Functional Programming

What is functional programming?

a programming paradigm where code is written by applying and composing functions, avoiding side effects and mutable states

Advantages of functional programming

• requirements are better defined as functions than complex steps - fewer errors during implementation

• functions can be re-used within a program

• no side effects → easier to debug and test

• supports parallel/distributed processing (able to be used on big data)

Domain

All valid inputs for a function

Co-domain

The set of all possible outputs that a function could return

First-Class Objects

values that can be assigned to variables, passed as arguments, returned from functions and used in expressions

Higher-order functions

Functions that

• take a function as an argument

and/or

• return a function

Examples of higher-order functions

map, fold (reduce) and filter

Partial function application

Fixing one or more arguments of a function to produce a new function with fewer parameters

List Processing

splitting a list into the head (first index) and the tail (remaining elements)

Fold

Combines elements in a list into a singular value by repeatedly applying a function

Map

applies a function to each element in a list and returns a new list of results

filter

applies a function to each elements in a list, only keeping those that return True