[Pitch] 128 bit Integer Types

[Joe_Groff]

@wadetregaskis

I think the main issue with that is that it turns trivial assignment into something that can crash, e.g. if you write powerLevel = 9001.

If you're forcing the type conversion onto your clients, then a crash is still there when they write powerLevel = UInt16(someInteger) or something like that. Maybe a developer could use one of the other non-trapping constructors but I doubt they would in practice. Trapping when preconditions are unmet is usually the right thing to do.

@tera

How can I make a 1 byte struct like Int8, and optional of it that doesn't add another byte?

The supported way would be to define an enum with fewer than 128 cases. The less-supported way would be to -enable-experiment-feature BuiltinModule and wrap the Builtin.Int7 type in a struct.