What is functional programming?

• Functional programming is a programming paradigm in which everything is bound using pure mathematical functions. It's a declarative programming approach. In contrast to an imperative style, which focuses on 'how to solve,' it focuses on 'what to solve.' Instead of statements, it use expressions. A statement is executed to assign variables, but an expression is evaluated to create a value.
• Functional programming is a programming paradigm in computer science in which programmes are built by applying and composing functions.
• It's a declarative programming paradigm in which function declarations are trees of expressions that map values to other values instead of a series of imperative statements that update the program's running state.

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