Converting F# to Rust: Discriminated Unions

Almost a year ago, I created an application in F# that was a file structure generator. I created it in F# to get a better feel for functional, and it was a pretty cool project. My friend Cameron helped me design some of the parts. I never really finished the vision that I had for that project and to finish it, I am going to convert it from F# to Rust. It’s a simple project, but it should prove to be useful for myself and any others working with Terraform.

The first thing I wanted to work on in this app is to figure out how to convert a Discriminated Union that leverages recursive types in F# to the correct type in Rust. This example may not be my final solution, but it is an exercise in converting some existing code. I think my naming may need some work, and I am open to suggestions.

Here is the type in F#:

type Folder = File of string | Folder of string * Folder list

The idea of this time is I can have a folder, and it can either have a file or a folder with a list of folders types. After reading through this blog post and relying on the fact that both languages have roots in OCaml, here is my Rust version.

enum Folder {
    File(String),
    Folder(String, Vec<Folder>)
}

It compiles, and I can use it almost the same fashion as I do in my F# code. I was surprised that it was so straight forward and reasonably intuitive to convert. I plan to do more posts as I convert this app over.

Thanks for reading,

Jamie

If you enjoy the content, then consider buying me a coffee.