hisham_hm

"Transpiler" is a common term for source-to-source compilers in the industry, but compiler is the more general term (i.e. a transpiler is a kind of compiler). In academia, the term "transpiler" is somewhat sneered at. A source-to-source compiler is still a compiler, because conceptually compiling into assembly is also technically source-to-source.

Hi, Teal creator here!

> How confident are you in the soundness of the type system?

I am confident it is not sound! That is by design. A typical example is how function arguments are bivariant, to allow for callbacks expressed the way programmers usually expect them to work (TypeScript does something similar).

> Also, are there any Lua constructs that are difficult/impossible to type?

Yes, many of them. The type system and the compiler are pragmatically very simple -- there are many design decisions made to favor simplicity of specification and/or implementation. (Compare the single-file, single-pass Teal compiler done mostly by a single person with the amount of engineering resources that Microsoft has put into TypeScript.) For a concrete example, we have special-cased polymorphism for functions, intended to use with very dynamically-typed Lua functions from the broader Lua ecosystem, but you cannot express similar polymorphism in Teal itself.

> Is type checking decidable? (Is the type system Turing complete?)

There is a proof (which I can't find right now) that type checking is not decidable once you combine parametric polymorphism (generics) and intersection types (like the poly functions I mentioned above), but the forms of these features supported by Teal have some restrictions which make me not extend such claims directly. And of course, I can't even claim that the implementation of the theoretical model is bug-free. The model is evolving, the implementation always lags a bit behind.

In any case, the goal for Teal's type system is not academic purity, but pragmatic utility. Other comments in this thread alluded to this as well -- there are practical constraints that come from targeting an existing language and ecosystem. Of course, there are many ways one can approach such challanges. Teal is one of them and there were and are certainly others! Everyone is free to take their shot at where they want to be in the Unix-Philosophy/Worse-is-Better vs. Lisp-Philosophy/The-Right-Thing design gradient.

it's a three element tuple.

In our experience, single-element tuples are just never used in practice. There has been some discussion on how to add syntax for them, but I think it's more of a desire for orthogonality than for a practical need.

Please try again, shouldn't be happening, hopefully!

Teal's output is currently pretty much 1-to-1 with the input apart from removing all of the type information of course. (I've been trying hard to keep it that way so that the error messages in stack traces match the input lines without having to do source mapping.)

Teal currenly supports generating code for Lua 5.1 and up, including LuaJIT. There are compiler flags --gen-target and --gen-compat which control various specifics of code generation.

There is also the compat53 library which polyfills most of the missing parts. The Teal compiler has --gen-target and --gen-compat flags which adapts the generated Lua code for different Lua versions, and allows using the compat53 library behind the scenes if desired, so you can get a mostly Lua-5.3+ experience over LuaJIT using Teal.

I wonder if it would be possible to make a usable dedicated hardware encryption card for the Apple II using 80s tech.

(Of course, it has the downside that upgrading to a new protocol would require a new card, but hey... we're just having fun musing on retro-futurism here!)

Interesting work! I admit I just skimmed the post quickly, so sorry if it's been mentioned already, but: is there a way for users to report/flag bad suggestions? On YouTube, for example, there's a similar list of "bubbles" for topics and I keep getting suggestions of topics I'm not interested in because I care for adjacent topics (e.g. for one soccer team because I follow another one). I'd love to be able to long-press the bubble and then get a report/flag option in a pop-up menu, for instance.

Nothing in the list above seems to be a feature adding or changing end-user-visible behavior, they are performance optimizations. They make cp/mv work the same way but faster.

Nothing new here unfortunately: this is pretty much how every story of open source development targeting proprietary platforms end, especially web-based platforms such as *aaS or social media. I remember the same thing happening with Twitter 9 years ago.

I can't help being pedantic and reiterating that smartphones with apps and stores existed before the iPhone. Let's not rewrite history. The iPhone's historical importance is overstated, especially when one considers the global market, where it was never a leading player. The US is very particular in that regard.

what does APT mean in this context? thank you!