Re: Hamming Sequences and Lazy Lists (non-'functional' iterator)

[tye]

This goes through the same steps as the functional version but doesn't use much functional programming (and so is probably more efficient):

#!/usr/bin/perl -w
use strict;

sub gen {
    my %list;
    @list{@_}= map [1], 0..$#_;
    return sub {
        my @next;
        for my $m (  keys %list  ) {
            if(  ! @next  ||  $list{$m}[0] < $list{$next[0]}[0]   ) {
                @next= $m;
            } elsif(  $list{$m}[0] == $list{$next[0]}[0]  ) {
                push @next, $m;
            }
        }
        my $ret= $list{$next[0]}[0];
        for my $m (  @next  ) {
            shift @{$list{$m}};
        }
        for my $m (  keys %list  ) {
            push @{$list{$m}}, $ret*$m;
        }
        return $ret;
    };
}

@ARGV= (2,3,5)   if  ! @ARGV;
my $iter= gen(@ARGV);
print $iter->(), $/   while 1;

Ever notice that converting a functional program to a procedural one is a bit like doing a Fourier transform? (: I supposed I shouldn't be using a closure with such a claim, but they make convenient one-method objects.