> "One class per file".

Wait. What? Neither Java nor Rust limit class/struct per file. You must mean public class per file.

As a fellow Java dev, no it doesn't look like Java at all. Maybe it looks a bit like Kotlin, but only superficially.

I wrote Rust on and off for 5 years, by that time you internalize the borrow checker.

I did mean one public class per file.

I didn't mean syntax or core lib to be similar, I just generally meant that both languages impose restrictions on themselves which might seem sensible at first.

Java isn't that restrictive. Rust's type system is much more restrictive and customizable.

That said, a good way to think about programs is a series of restrictions, i.e. invariants. Truth be told, only Ada Spark so far really embraced invariants.