# # This software is Copyright 2005 by Elsevier Inc. You may use it # under the terms of the license at http://perl.plover.com/hop/LICENSE.txt . # ### ### interleave ### ## Chapter 7 section 3.1 sub interleave { my ($a, $b) = @_; return sub { my $next = $a->(); unless (defined $next) { $a = $b; $next = $a->(); } ($a, $b) = ($b, $a); $next; } }