Rust isn’t strictly functional? Do you mean you’d like a language with garbage collection?
this post was submitted on 29 Aug 2024
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It's not a functional language at all, even if it borrows ideas from FP languages. It's an imperative language through and through.
"It's not a functional language at all even though it has lots of functional language features"
What? Rust is really quite a functional language in style, even if can easily support an imperative style too.
What exactly do you think makes something a functional language? Apart from currying I can't think of any typical FP features it is missing.
Fundamentally it's a language oriented around blocks of statements rather than composition of expressions. Additionally, it takes a different approach to the mutation problem than FP languages: where FP seeks to make most things pure and push mutation and side effects to the edges of the program, Rust uses its type system to make such mutation and side effects more sane. It's an entirely different philosophy when it comes to programming. I don't think either approach is necessarily better, mind you, just a different set of tradeoffs.
I'm a professional Haskell developer and am very much immersed in FP. When I read Rust code, I have to completely shift my thinking to something much more imperative. Whereas if I read, say, Ocaml, the difference is mostly syntactic. This isn't a slight, mind you. I quite like Rust. But it's a very different paradigm.
where FP seeks to make most things pure
I made this mistake for ages because Haskell is so popular and it's functional and pure, but it's not actually a requirement for functional languages to be pure. OCaml isn't.
When I read Rust code, I have to completely shift my thinking to something much more imperative.
I agree Rust code has a different feel to OCaml code but that's because it makes some things easier (e.g. mutation, vectors). You still could write Rust as if it was OCaml (except for the lack of currying), it's just that nobody does that because it sucks.
I think we're probably agreeing, it's just that "functional programming" is extremely poorly defined and we're interrupting it differently. You're thinking "a language where people write enormous nested expressions and over-use recursive functions and linked lists" and I'm thinking "a language that supports lots of features common in the FP paradigm: first class functions, pattern matching, expression based not statement based, iterators/map/filter/reduce, currying, tagged unions/sum types, etc."
I made this mistake for ages because Haskell is so popular and it's functional and pure, but it's not actually a requirement for functional languages to be pure. OCaml isn't.
I didn't say that FP languages have to necessarily be pure, just that FP languages tackle the problem of mutation by arranging programs such that most things are typically pure and side effects typically happen at the periphery (logging is probably the one exception, though). This is true even in FP languages that allow arbitrary side effects in functions, it's just not enforced by a compiler.
I agree Rust code has a different feel to OCaml code but that's because it makes some things easier (e.g. mutation, vectors). You still could write Rust as if it was OCaml (except for the lack of currying), it's just that nobody does that because it sucks.
That's the entire point, though. It's all about what the language emphasizes and makes easy to do. If it's unnatural to write a functional program in Rust and no one does it, then it's not really reasonable to call it a functional language. Writing functional programs is not idiomatic Rust, and that's okay.
I find Zig a language wuth very good WASM support out of the box and it is mostly imperative in nature.
It is currently pre 1.0 and has some rough edges.
You can use Go and compile with TinyGo.
The downside of that is that you have to code in Go
That is a downside, yes...
I wish the "standard" Go's WASM support was better.
Rust?
I haven't done too much work with WASM myself, but when I did, the only languages I saw recommended were Rust, C++, or TinyGo. From what I've heard, Rust and C++ are smoother than TinyGo. Garbage collected languages usually aren't great choices for compiling to wasm because wasm doesn't have any native garbage collection support. That limits your selection down a lot.
But another option you may want to consider is Nim. As I understand, it compiles to C, so any C->Wasm compiler should theoretically work for you as well. I did a quick search and wasn't able to find any great resources on how to do this, but you might get a bit more lucky. Good luck!
Swift could be a good choice.
When is Swift ever a good choice?... JK :)
Ive done C++ and C# before. Both work but it still feels very experimental in browser support. Ive put lisp in the browser through wasm with C++. Its was a fun novelty.
Scala-js is working on it - as its compiler design may facilitate this.
I haven't yet tried (on todo list) and am not an expert, but bookmarked in passing:
recent github implementation, some history, following older discussion
Scala-js is becoming my go to scala backend. I did not know there was a wasm feature coming. Will try
What are you building, it depends a bit on your usecase
Otherwise c# Blazor compiles to WASM
Late here, but if you want the easy route then there is always Unity (C#) if it fits for your use case in game dev and the license isn't a problem for you.