Rust: Write Arc<Mutex<Box<dyn FnMut(&'a T) + 'a>>> to keep the borrow checker happy.
Also Rust: fn x()->[i32;9] { std::array::from_fn(|i| 1) }
Dev: Wait, where did i come from?! Rust: I looked at your return type, did the math, checked your search history, and inferred it. 🦀🪄
8 days ago