Re^3: Perl6 lazy list of code blocks

I found a bug. Using...

my @foo = { state $n=-1; $n++; sub ($x,$y) { $x+$y+$n } } ... *;
[download]

...in my sequential access code example from my previous post, the state variable $n seemed to maintain the ordinal position of each closure in the series, but it hid the bug of $n being instead a high-water mark for positional access, and so...

my $foo_0 = @foo[0].(3,5);
my $foo_1 = @foo[1].(3,5);
my $foo_2 = @foo[2].(3,5);
[download]

...produces...

10
10
10
[download]

...when what I desired was...

8
9
10
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Thus, after an additional scope trick to lexically package (in $p) the persistent state value (in $n), this is my better solution...

my @foo = { state $n=-1; $n++; my $p=$n; sub ($x,$y) { $x+$y+$p } } ..
+. *;
[download]

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Re^4: Perl6 lazy list of code blocks by moritz (Cardinal) on May 24, 2012 at 08:21 UTC
I don't know if it's a bug, it might be ordinary closure cloning at work. This works too: `my $s = { state $n=-1; $n++; sub ($x,$y) { $x+$y+$n } }; my @foo = $s ... *; say @foo[0].(3,5); say @foo[1].(3,5); say @foo[2].(3,5);` [download] Perl 6 - the future is here, just unevenly distributed	[reply] [d/l]
Re^5: Perl6 lazy list of code blocks by aes (Initiate) on May 24, 2012 at 10:34 UTC
Ah, but you're repeating the sequential access behavior that hides the bug. Try instead reversing the access order and you'll see the "high water mark" bug. `say @foo[2].(3,5); say @foo[1].(3,5); say @foo[0].(3,5);` [download] ...produces... `10 10 10` [download]	[reply] [d/l] [select]