eqwalizer VS purerl

I don't think the implementation itself is at fault, but yes, I do think that the design of dialyzer makes it an (at times) faulty type checker. The unfortunate reality of a type checker that fails sometimes is that it makes it mostly useless because you can never trust that it'll do the job.

To be clear, I've had it fail in a function where I've literally specced that very function to return a `binary` but I'm returning an `integer` in one of the cases. This is a very shallow context but it can still fail. Now add more functions, maybe one more `case`.

I think an entire rethink of type checking on the BEAM had to be done and that's why eqWalizer[0] was created and why Elixir is looking to add an actual sound, well-developed type checker. Gleam[1] I would assume is just a Hindley-Milner system so that's completely solid. `purerl`[2] is just PureScript for the BEAM so that's also Hindley-Milner, meaning it's solid. `purerl` has some performance issues caused by it compiling down to closures everywhere but if you can pay that cost it's actually pretty fantastic. With that said my bet for the best statically typed experience right now on the BEAM would be `gleam`.

0 - https://github.com/WhatsApp/eqwalizer

1 - https://gleam.run

2 - https://github.com/purerl/purerl

While it's not static-typing, compile-time type checking for Erlang have come a long way: Eqwalizer works pretty well - but I may be biased since my employer sponsors the project.

1. https://github.com/WhatsApp/eqwalizer

Note there is also research happening in this area by the Elixir team. The WhatsApp is also working on static types for Erlang, which I am certain will be available for Elixir too at some point.

From the discord blog posts it seems that elixir powers the chat system, with rust and python as the other two main languages in their stack.

As for whatsapp, they are mainly a erlang shop and yesterday they open sourced a type checker for erlang:

https://github.com/WhatsApp/eqwalizer

I will put in a good word for PureScript for the beam with `purerl`. It's my go-to for writing BEAM code nowadays. Notably PureScript tooling including LSP, package management, etc., just works, so you are able to just get to work in internalizing the way OTP and other Erlangy things are expressed in a statically typed, pure language.

https://github.com/purerl/purerl & https://purerl-cookbook.readthedocs.io/ for more information. Join the PureScript discord and the #purerl channel if you want help.

purerl is a compiler for turning PureScript code into Erlang code, so that you're able to write BEAM (the Erlang virtual machine) applications using it.

You've been able to write PureScript that compiles to Erlang and has perfect interop for years, via `purerl`[0]. Using it with Elixir is as simple as adding `purerlex` as a compiler and having your PureScript code automatically compile when `mix` compiles things, and off you go.

In terms of the typing itself, it's exactly what you get in all of PureScript, strict static typing with no `any` or the like. Using `Pinto`, the de facto OTP layer in PureScript your processes are typed, i.e. their `info` messages & state are typed, which means that they are all much more like strongly typed state machines than anything else.

You can see an example of a basic `gen_server` here:

https://pastebin.com/UTEfz7Wg

The differences aren't very big in terms of what you'd expect to be doing. One small thing to note is that the `GenServer.call` expects a closure to be passed instead of having the split between `gen_server:call` & `handle_call`, removing the need for synchronizing two places for your messages being sent and handled.

0 - https://github.com/purerl/purerl