D compile time algorithms implementation

[khurshid]

On Saturday, 20 April 2013 at 11:07:28 UTC, Timon Gehr wrote:
> On 04/20/2013 08:07 AM, khurshid wrote:
>> I just have read from github  std.variant, std.typetuple, etc. 
>> source
>> codes.
>> And I have a question.
>> Why more linear algorithms implemented with O(N^2) ?
>> example: staticMap,  it doesnot compiled  more 500 arguments.
>> although, following version compiled for more than 32768 
>> arguments:
>>
>> template staticMap2(alias F, T...)
>> {
>>         static if (T.length == 0)
>>         {
>>                 alias TypeTuple!() staticMap2;
>>
>>         }
>>         else static if (T.length == 1)
>>         {
>>                 alias TypeTuple!(F!(T[0])) staticMap2;
>>         }
>>         else
>>         {
>>                 alias TypeTuple!( staticMap2!(F, T[0..$/2]),
>> staticMap2!(F,
>> T[$/2..$]))  staticMap2;
>>         }
>> }
>
> FWIW I think the O(N^2) behaviour is a limitation of the 
> compiler implementation (I think ropes might be a better data 
> structure than arrays to back compiler tuples.)

For using only one algorithm - it's no problem.

But if we are using algorithm inside another algorithm (like 
NoDuples(..) which  inside uses EraseAll ) - compile time will 
become very slowly.