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Programming Paradigms

Programming paradigms refer to the fundamental styles or approaches to programming. They dictate how we structure and organize our code to solve problems.

Imperative Programming​

Imperative programming focuses on describing how to achieve a task step-by-step. It emphasizes changing program state through statements that modify mutable variables and data structure.

  • Uses statements like assignments, loops, and control structures (if-else, switch).

  • Directly specifies the sequence of operations and their effects on state.

  • Often closely tied to the underlying machine architecture and execution model.

Examples include languages like C, Python (to some extent), and Java.

Example: Computing Factorial Imperatively​

function factorial(n) {
  let result = 1;
  for (let i = 1; i <= n; i++) {
    result *= i;
  }
  return result;
}

console.log(factorial(5)); // Output: 120

Declarative Programming​

Declarative programming focuses on describing what you want to achieve without explicitly detailing how to achieve it. It emphasizes expressing the logic of a computation without describing its control flow.

  • Often uses expressions and declarations rather than statements.

  • Avoids explicit control flow and mutable state.

  • Often more abstract and high-level.

Examples include functional programming languages (like Haskell, Lisp) and SQL (for database queries).

Example: Computing Factorial Using Recursion

function factorial(n) {
  if (n <= 1) {
    return 1;
  }

  return n * factorial(n - 1);
}

console.log(factorial(5)); // Output: 120