Make Optional an IterableOnce

[guizmaii]

So that we can:

def get(a: A): Optional[B] = ...
val list: List[A] = ...
val result: List[B] = list.flatMap(get)

TODO:

• Fix 2.12 compilation

[sideeffffect]

I thought Option(al) as Iterable is controversial https://www.wartremover.org/doc/warts.html#option2iterable

But if you really know what you're doing and want it, then I'm not adamantly opposed.

[sideeffffect]

Why not Iterable?

[ghostdogpr]

The goal was to make a Chunk[Optional[A]] behave the same way as a Chunk[Option[A]] where we can just use flatten or flatMap to get rid of the empty values. And those two methods require an IterableOnce.

[sideeffffect]

Fair enough, but the question still stands. Wouldn't it be better to extend Iterable since we're changing things anyway? Maybe there are other use cases which won't do with mere IterableOnce. Or do you think it will be more complicated?

[guizmaii]

Why not Iterable?

Because Option doesn't extend Iterable but IterableOnce 🤷‍♂️
I'm just copying Option code 🙂

[sideeffffect]

Ah, I see. Than that should be good enough for us too :)

[ghostdogpr]

Seems IterableOnce was added in 2.13, in 2.12 the signature of flatMap was:

final override def flatMap[B, That](f: A => GenTraversableOnce[B])(implicit bf: CanBuildFrom[List[A], B, That]): That

[guizmaii]

@ghostdogpr

Seems IterableOnce was added in 2.13, in 2.12 the signature of flatMap was:

Well, my solution is just to make it compile with Scala 2.12.
The .flatMap(optional) doesn't compile with Scala 2.12 but IMO that's good enough.
If someone complains, it'll be time to evaluate if the effort to implement it for Scala 2.12 is worth it.
I don't think anyone will complain

[ghostdogpr]

I think this is good enough, immediate benefits and minimal maintenance efforts.

[sideeffffect]

Nice, thanks guys 👏