variant visit not pure?

[Ben Jones]

On Thursday, 7 May 2020 at 14:53:10 UTC, Steven Schveighoffer 
wrote:

> As others have recommended, I suggest using TaggedAlgebraic. I 
> recently have been using it to create an algebraic type to hold 
> a MYSQL value, so I can migrate the mysql-native library to be 
> @safe (mysql-native currently uses Variant for everything).
>
> -Steve

I've been using SumType... What are the main differences between 
it and TaggedAlgebraic?