How do I correctly use `either {}` in combination with `flow {}` ? when I have a function like this...

# arrow

[S.]

How do I correctly use either {} in combination with flow {} ? when I have a function like this

fun list(): Either<Error, Flow<Item>> = either { 
    flow {
        if (someSuspendFun()) [e-mail](Error)
    emitAll(someList())
    }
}

it says arrow.core.raise.RaiseLeakedException: 'raise' or 'bind' was leaked outside of its context scope. Make sure all calls to 'raise' and 'bind' occur within the lifecycle of nullable { }, either { } or similar builders.
or is the way to go to make the function suspend and do the check before the flow block?

[simon.vergauwen]

Either needs to stay inside Flow, so Flow<Either<E, A>>, or you need to call collect inside either itself.

[S.]

I'm not collecting it here, just passing the flow on but would this then be okay

suspend fun list(): Either<Error, Flow<Item>> = either { 
if (someSuspendFun()) raise(Error)
someList()
}

or is Either<E, Flow<A>> a bad idea in general?

[simon.vergauwen]

No, that works great! It depends on your use-case to be honest.

This is perfect if constructing the Flow can go wrong, Flow<Either<E, A>> is great if you need to model error as part of your stream without stopping (Exception).

[S.]

alright, thanks! and yeah in that case I want to stop the entire request if permissions are missing