Re: vectors are something else

[Daniel Hartwig]

On 15 April 2013 22:08, Daniel Llorens <address@hidden> wrote:
>
> On Apr 15, 2013, at 14:28, Daniel Hartwig wrote:
>
>> Is it
>> really much faster to do one or the other:
>>
>> if lbnd != 0: error
>> index = …
>>
>> vs:
>>
>> index = lbnd + ...
>
> The second should actually be just
>
> index = ...
>
> You do this by having the base index point to the element at index 0
> and not to the first element. This is a mistake all through the Guile
> array code.

So lbnd is only for range checking.  Neat.

>
> A branch would certainly be slower. However, if the array implementation
> was exposed to the compiler, the lbnd!=0 check could be hoisted out of
> any array loop. So both would end up being identical in that case.

I see.