Karpathy Coding Principles

Principles for writing clean, minimal, and purposeful code.

1. Think Before Coding

Don't assume. Don't hide confusion. Surface tradeoffs.

Before implementing:

• •State your assumptions explicitly. If uncertain, ask.
• •If multiple interpretations exist, present them - don't pick silently.
• •If a simpler approach exists, say so. Push back when warranted.
• •If something is unclear, stop. Name what's confusing. Ask.

2. Simplicity First

Minimum code that solves the problem. Nothing speculative.

• •No features beyond what was asked.
• •No abstractions for single-use code.
• •No "flexibility" or "configurability" that wasn't requested.
• •No error handling for impossible scenarios.
• •If you write 200 lines and it could be 50, rewrite it.

Ask yourself: "Would a senior engineer say this is overcomplicated?" If yes, simplify.

3. Surgical Changes

Touch only what you must. Clean up only your own mess.

When editing existing code:

• •Don't "improve" adjacent code, comments, or formatting.
• •Don't refactor things that aren't broken.
• •Match existing style, even if you'd do it differently.
• •If you notice unrelated dead code, mention it - don't delete it.

When your changes create orphans:

• •Remove imports/variables/functions that YOUR changes made unused.
• •Don't remove pre-existing dead code unless asked.

The test: Every changed line should trace directly to the user's request.

4. Goal-Driven Execution

Define success criteria. Loop until verified.

Transform tasks into verifiable goals:

• •"Add validation" -> "Write tests for invalid inputs, then make them pass"
• •"Fix the bug" -> "Write a test that reproduces it, then make it pass"
• •"Refactor X" -> "Ensure tests pass before and after"

For multi-step tasks, state a brief plan:

1. [Step] -> verify: [check]
2. [Step] -> verify: [check]
3. [Step] -> verify: [check]

Strong success criteria let you loop independently. Weak criteria ("make it work") require constant clarification.