Should we add `a * b` for vectors?

[Petar]

On Wednesday, 4 October 2017 at 17:56:16 UTC, Walter Bright wrote:
> On 10/4/2017 2:28 AM, Dukc wrote:
>> But you can't deny our solution eats expressive power: If you 
>> don't want to change code you're importing, you have to write 
>> a wrapper type for int[] here.
>
> Please present an example.

I think that was the point of Timon's example. If you have a 
module A that implements a range algorithm, a module B that 
defines a range-like type (but actually its member function not 
matching the exact signature of range primitives), you (module C) 
as user of modules A and B are not able to provide range 
primitive wrapper functions for the type defined in module B 
(which you can't modify). So you can't use A's range algorithm on 
type defined in B.

ADL solves this problem (adapting third-party libraries to your 
needs).

Since D's modules are closed (can't be extended from the outside 
like namespaces), if we want to support some form of ADL (the 
primary use-case being algorithm libraries), we would probably 
need to introduce some form of open for extension scopes like 
namespaces. Or change extern (C++, namespace) to behave like 
people coming from C++ may expect.