### What is a Lambda Expression?
A lambda expression is a concise way to represent an anonymous function — a function that is defined without a name. Lambda expressions are often used when you need a simple function for a short period of time or when you want to pass a function as an argument to another function.
### Syntax:
In many programming languages, the syntax for a lambda expression follows a general pattern:
“`
lambda parameters: expression
“`
Here, `lambda` is a keyword indicating the creation of a lambda expression. `parameters` are the inputs to the function, and `expression` is the computation performed by the function.
### Example:
Let’s say we have a list of numbers and we want to square each number in the list. We can achieve this using a lambda expression along with functions like `map()` or `filter()`:
“`python
numbers = [1, 2, 3, 4, 5]
squared_numbers = list(map(lambda x: x**2, numbers))
print(squared_numbers) # Output: [1, 4, 9, 16, 25]
“`
In this example, `lambda x: x**2` is a lambda expression that takes a single parameter `x` and returns `x**2`, effectively squaring the input.
### Key Points:
– **Anonymous Function:** Lambda expressions allow you to create functions without a formal name.
– **Short and Concise:** Lambdas are typically used for short, simple operations.
– **Functional Programming:** Lambdas are often used in conjunction with higher-order functions like `map()`, `filter()`, and `reduce()`.
### Use Cases:
– **Filtering:** Filtering elements from a collection based on a condition.
– **Transformation:** Transforming elements of a collection.
– **Sorting:** Providing custom sorting criteria.
– **Event Handling:** Defining event handlers in GUI programming.
– **As Arguments:** Passing a function as an argument to another function.
### Languages supporting Lambda Expressions:
– **Python**
– **JavaScript**
– **Java (starting from Java 8)**
– **C#**
– **Ruby**
– **Swift**
– **Scala**
– **Haskell**
– **Clojure**
– **and many more…**
Lambda expressions are a powerful tool in the programmer’s toolkit, enabling concise and expressive code in various programming paradigms.
