Re: Challenge: Another Infinite Lazy List


good chemistry is complicated, and a little bit messy -LW
	PerlMonks

Re: Challenge: Another Infinite Lazy List

by Limbic~Region (Chancellor)

on Mar 22, 2005 at 00:19 UTC ( [id://441347]=note: print w/replies, xml )

Need Help??

in reply to Challenge: Another Infinite Lazy List

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;
    };
}
[download]

Cheers - L~R