Re: [Chicken-users] length performance

[Kon Lovett]

Lists are not the central datatype in Python that they are in LISPs  
(LISt Processor), like Chicken Scheme. Contructors & mutators operate  
much more frequently than (length). In my collection of Scheme code  
(3396 files, not unique) it is used an average of once!

The requirement for O(1) (length) just isn't very common. In any case  
it is straightforward to code.

Best Wishes,
Kon


On Jan 4, 2006, at 9:56 AM, Mario Domenech Goulart wrote:

> Hello
>
> I've noticed that the performance of the length function is a bit low
> for medium/large lists.  As far as I understand (from runtime.c
> C_i_length), Chicken counts the elements from the given list everytime
> length is invoked.  Is it like that?
>
> If so, wouldn't it be better to have a list attribute which keeps the
> number of elements?  So, the cost of invoking length would be  
> nearly the
> cost of accessing a variable (of course, there is the cost of keeping
> the attribute up-to-date whenever an insertion/removal occurs and the
> memory usage).  I think Python uses this approach.
>
> What do you think?
>
> Best wishes.
> Mario
>
>
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