Type Safety

Kind: mechanism

Layer: Contracts Core

Record: architecture:type-safety

Severity: mandatory

Scope: function, module, API, data

Canonical: Ontology

A mechanism that has the compiler reject operations on values of the wrong type before the code runs.

Listed in Architecture principles, after Schema Validation and before Canonical Model.

Requires

• Explicit Types

Reinforces

• Correctness
• Contracts

Enables

• Static Analysis

Conflicts with

• Dynamic Untyped Boundaries
• Stringly Typed Programming

In tension with

• Rapid Scripting
• Composite Pattern
• Composite Pattern / Type Safety

Tensions

• Type Safety / Rapid Scripting

Violated by

• Dynamic Untyped Boundaries

Refactored by

• Narrow Type
• Introduce Boundary DTO

Severity

• mandatory

Category

• Schema / Canonical Data / Semantics

Enforced by

• rules/eslint/closure-discriminated-union-must-be-exhaustive.eslint.rule.ts
• rules/eslint/closure-no-double-cast.eslint.rule.ts
• rules/eslint/closure-no-null-managed-instance.eslint.rule.ts

Required by

• Explicit Contracts
• Data Contract

Reinforced by

• Liskov Substitution Principle
• Compile-Time Evaluation

Linked from

• A check matches a shape
• Anti-patterns
• Contracts / Interfaces / Compatibility
• Correctness / Determinism / Verification
• SOLID / Object-Oriented Design
• Metaprogramming / Language-Oriented Architecture
• Structural Patterns
• Contracts / Interfaces / Compatibility
• Core Vocabulary
• Schema / Canonical Data / Semantics
• Severity levels
• The resolutions