{
  "$type": "site.standard.document",
  "path": "/t/closures-and-functional-traits/23965#post_20",
  "publishedAt": "2026-02-05T07:23:52.000Z",
  "site": "https://internals.rust-lang.org",
  "textContent": "The `Fn*` family of traits does not express everything that can be expressed with a trait with one method. For example, you can define a trait with a generic method:\n\n\n    trait Foo {\n        fn foo<T>(&mut self, things: &mut [T]);\n    }\n\n\nIt’s impossible to express this as a usage of `FnMut` or to implement this using a `from_fn()`-style adapter.",
  "title": "Closures and functional traits"
}