PLAN: Purely Functional Programming With Batteries Included by Jack Ek at #LambdaConf2024

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PLAN is a new VM based on established technology which allows programmers to write functional programs with automatically persisted state which is portable across architectures. Programming languages today tend to run in stateful environments, which imposes an impedance mismatch on purely functional languages. Instead of adapting the language to the environment—introducing impurity, whether directly or managed through an IO monad—we suggest adapting the environment to the language and simply treat our main closure as our state, in the hope that this will make software simpler and more maintainable. The specification of the VM is both minimal and straightforward to implement performantly, while its native code format remains human-understandable. We use an immutable code sequence to bootstrap an extensible higher level language, which together with the runtime gives us a usable system in significantly less than 10k of non-golfed, zero-dependency and highly auditable LOC.