Proof of concept - library AA

[IgorStepanov via Digitalmars-d]

On Saturday, 30 May 2015 at 08:51:31 UTC, Vladimir Panteleev 
wrote:
> On Saturday, 30 May 2015 at 08:50:21 UTC, Vladimir Panteleev 
> wrote:
>> http://localhost/post/asvcbsvfcxznwypttojk@192.168.0.1
>
> Sorry, working link: 
> http://forum.dlang.org/post/asvcbsvfcxznwypttojk@192.168.0.1

We may say that AA!(K, V)* should be recognized as V[K] by 
compiler. However in this case we will found another problem: 
opIndexAssign will unable to allocate memory for the new AA 
instance, because it can't modify `this` pointer.
Otherwise, implicit casting _from_ another type is a unsolvable 
task now.
Please, remind, why we don't want to add possibility of implicit 
casting from another type (not as default constructor behaviour, 
of course)?
Something like

struct Foo
{
     int a;
     static Foo opImplicitConstructFrom(T)(T val) if(is(T : int))
     {
         return Foo(val);
     }
}