Question

我正在使用以下代码尝试供稿运算符：

my $limit=10000000;
my $list=(0,1...4);
sub task($_,$name) {
    say "Start $name on $*THREAD";
    loop ( my $i=0; $i < $limit; $i++ ){};
    say "End $name";
    Nil;
}

sub stage( &code, *@elements --> Seq) {
    map(&code,  @elements);
}

sub feeds() {
    my @results;
    $list
    ==> map ({ task($_, "stage 1"); say( now - ENTER now );$_+1})
    ==> map ({ task($_, "stage 2"); say( now - ENTER now );$_+1})
    ==> stage ({ task($_, "stage 3"); say( now - ENTER now );$_+1}) 
    ==> @results;

    say @results;
}

feeds();

任务子只是一个循环，用于刻录cpu周期并显示所使用的线程
stage子是地图子的包装器

运行时的输出为：

Start stage 1 on Thread<1>(Initial thread)
End stage 1
0.7286811
Start stage 2 on Thread<1>(Initial thread)
End stage 2
0.59053989
Start stage 1 on Thread<1>(Initial thread)
End stage 1
0.5955893
Start stage 2 on Thread<1>(Initial thread)
End stage 2
0.59050998
Start stage 1 on Thread<1>(Initial thread)
End stage 1
0.59472201
Start stage 2 on Thread<1>(Initial thread)
End stage 2
0.5968531
Start stage 1 on Thread<1>(Initial thread)
End stage 1
0.5917188
Start stage 2 on Thread<1>(Initial thread)
End stage 2
0.587358
Start stage 1 on Thread<1>(Initial thread)
End stage 1
0.58689858
Start stage 2 on Thread<1>(Initial thread)
End stage 2
0.59177099
Start stage 3 on Thread<1>(Initial thread)
End stage 3
3.8549498
Start stage 3 on Thread<1>(Initial thread)
End stage 3
3.8560015
Start stage 3 on Thread<1>(Initial thread)
End stage 3
3.77634317
Start stage 3 on Thread<1>(Initial thread)
End stage 3
3.6754558
Start stage 3 on Thread<1>(Initial thread)
End stage 3
3.672909
[3 4 5 6 7]

@result中的结果正确（来自$list的输入以3递增3）

前两个阶段的输出拉/交替，但是直到完成第2阶段的所有输入后，第三阶段才会执行

我的map子包装器出现问题了吗？

与直接调用map相比，在包装器中评估所需的时间也明显更长。

感谢您的帮助。

Answer 1

slurpy参数正在等待消耗传递给它的整个序列。考虑以下两者之间的区别：

perl6 -e 'sub foo($) { }; my $items := gather for 1..Inf { say $_ }; foo($items);'

perl6 -e 'sub foo(*@) { }; my $items := gather for 1..Inf { say $_ }; foo($items);'

第一个示例将结束，第二个示例将永远结束。因此，您需要将舞台功能更改为：

sub stage( &code, $elements --> Seq) {
    map(&code,  $elements);
}

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