# Side Effects

> Producing observable side effects in an expression, so it cannot be replaced by its value.

Record: `lexicon:side-effects`
Kind: anti-pattern
Layer: [Computation Core](https://banes-lab.com/records/layer/computation-core.md)
Canonical: https://banes-lab.com/ontology/lexicon#lexicon-side-effects

Listed in [Lexicon terms](https://banes-lab.com/api/records/lexicon.md), after [Informal Validation Only](https://banes-lab.com/records/lexicon/informal-validation-only.md) and before [Unchecked Dynamic Code](https://banes-lab.com/records/lexicon/unchecked-dynamic-code.md).

## Category

- [Correctness / Determinism / Verification](https://banes-lab.com/records/lexicon-category/correctness-determinism-verification.md)

## Negated by

- [Referential Transparency](https://banes-lab.com/records/architecture/referential-transparency.md)

## Linked from

- [Correctness / Determinism / Verification](https://banes-lab.com/ontology/principles/architecture-category-correctness-determinism-verification.md)