A small introduction to functional programming

Functional programming, an old paradigm rooted in Lambda Calculus developed by Alonzo Church, has gained renewed popularity for its concise, modular code and absence of side effects. Languages like Erlang, Haskell, and Scala are particularly suited to this style, although mainstream languages such as JavaScript, Python, and Java also incorporate functional concepts. Key features of functional programming include pure functions, where identical inputs yield identical outputs without side effects, first-class function treatment, and shorter code due to the absence of loops in favor of recursion. The text explores fundamental aspects such as immutable variables, pattern matching, anonymous functions, closures, and list comprehensions using examples in Haskell and Erlang, highlighting how these elements contribute to the unique characteristics of functional programming.