Chapter 8: Functions in Rust

Functions lie at the heart of any programming language. They enable you to organize code into self-contained units that can be called repeatedly, helping your programs become more modular and maintainable. In Rust, functions are first-class citizens, meaning you can store them in variables, pass them around as parameters, and return them like any other value.

Rust also supports anonymous functions (closures) that can capture variables from their enclosing scope. These are discussed in detail in Chapter 12.

This chapter explores how to define, call, and use functions in Rust. Topics include:

  • The main function
  • Basic function definition and calling
  • Parameters and return types
  • The return keyword and implicit returns
  • Function scope and nested functions
  • Default parameters and named arguments (and how Rust handles them)
  • Slices and tuples as parameters and return types
  • Generics in functions
  • Function pointers and higher-order functions
  • Recursion and tail call optimization
  • Inlining functions
  • Method syntax and associated functions
  • Function overloading (or the lack thereof)
  • Type inference for function return types
  • Variadic functions and macros