Euler #4

draegtun had a nice post on Project Euler #4. The goal is to find the largest palindromic product of two three digit numbers, and he lists solutions in Clojure and Python and a bunch in Perl 5. There is also a Perl 6 version by trenton in euler_bench on github.

I thought I'd try my hand at a more idiomatic Perl 6 version. Here's my first attempt:

((100..999) X (100..999)).map({$^a * $^b}).grep({$_ eq $_.flip}).max.say

Unfortunately, the usual caveats apply. This blows up the current Rakudo, no doubt because without lazy lists it tries to construct a huge list entirely in memory and then collapses. Rakudo ng has lazy lists, but it doesn't have grep or max yet. So for now, this is purely a hypothetical implementation.

However, with any luck, Rakudo ng will handle this by the end of the week...