A little challenge...

[Norbert Nemec]

Ary Borenszweig wrote:
> Norbert Nemec wrote:
>> Hi everybody,
>>
>> thinking about array expressions, I have stumbled over an interesting 
>> challenge for which I still have no idea:
>>
>> Consider the mathematical sum notation:
>>
>>     \sum_i a_i*b_i
>>
>> here, the variable i is defined only at the scope inside the expression.
>>
>> A analogous D syntax could be something like
>>
>>     sum!(i)(a[i]*b[i])
>>
>> where sum would have to be some kind of template that takes i as a 
>> name parameter and then defines it as variable inside the scope of the 
>> second expression.
> 
> You are missing i's initial and ending values.
> 
> I think it should be something like:
> 
> sum!("i", 0, n)(a[i]*b[i])

I assumed them to default to the array boundaries, but that does not 
really matter at this point.