For a Perl web application I'm working on, I'm wanting a function which merges 2 strings (scalars containing any ASCII 0-255 chars) like a zip, i.e. 1 char from each string until the 2nd string (which will be always shorter) runs out, at which point the rest of the 1st string is returned as is.

For example, calling:
   zip("ABCDEFGHIJ", "abcde");
would return
   AaBbCcDdEeFGHIJ

I've just written such a function (below) which does the job, but I know TIMTOWTDI and I'm hoping there's a more concise/elegant way.  Can any of you suggested more concise, elegant & efficient code?

#!/usr/bin/perl

print zip('ABCDEFGHIJ', 'abcde') . "\n";

sub zip
{
  my ($str1, $str2) = @_;
  my $zip;
  for (my $i=0; $i<length($str1); $i++)
  {
    $zip .= substr($str1, $i, 1);
    if ($i < length($str2))
    { $zip .= substr($str2, $i, 1) }
    else
    {
      $zip .= substr($str1, $i+1);
      $i = length($str1);
    }
  }
  return $zip;
}
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