Sum Types - first draft

[Walter Bright]

On 9/10/2024 10:23 AM, Paul Backus wrote:
>> I was approaching it from the other way around. Isn't a non-nullable pointer a 
>> sumtype? Why have both non-nullable types and sumtypes?
> 
> You have it exactly backwards. A _nullable_ pointer type is the sum of a 
> non-nullable pointer type and typeof(null).

"is the sum of..." makes it a sum type, doesn't it?