sub combinations {
    my @list= @_;           # List of items to choose from
    my @pick= (0) x @list;  # Whether we want each item
    # $pick[$i] means include $list[$i] in results.
    # So @pick currently describes the empty subset.
    # Return a closure that, each time it is called, returns
    #   the next subset:
    return sub {
        # Treat @pick as a base-2 number and increment it.
        # Note that @pick started as all 0s and we stop
        #   after it is all 1s so all cases get covered.
        # (See original node for handling the empty subset)

        # Start at least-significant bit, $pick[0]:
        my $i= 0;
        # Increment a bit. If the bit was already 1, then
        #   set it to 0 and continue to next bit:
        while( 1 < ++$pick[$i]  ) {
            $pick[$i]= 0;
            # If we've run out of bits, then we were at
            #   all 1s and so are done. Return empty list:
            return   if  $#pick < ++$i;
        }
        # The grep() below returns the indices for which
        #   $pick[$_] is not 0.  The @list[...] is an array
        #   slice that returns the list of elements of @list
        #   at the indices returned by grep.  That is, we
        #   return all items $list[$i] where $pick[$i] is
        #   not 0.  Same as:
        #     map { $pick[$_] ? $list[$_] : () } 0..$#list;
        return @list[ grep $pick[$_], 0..$#pick ];
    };
}
my $next= combinations( 50..59 );
my @comb;
while(  @comb= $next->()  ) {
    # do work with @comb here
}
[download]

Does that help?