Re: Optional and NotNull version 0.5.0 - swift optional like and scala option like

[aliak via Digitalmars-d-announce]

On Wednesday, 22 August 2018 at 22:49:52 UTC, Paul Backus wrote:
On Wednesday, 22 August 2018 at 22:11:05 UTC, aliak wrote:
On Monday, 20 August 2018 at 19:52:53 UTC, jmh530 wrote:

It's interesting that both sumtype and optional have match 
templates. Maybe scope to combine these projects?

That'd be cool. Optional uses .match on a "some" or "none" 
range, while SumType uses it on a union. So ideas on how to go 
about it?

In theory, Optional(T) could be implemented as a wrapper around 
SumType!(T, None), which would let it reuse SumType's match 
method. I'm not sure if it'd be worth the effort to convert at 
this point, though.

THis is true. And might be interesting to try out actually. Can 
you access the types in a SumType via index?

I'm thinking because Optional behaves like a range, and I guess 
I'd define a SumType!(T, None), then a rough outline may be:

struct None {}
immutable none = None();

struct(T) {
  SumType(T, None) opt;
  T front() {
    return opt[0]; // what to do here?
  }
}

Or I guess I should maybe do it like this?:

return opt.match!(
  (T val) => val,
  (None) => T.init,
);