[swift-evolution] [Pitch] Ban the top value in Int/UInt / use smaller Integer

[Martin Waitz]

Hello,

> It's just that a common data type wasting almost half the space seems 
> inefficient. I guess this is also the reason why they didn't adopt 
> optional integers widely in stdlib.

When someone is really interested in fitting an optional integer into 
one machine word,
then the best way would be to use a smaller integer type (e.g. Int32 
instead of Int64).
These also can be mapped well into Enums (a single reserved value does 
not help at all here).

There are some almost 64-bit integers (Builtin.Int60 .. Builtin.Int63).
Maybe something like this could also be provided for normal use?

-- 
Martin