draft proposal for Sum Types for D

[cc]

On Tuesday, 29 November 2022 at 06:26:20 UTC, Walter Bright wrote:
> Go ahead, Make My Day! Destroy!
>
> https://github.com/WalterBright/DIPs/blob/sumtypes/DIPs/1NNN-(wgb).md

I like the `a | b | c` syntax, because the simpler and cleaner it 
is to use a tool suitable for efficient expressive error 
checking, the more likely I'll be to *actually use it* to 
implement error checking.  The seductive alternative in my 
experience will always be "Ehh, error checking? What a hassle. 
I'll wrap everything in try/catch tomorrow... maybe."