Use Nothing for no Result - #52
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This is the best minimization I've found so far: class LambdaSuite {
def lambda[F[_]]: Resource[F, Lambda[F, Unit, Nothing]] = ???
def middleware[F[_], Event, Result, Env](lambda: Resource[F, Lambda[Kleisli[F, Env, *], Event, Result]]): Resource[F, Lambda[F, Event, Result]] = ???
implicit val nothing: Encoder[Nothing] = _ => ???
class NothingLambda extends IOLambda[Unit, Nothing] {
def handler =
middleware(lambda[Kleisli[IO, Unit, *]].mapK(Kleisli.applyK(())))
}
}It doesn't matter if the value passed to |
Co-authored-by: Brian Holt <bholt@dwolla.com>
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@bpholt thanks! That's an excellent minimization, exactly what I was looking for :) Unfortunately, placing the |
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Darn, 2.12 seems to be lacking. Dare I say ... we drop it? 😆 |
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Dropping 2.12 seems reasonable to me. I don't think the common reasons why people are stuck on 2.12 would apply in this context. |
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Yeah, apparently we are "future-forward" or something 😆 If it becomes an issue we can probably bring back 2.12 very easily anyway. Those users would just need to explicitly import this implicit and we'd need to make this test 2.13/3.x-only. FTR if sbt supported this config out-of-the-box that's exactly what I would have done. |
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Ummm ... Scala 3 is broken too? Seems like a compiler bug 🤔 Update: tracking in scala/scala3#13981. |
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tl;dr but I like the idea of |
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@kubukoz you're not stuck on Scala 2.12 are you? The tl;dr here is mostly about implicit scope for |
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I'm on 2.13, |
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Try |
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man, I can only have one experimental branch in my dependencies at a time 😂 |
| * userland code returns `Some`. | ||
| */ | ||
| @nowarn("msg=dead code following this construct") | ||
| implicit val nothingEncoder: Encoder[INothing] = (_: INothing) => ??? |
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not 100% sure but can't this just return its argument? (a: INothing) => a. INothing <: Nothing and Nothing <: Json.
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Good idea, this does work :)
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Actually you should have this in your branch, it's split off :) |
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we're reaching levels of stable that shouldn't be possible! |
| def middleware[F[_], Event, Result](lambda: Lambda[Kleisli[F, Unit, *], Event, Result]) | ||
| : Resource[F, Lambda[F, Event, Result]] = ??? | ||
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| class NothingLambda extends IOLambda[Unit, INothing] { |
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if I'm not mistaken this should even work with just Nothing, at least on 2.13
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This seems mergeable as well... |
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Yep, I'm just dealing with the conflicts rn :) |
3 participants
Based on #51.
@bpholt Before cherry-picking 00eb18f I wanted to try and write a test in 06c9eee that demonstrates the compiler issue with
Nothing. I tried replicating your example from #45 (comment) but didn't have much luck. When you have chance would you mind poking at this? Thanks :)