On Tue, May 26, 2009 at 04:10:45PM -0700, yary wrote:
> On Tue, May 26, 2009 at 1:57 PM, Patrick R. Michaud <pmich...@pobox.com>
> wrote:
> > On Mon, May 25, 2009 at 12:37:34PM -0700, yary wrote:
> > How about...?
> >
> > sub odd { ^$a % 2 }
> typo. "sub odd {$^a % 2}" works (caret goes between "$" and "a")
Correct, that's a typo.
> > say grep &odd, 0..6;
> nice. I need to learn the differences between calling a sub as "odd"
> vs "&odd" in p6. Haven't gotten that far in the synopses yet.
In p6, one always uses the sigil to refer to the sub itself; the bare
identifier form invokes it.
> I was wondering why the perl5 example didn't work in p6- $_ is a
> contextual variable, so why doesn't the body of "odd" get its $_ value
> from grep in something like this:
> sub odd_a { $_ % 2}
This is really equivalent to
sub odd_a(*...@_, *%_) { $_ % 2 }
Every Routine gets its own $_ that isn't inherited from the outer
lexical context (and is initialized to undef).
Beyond that, what is really happening with
say grep &odd_a, 0..6
is that grep is performing a smart-match of each value of 0..6
with &odd_a, and smart-matching a value to a Code object invokes
the Code object with the value as an argument.
Pm
