Functional programming in Lisp

Functional programming in Lisp centers on constructing programs by combining pure functions—these are operations that consistently produce the same output for the same input without side effects. This approach emphasizes immutability and stateless computations, making code more predictable and easier to reason about. In Lisp, functions are treated as first-class citizens, meaning they can be assigned to variables, passed as arguments, or returned from other functions. This style promotes clear, modular, and concise code, enabling developers to build complex behaviors through simple, reusable functions, aligning closely with mathematical principles of function composition.