Discussion Thread: DIP 1037--Add Unary Operator ...--Community Review Round 1

[Steven Schveighoffer]

On 10/30/20 2:29 PM, Andrei Alexandrescu wrote:
> On 10/29/20 9:48 AM, Steven Schveighoffer wrote:
>> And a type can appear in an expression, as a template parameter:
>>
>> alias everyOther = AliasSeq!(0, 2, 4);
>>
>> alias everyOtherType = (AliasSeq!(int, uint, char, byte, ubyte, 
>> int)[everyOther])...;
>>
>> I think the DIP is intending for staticMap to be wholesale replaced 
>> with this, and seems to be saying this to me. I don't understand the 
>> above complaint, and why static map wouldn't work with types.
> 
> What would the implementation of staticMap with the DIP look like? As 
> far as I can tell from the DIP it cannot be done.

It has the implementation right in the DIP:

alias staticMap(alias F, T...) = F!T...;

>> Perhaps it's simply vocabulary that is the problem?
> 
> May as well. The way the DIP is written, there's no discussion of tuples 
> containing anything else but values.

In the examples there are. e.g.:

alias Values = AliasSeq!(1, 2, 3);
alias Types = AliasSeq!(int, short, float);
pragma(msg, cast(Types)Values...);

 > cast(int)1, cast(short)2, cast(float)3

Maybe it's not as clear with terminology. In some places it talks about 
tuples and their "elements", and in others, it talks about "values". I 
don't think it ever specifically talks about types in the description.

-Steve