# A Lean Syntax Primer

DevFeed: [A Lean Syntax Primer](<https://devfeed.tech/articles/a-lean-syntax-primer-36158.md>)

Original publisher: [Read original article](<https://overreacted.io/a-lean-syntax-primer/>)

Published: 2025-09-02T00:00:00Z

Content type: tutorial

Language: en

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

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

Tags: [code](<https://devfeed.tech/tags/code.md>), [how-to](<https://devfeed.tech/tags/how-to.md>), [learn](<https://devfeed.tech/tags/learn.md>), [programming](<https://devfeed.tech/tags/programming.md>), [syntax](<https://devfeed.tech/tags/syntax.md>), [types](<https://devfeed.tech/tags/types.md>)

## AI overview

An opinionated introduction to Lean syntax covering definitions, assignment and comparison syntax, type inference, explicit type annotations, natural numbers, integers, and running code in the online playground or VS Code. It also introduces the distinction between executing Lean code and proving facts about it.

## Source excerpt

Programming with proofs.