It looks like a tidy little functional language - a small, easily grasped syntax surface and generally clear semantics. That you've got it to the point that it can compile and run proper programs is a great achievement for a solo dev project!
The string type in the standard library isn't Unicode-aware, might be worth just noting that. Unicode support can be a big undertaking, but considering whether you'll add it later or not might affect your library design now.
I don't really understand why you have an IO monad. The language isn't pure - `.exec()` means any function can perform IO actions no matter its type signature - so what's IO really for?
Do `impl` additions export? What happens when two libraries add the same function name with different signatures (or just bodies!) to a type's `impl` ?
Is currying automatic? It doesn't seem to be, but, eg, the `sum(x: i32, y: i32)` function theoretically could be called as `sum(5)` to create a closure, but this isn't a documented feature if so.
The website's font is using ligatures, not unicode operator symbols - I'd personally find it much clearer to use a non-ligature font to show what's really there, but that's immaterial to the language.
First of all thanks for all the feedback and looking into it, appreciate it!
Yeah GRIN is a great project, it took a lot of debugging and analysis to make it compile 100% especially with monomorphization involved.
I'll look into Unicode support, makes total sense. Didn't scope it in initially. I can fix the site ligatures too, that's a fair remark.
> I don't really understand why you have an IO monad. The language isn't pure - `.exec()` means any function can perform IO actions no matter its type signature - so what's IO really for?
That's a fair point, I still left a place for `.exec()` to happen as un-handled side-effect. But the preference is with using the IO monad as the stdlib is built around it, with `main() -> IO[i32]` as a type signature. As languages evolves I'm planning to build a runtime around IO execution, and build more constraints for handling strict side-effects. However for this initial stage of the language, I left it as a really simple solution.
> Do `impl` additions export? What happens when two libraries add the same function name with different signatures (or just bodies!) to a type's `impl` ?
For now the language doesn't support modules (libraries), I'm planning on adding it. At the moment it's a bit of undefined behavior, as overloading would occur with latest `impl` definition.
> Is currying automatic? It doesn't seem to be, but, eg, the `sum(x: i32, y: i32)` function theoretically could be called as `sum(5)` to create a closure, but this isn't a documented feature if so.
In the type-system it is automatic, and it successfully passes type checker as it's entirely built on top of lambda calculus. But there's an issue with codegen right now. I can def look into it and document it.
trait Functor[A]:
fun map[B](self, f: A -> B) -> Self[B];
This looks a little wacky to me. I see that you can write HKTs in their η-long form and refer to them unapplied (`Functor`). But I don't understand how I would use this syntax to attach something to the trait that _doesn't_ depend on `A`. For (a silly) example,
trait SizedFunctor[A]: Functor[A]:
type Size;
fun size(self) -> Size;
How do I know that `List[A]::Size` is the same type as `List[B]::Size`?
Relatedly, I want to read `Self` in there as ‘the thing that implements `Functor[A]`’ (e.g. List[A]`), but that makes `Self[B]`, instantiated, mean `List[A][B]`, which I think should be a kind error.
Haskell is a great language with a really advanced type-system, although I found its syntax hard to read at times especially as I was exploring the language at first. On the other hand I really liked how Rust syntax was defined in terms of ADTs, Traits & Methods Impls, with type signatures required for functions. Hence I wished for a similar functional language that has such write-style and type concepts, but stripping away the borrow checker, mutations, etc.
It looks like a tidy little functional language - a small, easily grasped syntax surface and generally clear semantics. That you've got it to the point that it can compile and run proper programs is a great achievement for a solo dev project!
The string type in the standard library isn't Unicode-aware, might be worth just noting that. Unicode support can be a big undertaking, but considering whether you'll add it later or not might affect your library design now.
I don't really understand why you have an IO monad. The language isn't pure - `.exec()` means any function can perform IO actions no matter its type signature - so what's IO really for?
Do `impl` additions export? What happens when two libraries add the same function name with different signatures (or just bodies!) to a type's `impl` ?
Is currying automatic? It doesn't seem to be, but, eg, the `sum(x: i32, y: i32)` function theoretically could be called as `sum(5)` to create a closure, but this isn't a documented feature if so.
The website's font is using ligatures, not unicode operator symbols - I'd personally find it much clearer to use a non-ligature font to show what's really there, but that's immaterial to the language.
Yeah GRIN is a great project, it took a lot of debugging and analysis to make it compile 100% especially with monomorphization involved.
I'll look into Unicode support, makes total sense. Didn't scope it in initially. I can fix the site ligatures too, that's a fair remark.
> I don't really understand why you have an IO monad. The language isn't pure - `.exec()` means any function can perform IO actions no matter its type signature - so what's IO really for?
That's a fair point, I still left a place for `.exec()` to happen as un-handled side-effect. But the preference is with using the IO monad as the stdlib is built around it, with `main() -> IO[i32]` as a type signature. As languages evolves I'm planning to build a runtime around IO execution, and build more constraints for handling strict side-effects. However for this initial stage of the language, I left it as a really simple solution.
> Do `impl` additions export? What happens when two libraries add the same function name with different signatures (or just bodies!) to a type's `impl` ?
For now the language doesn't support modules (libraries), I'm planning on adding it. At the moment it's a bit of undefined behavior, as overloading would occur with latest `impl` definition.
> Is currying automatic? It doesn't seem to be, but, eg, the `sum(x: i32, y: i32)` function theoretically could be called as `sum(5)` to create a closure, but this isn't a documented feature if so.
In the type-system it is automatic, and it successfully passes type checker as it's entirely built on top of lambda calculus. But there's an issue with codegen right now. I can def look into it and document it.
Relatedly, I want to read `Self` in there as ‘the thing that implements `Functor[A]`’ (e.g. List[A]`), but that makes `Self[B]`, instantiated, mean `List[A][B]`, which I think should be a kind error.