Joining array elements using a string is done in Ruby using the Array#join
method.
{{code:php $result = implode('; ', array('derek@example.com', 'mike@example.com')); var_export($result); // => 'derek@example.com; mike@example.com' }}
{{code:ruby p ['derek@example.com', 'mike@example.com'].join("; ") # => "derek@example.com; mike@example.com" }}
{{related: strings/explode }}