Referential Transparency

Kind: principle

Layer: Computation Core

Record: architecture:referential-transparency

Severity: contextual

Scope: function, expression

Canonical: Ontology

A design rule that an expression can be replaced by its value without changing the program's behavior.

Listed in Architecture principles, after Predictability and before Pure Functions.

Requires

• Pure Functions
• Immutability

Reinforces

• Determinism
• Testability

Enables

• Safe Substitution

Conflicts with

• Side Effects

In tension with

• Stateful IO

Tensions

• Referential Transparency / Stateful IO

Violated by

• Hidden Time/Randomness/Global State

Refactored by

• Pure Functions
• Dependency Injection

Severity

• contextual

Category

• Correctness / Determinism / Verification

Linked from

• Computation and resource
• Correctness / Determinism / Verification
• Core Vocabulary
• Correctness / Determinism / Verification
• Severity levels
• The resolutions