C# Feature – Lambda expressions

Overview

Lambdas are anonymous functions with expression or block bodies, foundational to LINQ and functional patterns.

Introduced In

C# 3 (2007)

Before

List<int> Filter(List<int> xs, Predicate<int> pred) { /* ... */ }

After

var evens = numbers.Where(n => n % 2 == 0).ToList();

Annotated Example

Func<int,int> square = x => x * x; // expression-bodied
Console.WriteLine(square(5));

Gotchas & Best Practices

• Capture semantics: avoid capturing loop variables incorrectly.

Related Features

• Extension methods
• LINQ query expressions

Version Notes

• Default lambda parameters in C# 12.