Show HN: Fuse – statically typed functional programming language

Show HN: Fuse – statically typed functional programming language(fuselang.org)

29 points by the_unproven 2 hours ago | 4 comments

Hi HN! I've been working on the fuse programming language, it's a statically typed purely functional language with higher-kinder types and ad-hoc polymorphism. It compiles to the GRIN whole-program optimizer, producing LLVM-generated native code.

Fuse supports ADTs, Generics, Type Methods, Traits, Pattern matching etc. all in a functional style with no mutations.

I’ve been developing the language for 5 years, with code written in Scala. I’ve started coding the language from the base of System F that was implemented as part of the book: Types and Programming Languages (tapl). And then extending with concepts such as Bidirectional Type Checking with Higher-Rank Polymorphism.

I’ve mainly drawn inspiration from Rust, Haskell, Scala and Python (in terms of syntax). It all started because I wanted a language that has Rust-like concepts such as: ADT, Traits, Impl block syntax, etc. but have the pure functional semantics.

I'd would love feedback on the language design and its general usage.

faangguyindia 2 minutes ago |

i loved haskell but cross platform haskell deployment is still pain

codebje 47 minutes ago |

It's nice to see a GRIN backend in the wild!

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.

the_unproven 6 minutes ago | |

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.

qsera 39 minutes ago |

I wish you took Haskell's syntax as such. Why did you mix rust and possibly other stuff with it?