liberal-accept-strict-return

What problem does it solve?

This pattern helps API designers and library authors balance flexibility with clarity by allowing broader input types while returning a fixed, precise output format. It applies Postel's Law to TypeScript and similar systems to improve usability without sacrificing downstream correctness.

Core Features & Use Cases

• Accept multiple input formats or optional fields to make APIs easier to use.
• Return a single, well-defined structure with concrete types to simplify consumption.
• Use Case: Designing a function signature or API where callers may provide varied inputs but should receive a predictable result.

Quick Start

Broaden input types and constrain output to a single, precise format in your API design.