Jonathan Scott Duff wrote:
Because what you do with a hypothetical has to be reversible.
I thought it was just the hypothetical's existence that has to be
reversible.
That's not my understanding. You need to be able to cope with this too:
rule alias :w { \$ $name:=ident [is named
Damian Conway wrote:
Though leaving optimization in the hands of the programmer
is generally a Bad Idea.
That doesn't sound like a Perl slogan.
It's also a matter of syntactic consistency. It has to be := for
inlined bindings (i.e. rx/ $name:=ident /) because otherwise
we make = meta
At 6:59 AM + 9/7/02, Damian Conway wrote:
Jonathan Scott Duff wrote:
Sounds like an optimization that should be in the hands of the
programmer to me.
Possibly. Though leaving optimization in the hands of the programmer
is generally a Bad Idea.
Oh, I dunno... If that programmer is me or one
Jonathan Scott Duff wrote:
This continues to make no sense to me. The hypotheticality of a
variable seems quite orthogonal to what you do with it (bind, assign,
whatever). Why should these two things be intimate?
Because what you do with a hypothetical has to be reversible.
And binding is
Damian Conway wrote:
Because what you do with a hypothetical has to be reversible.
And binding is far more cheaply reversible than assignment.
Why not leave it in the language spec then? If it's too
hard to implement, then the first release of Perl 6 can
leave it out. Someday somebody might
On Thu, Sep 05, 2002 at 03:38:03PM +, Damian Conway wrote:
Jonathan Scott Duff wrote:
This continues to make no sense to me. The hypotheticality of a
variable seems quite orthogonal to what you do with it (bind, assign,
whatever). Why should these two things be intimate?
Because
Ken Fox wrote:
/ $x := (gr\w+) /vs/ (gr\w+) { let $x = $1 } /
Shouldn't they both use C := ?
They should. The second version is a typo. It should be:
/ (gr\w+) { let $x := $1 } /
Depends on what you want. The $x := in the rule binds the
On Wed, Sep 04, 2002 at 11:27:46AM +, Damian Conway wrote:
This is not what Larry has said previously. He said that only
binding can be used with Clet variables and that only Clet
variable assignments are undone on backtracking.
It seems odd to require two syntactic elements to achieve
On Wed, 2002-09-04 at 14:38, Jonathan Scott Duff wrote:
my $x;
/ (\S*) { let $x = .pos } \s* foo /
After this pattern, $x will be set to the ending position of
$1--but only if the pattern succeeds. If it fails, $x is
restored to undef
On Wed, 2002-09-04 at 07:28, Damian Conway wrote:
Aaron Sherman wrote:
Hmm... I had not thought of the copy aspect. Certainly, the code version
is more flexible. You could define C$x above as anything. For example:
/ (gr\w+) {let $x = Gr_Thing.new($1)} /
The binding
Jonathan Scott Duff wrote:
It seems odd to require two syntactic elements to achieve one semantic.
And actually, after looking at A5, that's not what Larry wrote:
my $x;
/ (\S*) { let $x = .pos } \s* foo /
A typo, I believe. He has been very consistent in
On Wed, Sep 04, 2002 at 10:25:39PM +, Damian Conway wrote:
Jonathan Scott Duff wrote:
It seems odd to require two syntactic elements to achieve one semantic.
And actually, after looking at A5, that's not what Larry wrote:
my $x;
/ (\S*) { let $x = .pos }
On Mon, 2 Sep 2002 23:50:18 -0400 (EDT), Trey Harris wrote:
In a message dated 2 Sep 2002, Aaron Sherman writes:
{
my $x = 2;
my $y = The grass is green;
$y =~ /(gr\w+) {let $x = $1}/;
}
Yes. $0{x} would be set to grass. A lexical
Peter Haworth wrote:
Also the different operators used (:= inside the rule, = inside the code)
seems a bit confusing to me; I can't see that they're really doing anything
different:
/ $x := (gr\w+) /vs/ (gr\w+) { let $x = $1 } /
Shouldn't they both use C := ?
Depends on
On Tue, 2002-09-03 at 11:35, Ken Fox wrote:
Peter Haworth wrote:
Also the different operators used (:= inside the rule, = inside the code)
seems a bit confusing to me; I can't see that they're really doing anything
different:
/ $x := (gr\w+) /vs/ (gr\w+) { let $x = $1 } /
I'm working on a library of rules and subroutines for dealing with UNIX
system files. This is really just a mental exercise to help me grasp the
new pattern stuff from A5.
I've hit a snag, though, on hypothetical variables. How would this code
work?
{
my $x = 2;
my $y =
In a message dated 2 Sep 2002, Aaron Sherman writes:
I'm working on a library of rules and subroutines for dealing with UNIX
system files. This is really just a mental exercise to help me grasp the
new pattern stuff from A5.
I've hit a snag, though, on hypothetical variables. How would this
On Mon, 2002-09-02 at 23:50, Trey Harris wrote:
No. $0{x} would be set to grass. $x would stay as 2. $x is in a
different scope from the hypothetical, so it doesn't get touched.
Ok, it's just taking some time for me to get my head around just what
C/.../ and Crule{...} are, but I'm getting
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