The perfect functional programming language (for me)

I have been playing with functional languages a few times now. I have tried Haskell, Elm and Elixir so far, but also played a bit with a LISP-like language that is implemented in Rust for being easily embeddable into Rust programs.

Lately, I also played with “roc” (, which is a new approach for a functional programming language that can compile to binary (using LLVM) that also has some new ideas.

One of these ideas, that I quite like to be honest, is the idea of “platforms”. A developer has to write a minimal platform the program they want to write runs on. This platform is nothing more and nothing less than the interface between roc and the outside world – which is stateful! So the platform deals with allocation and deallocation, talks to the operating system to, for example, read from the commandline or handle incoming network traffic. The platform has to be very minimal, and must ensure that there is no state leaked through to the roc program!

roc itself has a syntax that is rather nice, although I think there can be improvements. The idea of the authors is that roc should be easy to use, like Elixir or Elm, spark joy in the programmer and still be fast. In fact, it has been shown (in a very unscientific benchmark IIRC, but that's more due to the fact that roc is in very early development as in due to other reasons) that roc can in fact outperform imperative languages in some cases! Leveraging the power of LLVM is one of the reasons for that, but also that roc enables performance optimizations that are not possible or very hard in other circumstances.

To conclude, I am really looking forward to roc and hope that it will be more “you can play with this”-ready than it is today. Right now, compiling everything from source all the time (roc is written in Rust) and having only very few pieces of documentation available, makes playing with roc hard. I hope that will improve soon.

To quote myself:

So my ideal #functional #language #programminglanguage would be a pure functional language with traits/interfaces, ergonomics like #ruby or #elm or #elixir, performance like #rust because it compiles to binary with #llvm, with the “platform” approach #roc #roclang currently has, so one can provide minimal interfaces to the OS ...

Which would make it a perfect language for #containers and #microservices but also #CLI tooling and even websites via #wasm (if it can compile to wasm)!

... and I think roc can be that language!

Please note that roc is not released as opensource codebase at the time of writing this article, but it will be as soon as the author thinks it is time. I wrote “roc” in lowercase letters in this article because – and only because – I think that's how it is intended.