match using "case Point2d(x,y):"

Rust takes this a step further:

Rust's match statements and function parameter syntax are (intentionally) quite tightly aligned - they are both "patterns".

The difference is that function parameter bindings must be irrefutable (always match), while match statement arms don't have to always match.

https://doc.rust-lang.org/reference/expressions/match-exp...
> A match expression branches on a pattern. The exact form of matching that occurs depends on the pattern.

https://doc.rust-lang.org/reference/items/functions.html#...
> As with let bindings, function parameters are irrefutable patterns, so any pattern that is valid in a let binding is also valid as an argument.

https://doc.rust-lang.org/reference/patterns.html#refutab...
> A pattern is said to be refutable when it has the possibility of not being matched by the value it is being matched against. Irrefutable patterns, on the other hand, always match the value they are being matched against.