FP Algebra-Driven Design

Algebraic thinking for API design. Discover the right API before implementing by specifying rules (equations) that operations must satisfy.

Cross-references: fp-principles | fp-domain-modeling | fp-usable-design

1. Why Algebraic Thinking

[STARTER]

Code is the wrong abstraction level for design. Starting with data structures inherits unnecessary constraints.

• Specify rules first, implement second. Implementation is a solution to a system of equations.
• Rules generate tests automatically. Every rule is directly a property test generating thousands of cases.
• Rules reveal missing features. Analysis often exposes operations you need but haven't designed.
• Rules catch contradictions early. Contradiction during design costs minutes; in production, days.