Proposing std.typecons : Optional (with PR)

[FeepingCreature]

On Wednesday, 12 June 2019 at 09:53:03 UTC, Jacob Carlborg wrote:
> On 2019-06-11 15:55, FeepingCreature wrote:
>
>> We have "map for Optional/Nullable", that's `apply`.
>
> And the rest of the algorithms?

As the saying goes, "PRs welcome." Personally I get along fine 
without them, so I didn't see the need to include them. For 
instance, we have a local orElse implementation hanging around. 
The point of having `Optional` in the stdlib is that the rest of 
the ecosystem can standardize around the data structure. There is 
none such need for algorithms, especially oneliners.