This is Rakudo version 2016.07.1 built on MoarVM version 2016.07
implementing Perl 6.c.
现在的 Perl 6 还是比较慢的。现在我们打印从 1 开始计数的第 10000 个素数:
并发版本
sub find-prime($count) {
my $channel = Channel.new;
my $promise = start {
for ^$count {
$channel.send($_) if .is-prime;
}
LEAVE $channel.close unless $channel.closed;
}
return $channel.list but role :: { method channel { $channel } };;
}
my @primes = find-prime(110000);
for @primes {
@primes.channel.close if $++ > 5000; # hard-close the channel after 5000 found files
.say if $++ %% 100 # print every 100th file
}
say @primes[10000];
say now - INIT now;
上面的并发查找素数, 用时 35 秒多! but 的作用类似于 does。
gather/take 版
my @vals = lazy gather {
for ^Inf {
take $_ if .is-prime;
}
}
say @vals[10000];
say now - INIT now;
gather/take 类似于 Python 中的 yield , 用时 25 秒多。
普通版本
如果不使用 is-prime 函数, 查找第 10000 个素数就比较慢:
# 下面这几种写法, 性能很差
lazy gather {
CANDIDATE: for 2 .. 110000 -> $candidate {
for 2 .. sqrt $candidate -> $divisor {
next CANDIDATE if $candidate % $divisor == 0;
}
take $candidate;
}
} ==> my @vals;
say @vals[10000];
say now - INIT now;
lazy gather {
for ^Inf {
take $_ if .is-prime;
}
} ==> my @vals;
say @vals[10000];
say now - INIT now;
my @vals = lazy gather {
for 1..110000 {
take $_ if (2 ** ($_ - 1) % $_ == 1 || $_ == 2);
}
}
say @vals[10000];
say now - INIT now;
