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kotlinlang

Hello, question from newbee. I would like to create a Kotlin subset that is resumable, i.e. whose internal state can be saved in a database at specific points in the code to be resumed later - perhaps on another machine. Will I have to rewrite everything, or are there parts I can reuse (beyond the grammar)?

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That's a fundamental part of a language, I only remember Apache Spark doing something similar in Scala, and it required an unholy amount of black magic to make work - which is why they always lagged a language version behind the compiler to make it work.

You could probably rewrite it to some representation via KSP, and then evaluate that in a virtual machine you control.

Or take a look at Elixir which has these features built-in :slightly_smiling_face:

Looks about right: <https://chat.openai.com/share/2275953d-679e-47a6-b661-ca7af971e4c8>

You can expand current coroutines machinery - every suspend function has a continuation object, which (in theory) can be saved and restored on different machine. Be careful, though, since not everything is serializable.

So, in theory, there is a subset of Kotlin with only `@Serializable` objects and consisting only of suspend functions. The only thing you need is to write serialization/deserialization routines.

That’s the idea actually. Can you please point me out where I should start looking at?

In this subset, we would have only data coming from protobuf objects - hence serializable

<@U014DF0QJLC> Depends on your knowledge. Here is the section about variables spilling (saving to an object for you to parse) <https://github.com/JetBrains/kotlin/blob/master/compiler/backend/src/org/jetbrains/kotlin/codegen/coroutines/coroutines-codegen.md#variables-spilling|https://github.com/JetBrains/kotlin/blob/master/compiler/backend/src/org/jetbrains/kotlin/codegen/coroutines/coroutines-codegen.md#variabl[…]pilling>, you should save the state of the program in <https://github.com/JetBrains/kotlin/blob/master/compiler/backend/src/org/jetbrains/kotlin/codegen/coroutines/coroutines-codegen.md#suspendcoroutine> and then, after restoring the state, just call `Continuation.resume()` on the restored object.