sumtypes for D

[Paul Backus]

On Tuesday, 29 November 2022 at 04:05:46 UTC, zjh wrote:
> On Tuesday, 29 November 2022 at 03:37:39 UTC, Paul Backus wrote:
>> because in the general case only the user has the knowledge 
>> necessary to establish the correspondence between a templated 
>> type's *structure* (e.g., "the head-mutable version of 
>> `const(Foo!T)`") and its *name* (e.g., `Foo!(const(T))`).
>>
>> The problem is, that solution has been declared categorically 
>> off the table, so we are stuck going in circles debating the 
>> merits and shortcoming of various half-measures.
>
>
> There are solutions, why not to apply it?
> D should not become a `religion`.

Walter Bright is strongly opposed to adding user-defined implicit 
conversions to D. You can search the forum for his posts on the 
subject; here is one example:

https://forum.dlang.org/post/rs9k19$1982$1@digitalmars.com