HashMap<_, Box<dyn Fn...>> - why does this feel wrong?

· Users Rust Lang · June 28, 2026, 11:22 a.m.
Summary
The author discusses the performance implications of using `Box<dyn Fn...>` in Rust, comparing it to Python's design philosophy that emphasizes ease of use for programmers over performance. They highlight that the appropriateness of this pattern in Rust largely depends on the intended use case, particularly whether it involves user interactions or high-volume calculations.