thanks. I'm just trying to port that `ObjectPool` ...

# coroutines

[vaskir]

thanks. I'm just trying to port that ObjectPool from Hopac (to see whether it will be easier to understand). I'm inlining that functions into the main select, looks ok. Another problem is porting the Nacks. As I understand, coroutines do not support them? In short, a Nack is a alternative that becomes available for synchronization when client code's select does not select the alternative which this Nack is bound to. So I ported this function:

reqCh ^=> fun (nack, replyCh) ->
    let ok available instance =
        replyCh *<- Ok instance ^=>. loop (available, given + 1u) <|>
        nack ^=>. loop (instance :: available, given)
    match available with
    | instance :: available -> ok available instance
    | [] -> try createNew () |> PoolEntry.Create |> ok available
            with e -> (replyCh *<- Fail e <|> nack) ^=>. loop (available, given)

to this select branch:

reqCh.onReceive { (nack, replyCh) ->
    if (available.empty()) {
        try {
            val instance = PoolEntry(createNew())
            select<Unit> {
                replyCh.onSend(Ok(instance)) { given++ }
                nack.onSend(Unit) { available.add(instance) }
            }

        } catch (e : Throwable) {
            select<Unit> {
                replyCh.onSend(Err(e)) {}
                nack.onSend(Unit) {}
            }
        }
    }
    else {
        val instance = available.pop()
        select {
            replyCh.onSend(Ok(instance)) { given++ }
            nack.onSend(Unit) { available.add(instance) }
        }
    }
}

https://github.com/Hopac/Hopac/blob/master/Docs/Programming.md#negative-acknowledgments
I'm not saying Kotlin must support nacks, just asking if ^^^ make sense.