I think I m already hitting the limits of the compiler Wrapp

Question

I think I m already hitting the limits of the compiler Wrapping an API into coroutines ```suspend fun lt ReaderType ReturnType gt registerCallback listener ReaderType gt Unit gt Unit func ReaderType gt ReturnType ReturnType return suspendCoroutine lt ReturnType gt block gt listener btr gt block resume func btr listener null val reader = registerCallback acsBluetoothReaderManager setOnReaderDetectionListener reader gt reader ``` gives me ``` java lang ClassCastException org reactormonk debugapplication BluetoothSupportKt$registerCallback$2$1 cannot be cast to com acs bluetooth BluetoothReaderManager$OnReaderDetectionListener at org reactormonk debugapplication BluetoothNFCActivity$onCreate$1$reader$1 invoke BluetoothNFC kt 72 ``` Compiles fine though This is the interface ``` public void setOnReaderDetectionListener BluetoothReaderManager OnReaderDetectionListener listener this b = listener public interface OnReaderDetectionListener void onReaderDetection BluetoothReader var1 ```

Grégory Lureau · Answer

Weird it should not compile afaik Your lambda is not actually implementing OnReaderDetectionListener so in `registerCallback` when you call `listener ` you implement a method with a signature that looks like the interface ORDL but is not an implementation of it and I think it matches the ClassCastException error You may try with a functional interface but I think it ll be the same issue eventually for the JVM build at least

Grégory Lureau · Answer

If you want to use lambdas why not removing the interface instead ``` public void setOnReaderDetectionListener listener BluetoothReader gt Unit this b = listener ```

Grégory Lureau · Answer

Also tbh I m not sure what you re trying to achieve with the registerCallback method thinking face

reactormonk · Answer

Can t modify that part of the code proprietary jar disappointed

reactormonk · Answer

It s a weird interface where you a gotta register a callback for when the hardware gets back to you that s the listener part b call the method The example here is only a this is the big brother ```suspend fun lt ReaderType InputType OutputType ReturnType gt convertToCallback funCall InputType gt Boolean listener ReaderType OutputType Int gt Unit gt Unit input InputType outputParser OutputType gt ReturnType ReturnType return suspendCoroutine lt ReturnType gt block gt if funCall input listener output errorCode gt if errorCode == 0 block resume outputParser output else block resumeWithException ReaderCommandException Error code from reader $errorCode listener null else block resumeWithException ReaderCommandException Couldn t send command Bonded ``` Yes I ve written Haskell professionally before Does it show This is the full selection of interfaces I m trying to abstract over ``` public interface OnEnableNotificationCompleteListener void onEnableNotificationComplete BluetoothReader var1 int var2 public interface OnResponseApduAvailableListener void onResponseApduAvailable BluetoothReader var1 byte var2 int var3 public interface OnEscapeResponseAvailableListener void onEscapeResponseAvailable BluetoothReader var1 byte var2 int var3 public interface OnDeviceInfoAvailableListener void onDeviceInfoAvailable BluetoothReader var1 int var2 Object var3 int var4 public interface OnCardStatusChangeListener void onCardStatusChange BluetoothReader var1 int var2 public interface OnCardStatusAvailableListener void onCardStatusAvailable BluetoothReader var1 int var2 int var3 public interface OnCardPowerOffCompleteListener void onCardPowerOffComplete BluetoothReader var1 int var2 public interface OnAuthenticationCompleteListener void onAuthenticationComplete BluetoothReader var1 int var2 public interface OnAtrAvailableListener void onAtrAvailable BluetoothReader var1 byte var2 int var3 ```

reactormonk · Answer

Maybe I m approaching this by shoehorning a specific way into Kotlin what would be a decent way to put some `suspend` into it