Functional features in Rust

Rust has been inspired by functional languages such as Haskell and OCaml. Unsurprisingly, Rust has rich support for functional programming both in the language and in the standard library. In this section, we will look at some of these.

Higher-order functions

We have seen previously how Rust functions define an isolated scope in which all local variables live. Thus, variables outside the scope can never leak into it unless they are explicitly passed as arguments. There can be cases where this is not the desired behavior; closures provide an anonymous function like mechanism, which has access to all the resources defined in the scope in which it is defined. This enables the compiler to enforce the same borrow checking rules while making it easier to reuse code. In Rust terminology, a typical closure borrows all bindings of its surrounding scope. A closure can be forced to own those by marking it with the move keyword. Let's look at some examples:

// chapter2/closure...