Rust gives each closure a unique type (see the `Fn` trait: https://doc.rust-lang.org/core/ops/trait.Fn.html https://doc.rust-lang.org/core/ops/trait.Fn.html), a

Rust gives each closure a unique type (see the `Fn` trait: https://doc.rust-lang.org/core/ops/trait.Fn.html https://doc.rust-lang.org/core/ops/trait.Fn.html), allowing the compiler to always statically dispatch to the exact function body at compile-time. That said, this is a rather more explicit approach that won't necessarily fit everything.