.
Instead of replacing the value in a container like normal assignment, it
replaces the container itself. For instance:
my $x = 'Just Another';
my $y := $x;
$y = 'Perl Hacker';
At first, I thought that this was a aliasing mechanism, but now I worry that
this is how we have to assign non-Perl variables in a Perl application. That
is, the semantics of assignment differ depending the container type.
From S12:
Method calls on mutable scalars always go to the object contained in the
scalar (autoboxing value types as necessary):
$result = $object.doit();
$length = mystring.codes;
Method calls on non-scalar variables just calls the |Array|, |Hash| or
|Code| object bound to the variable:
$elems = @array.elems;
@keys = %hash.keys;
$sig = sub.signature;
Use the prefix |VAR| macro on a scalar variable to get at its underlying
|Scalar| object:
if VAR($scalar).readonly {...}
||
So, if you say
my $x;
then $x is bound to a newly-created Scalar (not worrying about
conflating the name the Role and the concrete type at this point).
my $x = 'Just Another';
Now the item assignment operates on the container, storing the Str
instance within it. $x is bound to a container, and the container
contains (only) one Str instance.
Rephrasing: $x is a Perl container holding a Str object whose content
(value?) is 'Just Another'.
Basically, I was thinking that scalar variables always are bound to item
containers which contain the actual value. In fact, this was originally
drilled into me: containers vs values! That variables always directly
hold some kind of container. I suppose that's been changed at some
point, perhaps long ago, but the synopses didn't dissuade me from that
early belief.
I don't think it has been changed, I think that if you don't understand how
tie is implemented in Perl5 (which is referenced heavily in the synopsis),
then it is easy to miss the distinctions being made. (It doesn't help that
the Implementation type is in the middle of a bunch of higher level types).
Anyway, as for your (Henry) example from Rakudo:
my $x = 1, 2, 3;
According to the synopses, this should be analogous to the previous
example, where $x now is bound to an item that contains a Capture
containing 3 Ints.
Assuming Capture vs Array is simply out of date implementation, just
focus on the parameter passing. $x is bound to a Scalar. But What I
Mean is for the formal parameter @y to get bound to the item in the
container, the list of Ints.
===How does that happen?
The List prefix precedence section of Synopsis 3 says that it returns a list.
It goes on a bit about the contortions that must be done to do this.
Now back to straightening out my misconceptions about scalars _always_
holding item containers. If $x is bound to an Array, for example, the
compiled code can't be doing the indirection innately.
So it follows that the method forwarding is a property of the object
that the method is originally called on. That is, the Scalar (and any
tied item container implementations) are written to forward all
methods to the contained object. The compiler sees $x.foo() and doesn't
know anything about $x other than that it's some object, so it codes a
message dispatch to it. If $x holds a normal object, the foo method
gets called via the normal dispatching rules. But Scalar implements
something that catches all methods and forwards them to the contained item.
===Right?
Not quite (I think). As mentioned above, I think that the Scalar is the the
thing that knows how/which dispatch to use.
That would imply that if a scalar happened to contain another scalar, e.g.
my $x = Scalar.new;
($x is bound to a Scalar which contains a Scalar which contains undef)
then any method called on $x would trigger the same behavior when the
contained object gets it, and be forwarded all the way down, no
r26929 - docs/Perl6/Spec
Author: jdlugosz Date: 2009-05-25 06:10:06 +0200 (Mon, 25 May 2009) New Revision: 26929 Modified: docs/Perl6/Spec/S03-operators.pod Log: Code to Callable, clarify Type under smart matching (see http://irclog.perlgeek.de/perl6/2009-05-24#i_1171474 Modified: docs/Perl6/Spec/S03-operators.pod === --- docs/Perl6/Spec/S03-operators.pod 2009-05-24 19:46:24 UTC (rev 26928) +++ docs/Perl6/Spec/S03-operators.pod 2009-05-25 04:10:06 UTC (rev 26929) @@ -12,8 +12,8 @@ Maintainer: Larry Wall la...@wall.org Date: 8 Mar 2004 - Last Modified: 17 May 2009 - Version: 165 + Last Modified: 24 May 2009 + Version: 166 =head1 Overview @@ -3060,8 +3060,8 @@ $_X Type of Match Implied Match if (given $_) === = === -Any Code:($) item sub truth X($_) -Any Code:() simple closure truthX() (ignoring $_) +Any Callable:($) item sub truth X($_) +Any Callable:() simple closure truthX() (ignoring $_) Any undef undefined not .defined Any * block signature match block successfully binds to |$_ Any .foo method truth?X i.e. ?.foo @@ -3105,7 +3105,7 @@ Any Type type membership $_.does(X) Signature Signature sig compatibility $_ is a subset of X ??? -Code Signature sig compatibility $_.signature is a subset of X ??? +Callable Signature sig compatibility $_.sig is a subset of X ??? Capture Signature parameters bindable $_ could bind to X (doesn't!) Any Signature parameters bindable |$_ could bind to X (doesn't!) @@ -3150,7 +3150,9 @@ === === List SeqArray KeySet KeyBag KeyHash Hash -Class Enum Role Type +named values created with + Class, Enum, or Role, + or generic type binding Type Subst Regex Char CatStr Int UInt etc. Num @@ -3208,7 +3210,7 @@ $_ XType of Match Wanted What to use on the right == === -CodeAny item sub truth .ACCEPTS(X) or .(X) +Callable Any item sub truth .ACCEPTS(X) or .(X) Range Any in range .ACCEPTS(X) TypeAny type membership.ACCEPTS(X) or .does(X) Regex Any pattern match .ACCEPTS(X)
Re: Array variables as formal parameters ???
Henry Baragar Henry.Baragar-at-instantiated.ca |Perl 6| wrote:
On May 23, 2009 11:26:16 pm John M. Dlugosz wrote:
From whence did it get its Item container?
OK, my brain made a wrong turn some time on Tuesday.
Let me review the basics.
From S02:
|$x| may be bound to any object, including any object that can be bound
to any other sigil.
Perl variables have two associated types: their value type and their
implementation type.
Value type = of, implementation type is the type of the container itself.
my $spot is Scalar; # this is the default
I think (that I may be getting out of my depth here) that the implementation
type refers to the container at a deeper level. That is, Scalar is a Perl
container and not a Java nor Ruby container, which allows having objects from
different languages (with their different semantics) in a single application.
That's right. The way I learned it (and I worry about these
early-learned principles being out of date!) is that using something
other than the default Scalar class is like tieing in Perl 5. You
create your own item container that (presumably, following Perl 5's
names) implements STORE and FETCH. That could be a foreign variable I
suppose.
If you wrote a class MyScalar, it could, for example, access the Windows
registry when accessed, or automatically read or update a value from a
GUI form.
From S03:
A new form of assignment is present in Perl 6, called /binding/, used in
place of typeglob assignment. It is performed with the |:=| operator.
Instead of replacing the value in a container like normal assignment, it
replaces the container itself. For instance:
my $x = 'Just Another';
my $y := $x;
$y = 'Perl Hacker';
At first, I thought that this was a aliasing mechanism, but now I worry that
this is how we have to assign non-Perl variables in a Perl application. That
is, the semantics of assignment differ depending the container type.
I'm assuming that the container defines what item assignment means. At
the very least, it will have the STORE method. But I want to have
infix:= definable in general without having to make it masquerade as
an Item Container.
From S12:
Method calls on mutable scalars always go to the object contained in the
scalar (autoboxing value types as necessary):
$result = $object.doit();
$length = mystring.codes;
Method calls on non-scalar variables just calls the |Array|, |Hash| or
|Code| object bound to the variable:
$elems = @array.elems;
@keys = %hash.keys;
$sig = sub.signature;
Use the prefix |VAR| macro on a scalar variable to get at its underlying
|Scalar| object:
if VAR($scalar).readonly {...}
||
So, if you say
my $x;
then $x is bound to a newly-created Scalar (not worrying about
conflating the name the Role and the concrete type at this point).
my $x = 'Just Another';
Now the item assignment operates on the container, storing the Str
instance within it. $x is bound to a container, and the container
contains (only) one Str instance.
Rephrasing: $x is a Perl container holding a Str object whose content
(value?) is 'Just Another'.
Agree. Scalar is a type of item container.
Basically, I was thinking that scalar variables always are bound to item
containers which contain the actual value. In fact, this was originally
drilled into me: containers vs values! That variables always directly
hold some kind of container. I suppose that's been changed at some
point, perhaps long ago, but the synopses didn't dissuade me from that
early belief.
I don't think it has been changed, I think that if you don't understand how
tie is implemented in Perl5 (which is referenced heavily in the synopsis),
then it is easy to miss the distinctions being made. (It doesn't help that
the Implementation type is in the middle of a bunch of higher level types).
Taken literally, it has: $x may be bound to any object, including any
object that can be bound to any other sigil.
That means that $x may be bound to an item container containing some
other object, or may be bound directly to some other kind of object.
That's my fundamental understanding at this point. Unless something
*really*strange* has become of item container ... (Larry, please?)
Anyway, as for your (Henry) example from Rakudo:
my $x = 1, 2, 3;
According to the synopses, this should be analogous to the previous
example, where $x now is bound to an item that contains a Capture
containing 3 Ints.
Assuming Capture vs Array is simply out of date implementation, just
focus on the parameter passing. $x is bound to a Scalar. But What I
Mean is for the formal parameter @y to get bound to the item in the
container, the list of Ints.
===How does that happen?
The List prefix precedence section of Synopsis 3 says that it returns a list.
It goes on a bit about the contortions that must be
