sumtypes for D

[deadalnix]

On Tuesday, 29 November 2022 at 06:45:37 UTC, Walter Bright wrote:
> Top level qualifiers can be removed with:
>
>     cast()expression

No, this will remove all qualifiers on user defined types. Which 
is one more reason one cannot provide a user defined type that 
behave like the builtin ones, and this is something you want to 
be able to do, for collections, ranges, as well as for sum types.