Monad

ELI5 — The Vibe Check

A monad is a design pattern for chaining operations that have extra 'context' — like maybe-empty values, async results, or errors. Everyone who understands monads is contractually obligated to write a terrible tutorial about them. They're burritos. No wait, they're boxes. No, they're just flatMap.

Real Talk

A mathematical structure from category theory used in functional programming to sequence computations that involve context (optionality, errors, async, state). A monad is a type M with two operations: 'return' (wrapping a value) and 'bind/flatMap' (chaining operations). Promises, Option, Result, and arrays are all monads.

Show Me The Code

// Promise is a monad! .then() is bind/flatMap
fetch('/api/user')
  .then(res => res.json())      // flatMap
  .then(user => fetch(user.url)) // flatMap
  .then(res => res.json());      // flatMap

When You'll Hear This

"Once you realize Promise.then is just monadic bind, everything clicks." / "You don't need to understand category theory to use monads — you already use them every day with Promises and arrays."