为什么我收到此错误消息？
#!perl6
use v6;
my @a = 1..3;
my @b = 7..10;
my @c = 'a'..'d';
for zip(@a;@b;@c) -> $nth_a,$nth_b,$nth_c { ... };
# Output:
# ===SORRY!===
# Unable to parse postcircumfix:sym<( )>,couldn't find final ')' at line 9
解决方法
Rakudo尚未实现lol(“列表列表”)表单,因此无法解析@a; @b; @c.出于同样的原因,zip还没有一个包含三个列表的表单.显然,错误消息不是很棒.
目前还没有一个好的解决方法,但是这里有一些可以完成工作的东西：
sub zip3(@a,@b,@c) {
my $a-list = flat(@a.list);
my $b-list = flat(@b.list);
my $c-list = flat(@c.list);
my ($a,$b,$c);
gather while ?$a-list && ?$b-list && ?$c-list {
$a = $a-list.shift unless $a-list[0] ~~ ::Whatever;
$b = $b-list.shift unless $b-list[0] ~~ ::Whatever;
$c = $c-list.shift unless $c-list[0] ~~ ::Whatever;
take ($a,$c);
}
}
for zip3(@a,@c) -> $nth_a,$nth_c {
say $nth_a ~ $nth_b ~ $nth_c;
}