What are impure functions and how do they affect programming?

What are impure functions and how do they affect programming?

Impure functions are functions that can produce side effects or depend on external state. Unlike pure functions, which always return the same output for the same input, impure functions can lead to unpredictable behavior.

Can you give me an example of an impure function?

Sure! An example of an impure function is one that modifies a global variable or interacts with a database. For instance, a function that increments a global counter each time it's called is impure.

Why should I avoid using impure functions?

Avoiding impure functions is important because they can make your code harder to test, debug, and maintain. They introduce unpredictability and can lead to bugs that are difficult to trace.

Are there any situations where impure functions are necessary?

Yes, sometimes impure functions are necessary, especially when dealing with I/O operations, like reading from a file or making network requests. In these cases, the side effects are often unavoidable.