Here's a slightly more direct implementation of that:

use strict;
$|++;

my $generator = do {
  my $num = 1;
  sub { ++$num }
};

while (1) {
  my $prime = $generator->();
  print "$prime\n";
  ## don't let any multiple of these escape:
  my $oldgenerator = $generator;
  $generator = sub {
    {
      my $next_prime = $oldgenerator->();
      redo if $next_prime % $prime == 0;
      return $next_prime;
    }
  };
}
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-- Randal L. Schwartz, Perl hacker
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