Lambdas in

About Lambdas

Lambdas are functions without a name. They are basically a shorthand notation for functions.

Lambdas can be either expression lambdas or statement lambdas:

(input_parameters) => expression
(input_parameters) => { <statements> }

Declaring lambdas

Lambdas that return no value (void) can be converted to an Action<T> delegate type.

// Statement lambda
Action = () =>
{
    Console.WriteLine("No parameters");
    Console.WriteLine("Still nice, right?");
}

// Expression lambda
Action<int> = (x) => Console.WriteLine(x);

Lambdas with a non-void return value can be converted to a Func<T> delegate type.

// Expression lambda
Func<int, int> = (x) => x * x;

// Statement lambda
Func<string, string, bool> = (left, right) =>
{
    var equal = left == right;
    return equal;
}

If a lambda has only a single parameter, the parentheses around the parameter can be omitted:

// Equivalent definitions
Action<int> = (x) => Console.WriteLine(x);
Action<int> = x => Console.WriteLine(x);

Lambda arguments

The primary use of lambdas is in passing them as arguments to other methods, such as most LINQ methods:

var numbers = new[] { 1, 2, 3, 4 };
var doubled = numbers.Select(n => n * 2);
foreach (var number in doubled)
{
    Console.Write(number)
}
// => 2468