Prefer Imprecise Types to Inaccurate Types

Overview

An imprecise type that's correct is better than a precise type that's wrong.

When you make types more precise, you risk making them inaccurate. Inaccurate types cause false positives (valid code rejected) or false negatives (invalid code accepted). Both erode trust in the type system.

When to Use This Skill

• Making types "more precise"
• Getting unexpected type errors
• Types that reject valid use cases
• Debugging complex generic types

The Iron Rule