Gagnrunnsfræði

Gagnrunnsfræði, often translated as functional programming, is a programming paradigm that treats computation as the evaluation of mathematical functions and avoids changing-state and mutable data. It is a declarative programming style, meaning it focuses on what the program should accomplish rather than how to accomplish it.

Key concepts in Gagnrunnsfræði include pure functions, immutability, first-class functions, and recursion. A pure function always produces the same output for the same input and has no side effects, meaning it does not alter any state outside of its scope. Immutability means that once data is created, it cannot be changed. First-class functions are treated as first-class citizens, meaning they can be passed as arguments, returned from other functions, and assigned to variables. Recursion is a technique where a function calls itself to solve smaller instances of the same problem, often replacing traditional loops.

Gagnrunnsfræði emphasizes composing small, reusable functions to build complex programs. This approach can lead to code that is easier to understand, test, and debug, as well as more robust and parallelizable. Many modern programming languages support or are inspired by functional programming principles, even if they are not purely functional languages. Examples include Haskell, Scala, Clojure, and features within languages like JavaScript, Python, and Java. The adoption of functional concepts aims to improve software quality by managing complexity and reducing common sources of errors.