Hi, 

In message "[ruby-talk:9082] Re: Regexp for matching Ruby reg exps?"
    on 01/01/11, "Ben Tilly" <ben_tilly / hotmail.com> writes:
>>Ruby's regexp is extended rather than the theoretical one.
>[...]
>
>For those who don't understand what he meant, the theory
>of regular expressions started with a theory of finite
>state engines.  The finite state engine approach (used in
>grep for instance) gives limited functionality but also
>can determine whether or not there is a match very
>efficiently.

Thank you for kind explanation, Ben.  

Reading your comment, I remember an idea on Array#===.  As you know,
=== is designed for case-when.  Several years ago, I thought === can
be considered as membership test.  But only Array#=== seems to break
this prediction.  I hope Array#=== would be aliased to include?.  
What do you think?

-- Gotoken