purescript VS Idris2

When I see this it makes me want to run for ReasonML/ReScript/Elm/PureScript.

Sum types (without payloads on the instances they are effectively enums) should not require a evening filling ceremonial dance event to define.

https://reasonml.github.io/

https://rescript-lang.org/

https://elm-lang.org/

https://www.purescript.org/

(any I forgot?)

It's nice that TS is a strict super set of JS... But that's about the only reason TS is nice. Apart from that the "being a strict super set" hampers TS is a million and one ways.

To my JS is too broken to fix with a strict super set.

A web application makes use of these same ingredients, i.e. HTML, CSS, and JavaScript, but it uses significantly more JavaScript. As the JavaScript powering your web application grows in size it can bring with it a variety of problems that a few languages, like TypeScript, ReScript, PureScript, and Elm, have attempted to solve. Each of the aforementioned compile to JavaScript languages have their pros and cons but it is beyond the scope of this article to get into those details. Suffice it to say, my preference is Elm. It is also not the goal of this article to convince you to use Elm but only to show you how Elm fits into the flow of creating a web application and hosting it on GitHub Pages. So let's continue by adding Elm to our project.

Naturally I’d recommend using a better language such as ReScript or Elm or PureScript or F#‘s Fable + Elmish, but “React” is the king right now and people perceive TypeScript as “less risky” for jobs/hiring, so here we are.

Unless you want to switch to https://www.purescript.org/.

PureScript[1][2] seems pretty alive these days. From my relatively small, self-contained experiments, it's a lot more flexible and expressive than Elm at the expense of (maybe?) being a bit harder to learn up-front.

[1]: https://www.purescript.org/

[2]:https://github.com/purescript/purescript

Idris[1] and most of the dependent typed languages that I've looked at use de Bruijn numbers. (As does my own[2].)

The Idris implementation also has a list of names in scope as an argument to the type of a Term, which makes the compiler (also Idris) check if you're making a mistake with your de Bruijn indices. (I did not do this in mine, but I should have.)

[1]: https://github.com/idris-lang/Idris2

Have you looked into Idris2 at all. While looking into these theorum provers, it always felt like they had an impedance mismatch with normal programming.

Idris2 portends to a general purpose language that also has a more advanced type system for the theorum proving.

https://github.com/idris-lang/Idris2

The original paper also does plain STLC first in section 2, and then adds dependent types in section 3. (And finally it adds the naturals in section 4.)

In the Idris2 github repository, Guillaume Allais goes a step further and shows a well-named version. There the types of terms and values are indexed by the list of names in the environment and the compiler checks that the manipulation of deBruin levels and indices is correct:

https://github.com/idris-lang/Idris2/blob/main/libs/papers/L...

Most of the proof assistants out there: Lean, Coq, Dafny, Isabelle, F*, Idris 2, and Agda. And the main concepts are dependent types, Homotopy Type Theory AKA HoTT, and Category Theory. Warning: HoTT and Category Theory are really dense, you're going to really need to research them.

Idris2 has a great syntax for this, see e.g. node018:

I asked because it just baffles me any time I see a dependently typed language using unary numbers. I think to myself, "are these people even educated? Do they know about number systems?" I mean, cavemen were the last group using unary number system as their mainstay, and that was during the Paleolithic. Then they have issues open like this when they discuss optimizing those damn unaries. But this shouldn't even have been a problem for anyone even remotely related to programming! It's giving a terrible impression of dependently-typed languages. Getting rid of those should be the first step of popularizing them.

addOne : Int -> EitherT String IO Int addOne x = pure $ x + 1 add : Int -> Int -> EitherT String IO Int add x y = pure $ x + y main : IO () main = do exportFn `{add} the (IO ()) $ exportFn `{addOne} -- `the (IO ())` is needed due to issue https://github.com/idris-lang/Idris2/issues/2851