[OT] ISO C++ 17 changes

[Meta via Digitalmars-d]

On Monday, 3 April 2017 at 21:33:20 UTC, Timon Gehr wrote:
> On 03.04.2017 20:24, Meta wrote:
>> On Monday, 3 April 2017 at 08:53:57 UTC, Andrea Fontana wrote:
>>> https://isocpp.org/files/papers/p0636r0.html
>>
>> The fold expressions and inference of constructor template 
>> args look
>> very nice. C++ is quickly catching up to D in a lot of areas, 
>> although
>> usually still with worse syntax. I don't know how fold 
>> expressions could
>> be emulated in D.
>
> String mixins.

I try to avoid string mixins if possible as they're incredibly 
ugly. I did try hacking something together with templates and 
string mixins, though, but could not get it to work. I stopped 
here:

template fold(string op, Args...)
{
	static if (Args.length == 1)
		enum fold = Args[0];
	else
		enum fold = mixin("Args[0] " ~ op ~ " fold!(op, Args[1..$])"); 
//variable _param_2 cannot be read at compile time
}

auto f(Args...)(Args args)
{
	return fold!("+", args);
}

void main()
{
	assert(f(1, 2, 3) == 6);
}

Any suggestions as to how to get something similar working?