What are first-class functions and how do they differ across programming languages?

What are first-class functions and how do they differ across programming languages?

First-class functions are functions that can be treated like any other variable. This means they can be assigned to variables, passed as arguments, or returned from other functions. Different programming languages implement first-class functions in various ways.

Can you give examples of languages that support first-class functions?

Sure! Languages like JavaScript, Python, and Ruby all support first-class functions. In JavaScript, for instance, functions can be assigned to variables and passed around just like any other object.

How do first-class functions in JavaScript compare to those in Python?

In JavaScript, functions are first-class citizens and can be used as callbacks, while Python also treats functions as first-class but emphasizes readability and simplicity in function definitions.

Are there any languages that do not support first-class functions?

Yes, some languages like Java (prior to Java 8) do not support first-class functions in the same way. However, with the introduction of lambda expressions in Java 8, it has become more functionally oriented.