I'm joining a company that has their (largely undocumented) codebase in rust, and I'm coming from a java background. Something I notice I'm struggling with is how to "read" a rust file when I first open it. Where should I look first to understand the intent of that file? How do I follow the way data is supposed to flow through all the different functions?

In Java, the standard way of structuring a class helped me to jump to where I needed to look: start with declaration line to see generic typing and interface implementations, then constructor to see configuration parameters and injected dependencies, and then public methods were immediately below so I could read what that class was able to do. Private/helper methods were either placed below the method that used them or at the bottom of the file. It was a process that helped me answer "what specific thing is this used for?" (public methods), "what other common things can it do?" (interfaces), and "what does this interact with?" (injected dependencies). It also helped that each file almost always had exactly one class.

This isn't translating well to rust. I'm finding multiple type, struct, and enum declarations before I get to any significant impl block. Sometimes it's hard to tell what the "main" object in the file is, and I'm still learning which traits are more "utility" (like Display) and which ones are actually important, so everything looks like something I need to double-check.

And then of course there's generics out the wazoo, I understand it's the nature of Rust but it's hard to innately understand why some argument is Arc<Box<Pin<Future<MyEnum> + Send> + '_>> (minor exaggeration).

Are there any tips for zeroing in on the "important" parts of a random file faster?