简单的 lambda 表达式

// A simple adder function defined as a lambda expression. 
// Unlike with regular functions, parameter types often may be omitted because the
// compiler can infer their types
let adder = |a, b| a + b;
// Lambdas can span across multiple lines, like normal functions.
let multiplier = |a: i32, b: i32| {
    let c = b;
    let b = a;
    let a = c;
    a * b
};

// Since lambdas are anonymous functions, they can be called like other functions
println!("{}", adder(3, 5));
println!("{}", multiplier(3, 5));

这显示：

8
15