Hi, let's say I'd want to use `either { ... }` com...

# arrow

[Jörg Winter]

Hi, let's say I'd want to use either { ... } computation in a conventional (non-reactive, controller endpoints are not suspend!) Spring Boot RestController (for validation + effect-short-circuiting)
... what are my options: runBlocking, or some other recommended 'bridge to suspend-world' ?
Obviously this concern could become obsolete if mainstream actually moves away from 'blocking Spring', but what recommendations (if any specific exist) are there until then ?

[simon.vergauwen]

Hey @Jörg Winter,

There is also either.eager which works with @RestrictSuspension and works for normal eager code.
It also dissallows foreign suspend code so in contrast to either you cannot do the following.

suspend fun mySuspend(): Unit = TODO()

suspend fun example1(): Either<String, Unit> = either {
  mySuspend() // Works fine
}

fun example2(): Either<String, Unit> =
  either.eager {
    mySuspend() // Won't compile
  }

fun normalFunction(): Unit = Unit

fun example3(): Either<String, Unit> =
  either.eager {
    normalFunction() // Works
  }

[simon.vergauwen]

We had to make a distinction in name due to conflicting signatures otherwise 😞

[simon.vergauwen]

The eager version is also available for nullable, option etc if you need it 🙂

[Jörg Winter]

Thank you, will try this 🙂

[Jörg Winter]

..and likewise for Validated and Either types I guess (not just Unit)
With this there is no messing around with thread-pools in a non-reactive backend, nice

[Jörg Winter]

And we can of course import arrow.core.computations.either.eager as doEither and it looks nice enough