Research what a functional programming language is and write down two examples.

A functional programming language is a type of programming language that treats computation as the evaluation of mathematical functions and avoids changing-state and mutable data. It emphasizes the application of functions, in contrast to the imperative programming style, which emphasizes changes in state.

Functional programming languages have their roots in lambda calculus and are widely used in academia and industry. They offer a number of advantages such as ease of debugging due to the absence of side effects, and they tend to be more concise and predictable than their imperative counterparts.

Here are two examples of functional programming languages:

1. Haskell: Haskell is a statically typed, purely functional programming language with type inference and lazy evaluation. It was designed to be a practical, yet high-level language for programming complex systems. It has a strong, static type system based on Hindley–Milner type inference.

2. Lisp: Lisp (LISt Processing) is one of the oldest high-level programming languages and the second-oldest high-level programming language in widespread use today. It was originally created as a practical mathematical notation for computer programs. Lisp pioneered many ideas in computer science, including tree data structures, automatic storage management, dynamic typing, and the self-hosting compiler.