Re: Challenge: Another Infinite Lazy List

[Limbic~Region]

My solution in the root thread required was only minimally better than my original solution (to the wrong problem). This minimally tested version is vast improvement over both previous solutions.

#!/usr/bin/perl
use strict;
use warnings;

my $end = shift || 22;
my $next = lazy_merge( [ @ARGV ? @ARGV : (2, 3, 5) ] );
print $next->(), "\n" for 1 .. $end;

sub lazy_merge {
    my ($list, $last) = (shift(), 0);

    my $by_n = sub { my ($n, $k) = (shift(), 0); return sub { $_[0] ? 
+$k += $n : $k } };
    $_ = $by_n->( $_ ) for @$list;

    return sub {
        my $low;
        for ( @$list ) {
            my $val = $_->();
            $val = $_->( 'next' ) if $val <= $last;
            $low = $val if ! defined $low || $val < $low;
        }
        return $last = $low;
    };
}