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> I’m not the GP, but already Elixir can already accomplish compile time text processing with metaprogramming (like it does for inline html templating for ‘heex

> I’m not the GP, but already Elixir can already accomplish compile time text processing with metaprogramming (like it does for inline html templating for ‘heex’ functions and files) It's not the compile time text processing that's interesting, it's the fact that this compile time code can yield incredibly detailed types, and the fact that it's all done purely using type annotations. Almost every language that's used to build websites has some sort of server side templating language where you can sprinkle some code into your html templates. > That it hasn’t been done yet is probably because no one has deemed to worthwhile to implement. Maybe, or maybe it's less feasible without an advanced type system. The final version of the JSON example we're talking about ended up being 61 lines of code. Without some concrete Elixir code to inspect, this conversation is becoming very abstract. Honestly even if some of this were possible with metaprogramming, my intuition is that it would be much more verbose and complex. I feel like if I tried to implement all of the features of TypeScript by mucking around with an abstract syntax tree using metaprogramming, I would end up with a difficult to maintain crude approximation of the real thing. I don't think we're giving compiler developers enough credit by saying everything they've worked on can be replaced with a quick macro. José Valim's blog post on static typing ended with an announcement that they've sponsored a PhD student to work on these problems. After two days of discussion, I think we're reaching a bit of an impasse. Honestly just use what works for you!

h0l0cube 3y ago
> It's not the compile time text processing that's interesting You've talked right past me. Metaprogramming is not compile time text processing. > Honestly even if some of this were possible with metaprogramming, my intuition is that it would be much more verbose and complex. No. It's probably even how the Microsoft team are achieving the typing you're talking about. The special sauce here isn't as special as you think. > I think we're reaching a bit of an impasse Not really. I was just saying that what you're talking about is totally possible with metaprogramming. Not making some rhetorical play. > José Valim's blog post on static typing ended with an announcement that they've sponsored a PhD student to work on these problems. That's specifically because strict static typing with guards^ is at least difficult, but maybe impossible, and that's what the PhDs are trying to figure out. However, dialyzer isn't as hobbled as you imagine/purport it to be – the crux of my counterargument – and actual experience trumps speculation or casual reading on the topic. FYI, guards and pattern matching are one of the reasons why Elixir is so damn expressive, and this kind of function typing isn't available/possible in most non-functional languages ^ https://hexdocs.pm/elixir/guards.html https://hexdocs.pm/elixir/guards.html
- Vaguely2178 3y ago
  > You've talked right past me. Metaprogramming is not compile time text processing. I'm not talking past you. I never said metaprogramming is compile time text processing. You said "Elixir can already accomplish compile time text processing with metaprogramming", and I was just pointing out that the text processing itself is not the most interesting part of the example, it's the resultant types. > No. It's probably even how the Microsoft team are achieving the typing you're talking about. The special sauce here isn't as special as you think. But I don't have to reimplement any of this, because Microsoft has already written it. With enough time maybe you could implement dependent typing using metaprogramming for example, but would you then say that Elixir is just as good at dependent typing as Idris, which has that feature built in? > I was just saying that what you're talking about is totally possible with metaprogramming. You've graduated from saying "I think someone more savvy with Elixir would know more." to "totally possible"[1]. This does not sound like an argument from experience. > That's specifically because strict static typing with guards^ is at least difficult, but maybe impossible, and that's what the PhDs are trying to figure out. A lot of what you're talking about has already been implemented in other languages. This is not untrodden ground. There's no syntactic sugar for guards in JS (which TS just adds type annotations to), but semantically it's very similar to type narrowing in TS [2], which I use daily. This is not something I've read about casually on the internet. [1] https://news.ycombinator.com/item?id=35944988 https://news.ycombinator.com/item?id=35944988 [2]https://www.typescriptlang.org/docs/handbook/2/narrowing.html#handbook-content https://www.typescriptlang.org/docs/handbook/2/narrowing.htm...
  - h0l0cube 3y ago
    > This is not something I've read about casually on the internet Was speaking specifically about your opinions on Dialyzer and Elixir. It's very much a cursory Google around and having stronger opinions about the limits of a language than people who spend time with the language. > You've graduated from saying "I think someone more savvy with Elixir would know more." It took further reflection on the idea. It helps to start with at least some epistemic humility, once again the crux of this thread. I'm willing to revert to, "It ought to be possible" given that macros boil down to the final generated code (including typespecs) which is then analyzed by Dialyzer > Elixir is just as good at dependent typing as Idris, which has that feature built in? Metaprogramming allows features to become 'built in'. e.g., being able to integrate type checking and compiler errors for HTML/XML or other DSLs. https://hexdocs.pm/eex/EEx.html#function_from_string/5 https://hexdocs.pm/eex/EEx.html#function_from_string/5 https://hexdocs.pm/phoenix_live_view/0.17.0/Phoenix.LiveView.Helpers.html#sigil_H/2 https://hexdocs.pm/phoenix_live_view/0.17.0/Phoenix.LiveView...

h0l0cube 3y ago

> It's not the compile time text processing that's interesting You've talked right past me. Metaprogramming is not compile time text processing. > Honestly even if some of this were possible with metaprogramming, my intuition is that it would be much more verbose and complex. No. It's probably even how the Microsoft team are achieving the typing you're talking about. The special sauce here isn't as special as you think. > I think we're reaching a bit of an impasse Not really. I was just saying that what you're talking about is totally possible with metaprogramming. Not making some rhetorical play. > José Valim's blog post on static typing ended with an announcement that they've sponsored a PhD student to work on these problems. That's specifically because strict static typing with guards^ is at least difficult, but maybe impossible, and that's what the PhDs are trying to figure out. However, dialyzer isn't as hobbled as you imagine/purport it to be – the crux of my counterargument – and actual experience trumps speculation or casual reading on the topic. FYI, guards and pattern matching are one of the reasons why Elixir is so damn expressive, and this kind of function typing isn't available/possible in most non-functional languages ^ https://hexdocs.pm/elixir/guards.html https://hexdocs.pm/elixir/guards.html

Vaguely2178 3y ago
> You've talked right past me. Metaprogramming is not compile time text processing. I'm not talking past you. I never said metaprogramming is compile time text processing. You said "Elixir can already accomplish compile time text processing with metaprogramming", and I was just pointing out that the text processing itself is not the most interesting part of the example, it's the resultant types. > No. It's probably even how the Microsoft team are achieving the typing you're talking about. The special sauce here isn't as special as you think. But I don't have to reimplement any of this, because Microsoft has already written it. With enough time maybe you could implement dependent typing using metaprogramming for example, but would you then say that Elixir is just as good at dependent typing as Idris, which has that feature built in? > I was just saying that what you're talking about is totally possible with metaprogramming. You've graduated from saying "I think someone more savvy with Elixir would know more." to "totally possible"[1]. This does not sound like an argument from experience. > That's specifically because strict static typing with guards^ is at least difficult, but maybe impossible, and that's what the PhDs are trying to figure out. A lot of what you're talking about has already been implemented in other languages. This is not untrodden ground. There's no syntactic sugar for guards in JS (which TS just adds type annotations to), but semantically it's very similar to type narrowing in TS [2], which I use daily. This is not something I've read about casually on the internet. [1] https://news.ycombinator.com/item?id=35944988 https://news.ycombinator.com/item?id=35944988 [2]https://www.typescriptlang.org/docs/handbook/2/narrowing.html#handbook-content https://www.typescriptlang.org/docs/handbook/2/narrowing.htm...
- h0l0cube 3y ago
  > This is not something I've read about casually on the internet Was speaking specifically about your opinions on Dialyzer and Elixir. It's very much a cursory Google around and having stronger opinions about the limits of a language than people who spend time with the language. > You've graduated from saying "I think someone more savvy with Elixir would know more." It took further reflection on the idea. It helps to start with at least some epistemic humility, once again the crux of this thread. I'm willing to revert to, "It ought to be possible" given that macros boil down to the final generated code (including typespecs) which is then analyzed by Dialyzer > Elixir is just as good at dependent typing as Idris, which has that feature built in? Metaprogramming allows features to become 'built in'. e.g., being able to integrate type checking and compiler errors for HTML/XML or other DSLs. https://hexdocs.pm/eex/EEx.html#function_from_string/5 https://hexdocs.pm/eex/EEx.html#function_from_string/5 https://hexdocs.pm/phoenix_live_view/0.17.0/Phoenix.LiveView.Helpers.html#sigil_H/2 https://hexdocs.pm/phoenix_live_view/0.17.0/Phoenix.LiveView...