RT/CT Type

[Alex]

On Tuesday, 2 April 2019 at 10:45:37 UTC, Jacob Carlborg wrote:
> On 2019-04-02 09:48, Alex wrote:
>> Since D has a highly evolved meta programming and it should 
>> have unitifed type that works two ways:
>> 
>> 1. At CT, the type acts as an type or sorta like an alias.
>> 2. At RT the type acts as a string.
>> 
>> Type t = int;
>> 
>> At compile time,
>> 
>> t x;
>> 
>> is the same at
>> 
>> int x;
>> 
>> 
>> At RT t = "int"
>> 
>> 
>> Why is this important?
>> 
>> 
>> The purpose is to unify certain CT and RT code. Because CTFE 
>> acts as runtime we might use it to build a type, but as a 
>> string, such as
>> 
>> return getType(T)(T x)
>> {
>>      return T.stringof; // CTFE/RT
>>      //return T // would be simpler
>> }
>> 
>> But then we could do
>> 
>> getType(32) x;
>> 
>> at CT.
>> 
>> or use getType at runtime.
>> 
>> This is a contrived example but I'm finding that I'm having to 
>> use CTFE to deal with types which requires strings and then 
>> convert those strings back in to types using string mixins, 
>> which is a PIBA.
>
> I would much rather that D had first class types. That is, it 
> would be possible to store types in variables and in arrays and 
> so on.

Sure, but that isn't likely to happen and probably will be far 
more work. By simply having them convert to strings in RT helps a 
lot. When combined with CTFE and mixins it works well because one 
can go back and forth between type and strings.