Conway: Infinite work is less work

Post Syndicated from corbet original

Damian Conway writes
about the power of infinite sequences
in Perl 6.

The sequence of primes is just the sequence of positive integers,
filtered (with a .grep) to keep only the ones that are prime.
And, of course, Perl 6 already has a prime number tester: the built-in
&is-prime function. The sequence of primes never changes, so we can
declare it as a constant:

    constant p = [  (1..∞).grep( &is-prime )  ];

Now we need to extract just the strong and weak primes.