Statements And Expressions

The widget function in the last example looked like this:

fn widget() -> i32 {
  5 + 5
}

I bring this up to point out that there is no ; after the 5 + 5. This is different than all the other lines we've seen in functions so far. For example:

println!("Hello, World");

The reason for this difference is because Rust functions are made up of two types of things: Statements and Expressions.

From The Rust Book:

• Statements are instructions that perform some action and do not return a value.
• Expressions evaluate to a resultant value.

Said another way, expressions give you something back. Statements don't.