Not very familiar with the libraries, and BB_C has already given a lot of more detailed feedback, but here are some small things:

• Even without rewriting get_files_in_dir as a single chain of method calls, you can still replace

  if dir.is_err() {  
      return None  
  };
  // use dir.unwrap()
  

  with

  let Ok(dir) = dir else {
      return None;
  };
  // use dir
  

  In general, if you can use if let or let else to pattern match, prefer that over unwrapping – Clippy has a lint relating to this, actually.
• Although the formatting doesn’t seem horrible, it doesn’t seem like Rustfmt was used on it. You might want to make use of it for slightly more consistent formatting. I mainly noticed the lack of trailing commas, and the lack of semicolons after return None in get_files_in_dir.

There was a recent langdev Stack Exchange question about this very topic. It’s a bit trickier to design than it might seem at first.

Suppose we require a keyword – say var – before all binding patterns. This results in having to write things like
for (&(var x1, var y1, var z1), &(var x2, var y2, var z2)) in points.iter().tuple_windows() {},
which is quite a bit more verbose than the current
for (&(x1, y1, z1), &(x2, y2, z2)) in points.iter().tuple_windows() {}.
Not to mention you’ll have to write let var x = 0; just to declare a variable, unless you redesign the language to allow you to just write var x = 0 (and if you do that, you’ll also have to somehow support a coherent way to express if let Some(x) = arr.pop() {} and let Some(x) = arr.pop() else {todo!()}).

Suppose we require a keyword – say const – before all value-matching patterns that look like variables. Then, what’s currently

match (left.next(), right.next()) {
    (Some(l), Some(r)) => {}
    (Some(l), None) => {}
    (None, Some(r)) => {}
    (None, None) => {}
}

turns into either the inconsistently ugly

match (left.next(), right.next()) {
    (Some(l), Some(r)) => {}
    (Some(l), const None) => {}
    (const None, Some(r)) => {}
    (const None, const None) => {}
}

or the even more verbose

match (left.next(), right.next()) {
    (const Some(l), const Some(r)) => {}
    (const Some(l), const None) => {}
    (const None, const Some(r)) => {}
    (const None, const None) => {}
}

and you always run the risk of forgetting a const and accidentally binding a new match-all variable named None – the main footgun that syntactically distinguishing binding and value-matching patterns was meant to avoid in the first place.

Suppose we require a sigil such as $ before one type of pattern. Probably the best solution in my opinion, but that’s one symbol that can no longer be used for other things in a pattern context. Also, if you’re already using sigils before variable names for other purposes (I’ve been sketching out a language where a pointer variable $x can be auto-dereferenced by writing x), doubling up is really unpleasant.

…So I can understand why Rust chose to give the same, most concise possible syntax for both binding and value-matching patterns. At least compiler warnings (unused, non-snake-case variables) are there to provide some protection from accidentally turning one into the other.

I would certainly rather see this than {isAdmin: bool; isLoggedIn: bool}. With boolean | null, at least illegal states are unrepresentable… even if the legal states are represented in an… interesting way.

Even regular Rust code is more “exciting” than Python in this regard, since you have a choice between self, &self, and &mut self. And occasionally mut self, &'a self, and even self: Box<Self>. All of which offer different semantics depending on what exactly you’re trying to do.

You can get the exclusive behaviour with random.randrange. (Relevant Stack Overflow question with a somewhat interesting answer)

Can’t resist pointing out how you should actually write the function in a “real” scenario (but still not handling errors properly), in case anyone wants to know.

If the list is guaranteed to have exactly two elements:

fn is_second_num_positive_exact(input: &str) -> bool {
    let (_, n) = input.split_once(',').unwrap();
    n.parse::<i32>().unwrap() > 0
}

If you want to test the last element:

fn is_last_num_positive(input: &str) -> bool {
    let n = input.split(',').next_back().unwrap();
    n.parse::<i32>().unwrap() > 0
}

If you want to test the 2nd (1-indexed) element:

fn is_second_num_positive(input: &str) -> bool {
    let n = input.split(',').nth(1).unwrap();
    n.parse::<i32>().unwrap() > 0
}

I can imagine Berdly Deltarune trying to explain this to Kris and Noelle in roughly this tone of voice.