Monoids are the most basic way to combine any values. A monoid is algebra that is closed under an associative binary operation and has an identity element.
We can think of a monoid as a design pattern that allows us to quickly reduce (or fold) on a collection of a single type in a parallel way.
A monoid is anything that satisfies the following rules:
- Closure rule
- Associativity rule
- Identity rule
Let's discuss these rules in brief.
“If you combine two values of same type, you get another value of the same type.”
Given two inputs of the same type, a monoid returns one value of the same type as the input.