Re: Problem with position and find (cl)

[Barry Margolin <barmar@alum.mit.edu>]

In article <87abhfg0mn.fsf@sophokles.streitblatt.de>,
 Florian Beck <abstraktion@t-online.de> wrote:

> Thierry Volpiatto <thierry.volpiatto@gmail.com> writes:
> 
> 
> > position default test is 'eq, try 'equal
> 
> Indeed, many cl-tests default to 'eq.
> 
> BTW, what is the reason for this (apart from being a language convention)?

Just because things look similar doesn't mean they're the same.  Imagine 
if you use a list like (firstname lastname) to represent people, and you 
have two John Smiths in the group.

> 
> When I try
> 
> (let ((start-time (current-time)))
>   (dotimes (i 1000000)
>     (position '(1) '((2) (5) (2) 2 x  4 fer fer f r e wqf (1) fr r) :test 
>     'eq))
>   (format-time-string "%S" (time-since start-time)))
> 
> with 'eq and 'equal I get the same result. So 'eq is not more efficent,
> is it?

For a single-element list the difference is almost negligible.  Try 
again with long lists, like 50 or 100 elements long.

-- 
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***
*** PLEASE don't copy me on replies, I'll read them in the group ***