Is there an easy way to mimic generics with an accept method of a visitor pattern?

[vitamin]

On Thursday, 18 February 2021 at 15:11:44 UTC, Paul Backus wrote:
> On Thursday, 18 February 2021 at 14:51:09 UTC, vitamin wrote:
>> On Thursday, 18 February 2021 at 14:43:43 UTC, Paul Backus 
>> wrote:
>>>
>>> I don't see what this buys you compared to sticking with one 
>>> or the other, but you are correct that it is technically 
>>> possible.
>>
>> It infer function atributes (pure, nothrow @nogc @safe) for 
>> "visitor" and let you use classes and inheritence.
>> With standard visitor pattern you need PureVisitor. 
>> NothrowVisitor, PureNothrowVisitor...
>
> It seems to me like you would also get those benefits by just 
> using a discriminated union, without the classes.

Yes, but classes has nice things like abstract/override/final 
methods and covariant return types and almost everybody known how 
they works. Maybe this things can be simulated with templates.