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0 pointspdimitar5y ago0 comments

> But I'll never understand that people like Elixir for being FP.

To me the answer is: using mutable state is opt-in. I disagree that "mutable state is rampant".

By opting in to the mutable state constructs you are basically saying "I know what I am doing, let me do my work" which is IMO quite fine because "pure" FP languages like Haskell can be a huge hassle when you actually need to deal with the real world.

To me Elixir is a very nice compromise.

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senderista5y ago

Mutable state is essential to the actor model. Local arguments to a tail-recursive message loop which change based on the last received message and the previous arguments, and determine behavior (i.e. messages sent and side effects), are equivalent to local mutable state. State machines are a lot better than unstructured, freely mutable global variables, but they are still mutable state.

pdimitarOP5y ago

Sure. That's absolutely unavoidable in any FP language. All their compilers invisibly produce a lower-level code that's intrinsically using the mutable paradigm. It's how our hardware works currently.

eru5y ago

No, in an actor based model the mutable parts that the comment you replied to mentioned are surfaced to the user.

It's not about how the Erlang VM is implemented. You could implement it in pure Haskell and compile it so some hypothetical pure CPU. Wouldn't change that part of how you interact with it that is stateful as described.

(And I liked programming in Erlang.)

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