Programming a Guessing Game

General

By default, Rust has a set of items defined in the standard library that it brings into the scope of every program. This set is called the prelude.

If a type we want to use is not in the prelude, we have to bring that type into scope explicitly with a use command

• variable is immutable by default
• To be able to make a variable mutable, we add mut keyword before the variable name
• String::new(), for example is a usage of associated function. new is an associated function of String type

Reference

• The & indicates that this argument is a reference, which gives you a way to let multiple parts of code access one piece of data without needing to copy that data into memory multiple times.
• Reference, like variable is also immutable by default

Enum

• Result is an enum. A type that can be in one of multiple possible states. Each possible state is called variant
  • Ok
  • Error

Crate

• Crate is a collection of Rust source code files
• Cargo's coordination of external crates is where Cargo really shines
• Use cargo add <crate name> to import an external crate as a dependency
• Cargo.lock file guarantees the dependency version is locked to the specified SemVer
• To understand how to use a crate, issuing the command cargo doc --open will generate documentations of all the defined dependencies of the current project

Shadowing

let mut guess: String = String::new();
let mut guess: u32 = guess.trim().parse().expect("...");

• This feature is often used when you want to convert a value from one type to another type