# A Taste of Lean: Formalizing Mathematics as Code

DevFeed: [A Taste of Lean: Formalizing Mathematics as Code](<https://devfeed.tech/articles/the-math-is-haunted-36199.md>)

Original publisher: [Read original article](<https://overreacted.io/the-math-is-haunted/>)

Published: 2025-07-30T00:00:00Z

Content type: tutorial

Language: en

Sources: [Dan Abramov](<https://devfeed.tech/sources/dan-abramov.md>)

Topics: [Lean](<https://devfeed.tech/topics/lean.md>), [math](<https://devfeed.tech/topics/math.md>), [Programming](<https://devfeed.tech/topics/programming.md>), [Code](<https://devfeed.tech/topics/code.md>)

Tags: [2025](<https://devfeed.tech/tags/2025.md>), [code](<https://devfeed.tech/tags/code.md>), [math](<https://devfeed.tech/tags/math.md>), [programming-language](<https://devfeed.tech/tags/programming-language.md>), [syntax](<https://devfeed.tech/tags/syntax.md>)

## AI overview

This tutorial introduces Lean, a programming language designed to formalize mathematics. It explains how Lean represents mathematical structures, theorems, and proofs as code, then uses a small equality theorem to demonstrate tactic states, incomplete proofs, universal proof suppression, and reflexivity.

## Source excerpt

A taste of Lean.