## Monad in programming and category theory

This article is very much my attempt to understand monad as a design pattern in programming languages and why on earth it is useful. There are tons of monad tutorials online, but I found relatively few ones argue for the usefulness of a monad by having side by side code examples that achieve similar functionalties. If you found one, please do let me know! I try to draw connections between monads’ original mathematical definition and its actual usage so that this mysterious concept does not come out of the blue....