So I've got a general design question. Right now, ...

# coroutines

[groostav]

So I've got a general design question. Right now, at any moment, our callstack looks something like this:

com.mycompany.OurJavaAndKotlinFrontend.kt:123
sun.jna.proxies
SuperSecretCompanySauce.f99:1234 // yeah thats fortran code
sun.jna.proxies.callback
com.mycompany.OurJavaAndKotlinCallback.kt: 345

now if we assume the three bits of code we control apply transforms A -> B, B -> C, and C -> D respectively --and are all pure and referentially transparent and what not-- can I refactor our existing flow to use co-routines such that that C->D transform is factored out and expressed by the caller,so that the OurJavaAndKotlinCode class contains two methods: fun generatePartOne(a: A): C and setResult(d: D):Unit

To rephrase: right now the OurJavaAndKotlinFrontend class contains a method called fun doWork(input: Input): Output. It calls our fortran code, converting input into an intermediary that our native code can work with. Our native code then calls our JavaCode through a callback. The implementation of that callback was trickey, and I dont want to tamper with it or refactor the sturcture.

What I want is that when the fortran code calls back into kotlin with the argument nativeInfo, the current callback is suspended and a 'return' is made to the caller of KotlinFrontend with the value nativeInfo. The caller would do his own processing of nativeInfo, converting it into some other object, and then call back our frontend via some method setResult(convertedNativeInfo: Something), which would then resume the native code, passing control flow back to fortran.

I'm pretty sure this is achievable with a co-routine, im just not sure what the semantics are and how I would make all of this work under IOC, and with regular threads/executors.

Anyone know for certain this is achievable, and how I might go about implementing it? Blog posts much appreciated, even if they use C# verbiage.