> * is it written somewhere in the specs, that eq returns empty sequence
> when some of the operands is an empty sequence? I looked, but did not find
> it..

A lot of it is covered in this thread:

http://markmail.org/thread/ekut6nktcluxsnbg#query:+page:1+mid:htioi45g53pswcv2+state:results

In summary it covers why:

() eq () returns ()

() = () returns false

deep-equal((), ()) returns true


-- 
Andrew Welch
http://andrewjwelch.com