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Comment by floodfx | Hacker News Reader

I think it is more exciting and more innovative to think about LiveView as a new architectural approach to building reactive applications. Yes in Elixir land it is a Process and there are some amazing things about the BEAM. But LiveViews have the potential have an impact beyond just the Elixir ecosystem and folks should embrace that.

I’ve been a part of porting the Phoenix LiveView Protocol to both Javascript (https://LiveViewJS.com) and Go (https://github.com/canopyclimate/golive) backends and supported a friend that is porting it to Python.

Ironically I think taking LiveViews outside of Elixir could actually make it easier for folks to adopt Elixir-based LiveViews in the future.

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Porting this is cool but why would people adopt Elixir if they can have LiveViews in their preferred language?

Ergonomics matter.

Because outside of Go (and maybe Rust) it will be very difficult to actually do what Elixir does, with the same level of concurrency and fault tolerance, etc, with the same ergonomics.

Ruby/Rails/StimulusReflex does something very similar, but kind of falls over unless you replace ActionCable with AnyCable which is written in Go.

So now, you have to support Go and Ruby runtimes. Some developer who decided that the above was a nightmare to work with, __might__ start a new project in Elixir, to get something that actually does what Elixir does instead of just mimicking it.

I'm not sure I buy this, personally, but I can understand the argument.

> Because outside of Go (and maybe Rust) it will be very difficult to actually do what Elixir does

It's just as difficult in Go and Rust. BEAM, the Erlang VM that powers Elixir, is not just about lightweight processes. It's also about guarantees that neither Go nor Rust provide. E.g. to do what Elixir does you need robust process supervision trees. You can imitate, but not replicate those in other languages.

Virding's Law: Any sufficiently complicated concurrent program in another language contains an ad hoc informally-specified bug-ridden slow implementation of half of Erlang.

Comments like this push people away from Erlang rather than draw them in.

I find it quite the opposite: what is it that other languages are trying to re-implement, and why they can't?

It's a play on https://en.wikipedia.org/wiki/Greenspun%27s_tenth_rule

And yet it doesn't matter.

It should.

Then in the vast majority of cases we wouldn't run kubernetes clusters running docker containers for one-off tasks and single services. Or "serverless functions".

Unfortunately even the otherwise very smart folks of Go and Rust only see "ah, lightweight threads, got you". That's why, for example, you get irrecoverable panics in both languages and awkward attempts to patch over them in later versions.

Meanwhile Armstrong's thesis "Making reliable distributed software in the presence of hardware/software errors" is over thirty years old now.

> It should

Should it?

> otherwise very smart folks of Go and Rust

Ahh, everyone else is wrong. Gotcha. RabbitMQ is life(LOL), god save the BEAM!

In Go you’d run a goroutine and then send either a result or an error over a channel. I’m curious what else would be needed for “robust” supervision of the goroutine like Elixir/Erlang? I haven’t really felt a need for anything more.

What happens when a channel abruptly closes? Or when it throws an error?

Erlang VM guarantees that [1]

- all processes are isolated. Fatal error in one process will not affect other processes. Crucial: it will not affect the VM.

- If you set up process monitoring, and that process dies for whatever reason the monitor will be notified, with the actual reason. This lets the monitor (the supervising process) decide what to do next: restart, do nothing, stop entirely etc.

- Other relevant things like processes suspended when waiting for messages, or running out of reductions (number of allocated calls and messages) so that other processes can be executed, a bunch optimizations in the VM about CPU caches etc.

So what you have is "kubernetes for processes, inside the VM".

And the reason you don't have supervision for either Go or Rust is simple. Both Go and Rust for some completely asinine reasons decided that an unhandled error should kill the entire running application, with no chance of recovery.

And later they both awkwardly bolted on a half-assed solution to catch panics. That's it. That's the extent of error handling and guarantees in those languages. Of course no one builds supervision trees there.

[1] Of course it's not a 100% guarantee, nothing is, but other languages don't have even that.

Thanks for the explanation. I see your point about panics, though using panics is rare in Go and not what would normally happen in a goroutine that has an error. If you know your goroutine won’t panic, getting the result or error from a channel seems sufficient in most cases, but it’s true that you can’t always know that.

The problem isn't about using panics, or "knowing that your goroutine won't panic". Things happen. Unhandled errors happen. Unhandled errors from processes happen :)

Erlang'd documentation used to have a section called "Do not program defensively" [1] This is known as "let it crash" philosophy. Or, better put, that Erlang has auto healing mechanisms [2]

When applied correctly, it significantly reduces the amount of boiler plate code you need to write because you're only concerned with the happy path in most of your code.

[1] A copy is available here: https://docs.jj1bdx.tokyo/Erlang_Programming_Rules.html#HDR1...

[2] Erlang has auto healing mechanisms

If you look at my comment history, you'll see I'm well familiar with the BEAM.

I'm in full agreement with you, but I'm not sure you need full robust process supervision trees to mimic what the BEAM does in the context of LiveView on a single machine.

I do want to say, I 100000% times prefer Elixir, it's tooling, ecosystem, web frameworks, easy of scaling vertically and horizontally, etc over Go or any other lang that probably do something analogous to LiveView via what ever concurrency primitives that language/runtime champions; Go with it's Communicating sequential processes(CSP) and Rust with the Ractor lib (https://github.com/slawlor/ractor).

Understanding LiveViews as a concept could make it easier to commit to learning a new language. I am not saying one should but that one could and it would probably be easier since you don't have the additional overhead of also learning what is a LiveView.

Same reason why people may get hooked on some fp library can lead to them trying Haskell.

Is your friend's python library open source by any chance? I was thinking about doing the same.

https://github.com/ogrodnek/pyview

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