> Can you give an example or provide a citation to this? It would look something like this: trait MyOperation { fn run(&mut self, a: T, b: U, c: V

> Can you give an example or provide a citation to this? It would look something like this: trait MyOperation { fn run(&mut self, a: T, b: U, c: V) -> R; } impl<F> MyOperation for F where F: FnMut(T, U, V) -> R { fn run(&mut self, a: T, b: U, c: V) -> R { self(a, b, c) } } fn my_api<F: MyOperation>(f: F) { ... f.run(a, b, c) ... } struct MyFunctor { ... } impl MyOperation for MyFunctor { ... } my_api(MyFunctor { ... }); That is, when defining `my_api` and you would like to accept both lambdas and functors, instead of using a `Fn` trait bound directly, use a more specific trait which has a blanket impl for lambdas.