Optional arguments ^{C# 4.0} allows parameters to a method to assume a default in the absence of an explicit passed value.

C# 12.0 extends this to lambda expressions ^{C# 3.0}.

Code

Now

var shipOrder = (int x, int y = 1) => x + y;

Before

var increment = (int x, int y) => x + y;
var incrementBy1 = (int x) => increment(x, 1);

More information

• What's new in C# 12.0
• Language reference