Feedback on Átila's Vision for D

JN 666total at
Wed Oct 16 07:09:38 UTC 2019

On Tuesday, 15 October 2019 at 16:17:57 UTC, Atila Neves wrote:
> Meh:
> //C++20 concepts
> concept isAddable = requires (T x) { x + x; };
> // D
> enum isAddable(T) = is(typeof((T x) => x + x));
> We lose by one character ;)

I disagree. It's not just one character. C++ example is much 
cleaner. Imagine not being experienced with C++ and D and seeing 
these two examples.

C++ line of thought: we're defining a concept isAddable, which is 
something that requires that there is some x that can be added to 

D line of thought: we're defining an enum (why enum? why would I 
want an enumeration here?) isAddable of type T which is something 
that is a typeof (wait, why do I have to repeat the T here 
again)?? What does that even mean "is(typeof())"?

It feels more complicated for a bystander. Actually, 
__traits(compiles) would be even cleaner in this case, because 
the is(typeof()) part, while could be considered a D idiom, feels 
very unexpected.

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