I dun a DIP, possibly the best DIP ever

[Mafi]

On Thursday, 23 April 2020 at 15:11:16 UTC, Stefan Koch wrote:
> On Thursday, 23 April 2020 at 15:06:51 UTC, Mafi wrote:
>> On Thursday, 23 April 2020 at 12:43:59 UTC, Simen Kjærås wrote:
>>>[...]
>>
>> I think ...-Expressions should first expand nested 
>> ...-Expressions (or equivalently explicitly ignore nested 
>> ...-Expressions). Then the cross-product can be expressed as:
>>
>> template crossHelper(F, X, Y...) {
>>   alias crossHelper = F(X, Y)...;
>> }
>>
>> crossHelper!(S, X, Y...)...
>>
>> => S!(X[0], Y[0]), S!(X[1], Y[0]), ..., S!(X[n-1], X[m-1])
>>
>> because the nested expression Y... is expanded first resulting 
>> in crossHelper!(S, X, Y[0]), ..., crossHelper!(S, X, Y[m-1]) 
>> which then has the X expanded.
>
> that won't work.
> F is a type parameter in crossHelper.

Well, then what about:

template crossHelper(alias F, X, Y...) {
   alias crossHelper = F!(X, Y)...;
}

crossHelper!(S, X, Y...)...