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Elixir v1.20: Now a gradually typed language

elixir-lang.org

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Re: Elixir v1.20: Now a gradually typed language

#281

Post by josevalim »

xlii wrote: post #278
josevalim wrote: post #266

Earlier quoted context omitted.

You are mixing runtime and compile-time dependencies. Runtime dependencies (circular or not) have no impact on compilation performance and stability. Phoenix does include one circular dependency (the layout is rendered by your endpoint and it references your endpoint) but it is a runtime one.

No I'm not. This is often brought up. I spent 3 months analyzing failures caused by - what looked like - dirty builds but was caused by unstable compilation order. Which is quite obvious. The solution is dynamic dependency resolution but this causes problem with macros. The problem is easy to validate. Compile application multiple time and compare hashes. I'm not sure if it's sufficiently visible in bootstrapped Phoe…

Please file a bug report if you can indeed isolate/reproduce it (and please ping me on GitHub once you do)!

Re: Elixir v1.20: Now a gradually typed language

#282

Post by josevalim »

osener wrote: post #280
josevalim wrote: post #271

Earlier quoted context omitted.

> Honest question, in the era of vibe and AI assisted coding is there any advantages of using untyped programming languages, apart from the fact that non-typed languages has more traning data for the LLM? Author here. Type systems restrict which programs can be expressed and increasing expressiveness often requires increasing type-system complexity (which, speaking from experience, both humans and agents will struggl…

In my experience restricting programs that can be expressed is a good thing, even more so with agentic engineering. The more guardrails there are, strong typing/TDD/computer use/..., the solution space shrinks and chance of a robust solution increases. Sure maybe this burns more tokens going in circles but it feels less like a slot machine more like a robot searching for a solution for a well-defined problem. Devs ha…

Agreed on the guardrails bit. My point is that we still don't have much evidence that static types are an effective way to constrain the search space for coding agents, or how much value they add on top of other mechanisms. Redundancy can certainly be beneficial, but how much and at what cost?

On expressiveness, people often frame it as a dynamic-language goal, but a large portion of type system research is precisely about making type systems more expressive so they can describe a wider range of programs and invariants. This is clearly something both camps value. I suppose another interesting benchmark could be: how do coding agents perform across languages with different degrees of type-system expressiveness?

We may directionally agree, but it is hard to draw conclusions without measurements. Overall, I'd say this is much more of an open question than people give it credit for.

Re: Elixir v1.20: Now a gradually typed language

#284

Post by sph »

steve_adams_86 wrote: post #245
neya wrote: post #241

Earlier quoted context omitted.

If you use Phoenix, using types at the data model level using changesets and then trickling them down all the way to the UI is a very good compromise. As changesets provide type validations out of the box too.

Do changesets incur a runtime cost?

Not sure what you mean here. Changesets are used to validate user input before interaction with business logic or your database; of course data validation has a runtime cost, in any language.

Please don't use changesets to enforce some kind of type system between system components. In case you do not trust your own code, Elixir is strongly typed (though not static typed), there are test cases, there's dialyxir and if still you cannot stop yourself from passing a number where a string will do, the process will crash, log a message for you to fix the bug, and get restarted by a supervisor.

I get why people are obsessed with static typing on "normal" languages, where bugs cause system downtime, but the Erlang platform gives you so many guarantees that even if you somehow make a mistake, it is never catastrophic. Gradual typing in Elixir is a nice cherry on top of the runtime, not the cornerstone to robust OTP software.

Re: Elixir v1.20: Now a gradually typed language

#286

Post by whstl »

galaxyLogic wrote: post #188
meghprkh wrote: post #172

Earlier quoted context omitted.

Not necessarily. Since the word "typed" language is not well-defined. For example, typescript is a fantastic language for marshalling data and UI state since it uses substructural typing instead of nominal typing. Libraries like kysely / other ORM libraries are great examples too and easy to use, whereas in fully typed languages like Rust you would end up having to use a macro library like sqlx or having to define st…

As I understand it TypeScript does not enforce types at runtime. Am I correct? If so that would signify to me it is not a "typed language", like say Java for instance. Types in TypeScript are more like "annotations" for docujmenting the program. Am I correct?

Lots (most?) of statically typed languages also do near zero runtime checking.

They naturally use types for compilation, but the type system is trusted to forbid some invalid states. Underneath it’s all bits and bytes.

Even in safe languages you need deserializers/parsers/validators.

Typescript actually ends up having more checks because it runs Javascript underneath (although some might argue those barely count).

Re: Elixir v1.20: Now a gradually typed language

#288

Post by sph »

losvedir wrote: post #88

Oooh, here we go! As a professional Elixir developer for... 10-ish years now, I've been super excited about types coming. I'm very excited that the beginnings have started to land here. That said, I would love to know how the state of what's in v1.20 compares to un-spec'ed dialyzer. I was under the impression that dyalizer's "success typing" approach (not flagging a function if there are some combination of parameter…

I know this is blasphemy to the average HN reader, but as a professional Elixir developer for 10 years, never have I felt the need for stronger compile-time type guarantees. None of my production services have had downtime or crashes because of type errors. Sure, at times, for very data-intensive sections of the application I would have loved something a bit more complex than dialyzer, but the guarantees offered by OTP and its actor model are much more important than compile-time type checking.

Of course people used to write server software in compiled languages feel the need for them because any runtime bug means downtime, but in BEAM land you'd have to work very, very hard to see your application crash in the classic sense, causing downtime and gnashing of teeth. And Elixir is strong typed enough never to cause the type of bugs you see in Javascript land, for example (i.e. a string is a string, not a number in some conditions)

That said, I'm perfectly happy for José and team to work on this niche feature, because for me, the language is pretty much done and all the improvements are on the OTP and library side rather than Elixir itself.

Re: Elixir v1.20: Now a gradually typed language

#289

Post by sph »

isityettime wrote: post #196
sph wrote: post #33

Earlier quoted context omitted.

I'm working on a game engine right now (written in object oriented language, of course) and I keep itching to design a compiled functional language for games, because state spread in thousand of objects, eldritch class hierarchies, are complete hell. Once you taste Elixir/Erlang, there is no going back to the madness.

> I keep itching to design a compiled functional language for games Jank wants to be this, right? IIRC its author and chief maintainer was a game dev before he dedicated himself to the language. https://jank-lang.org/ Maybe porting your engine would be a great way to prove out Jank 1.0 when it arrives ;)

Thanks for the pointer, never heard of this!
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