immutabilitást

Immutabilitás, or immutability in English, is the property of being unable to be changed after creation. In philosophy, it refers to the idea that certain entities or truths are constant and not subject to alteration, such as certain mathematical propositions or the traditional concept of a divine nature. In everyday language, immutability denotes lasting constancy over time.

Etymology traces immutability to Latin immutabūlis meaning not changeable, passing through French and English terms. In Hungarian, immutabilitás is the form of the concept, with immutable in accusative form as immutabilitást in grammatical usage.

In computing, immutability describes objects or data that cannot be modified once created. Instead of changing an existing object, a new object is produced with the desired updates. This approach underpins functional programming and persistent data structures, aiding reasoning about code and enabling safer concurrent execution. Techniques such as structural sharing and copy-on-write are commonly used to mitigate memory overhead. Immutable data structures are used in configuration management, caching, and undo mechanisms. In databases and logs, immutability is often enforced through append-only or write-once storage, supporting auditability and data integrity. In blockchain systems, blocks and transactions are designed to be immutable to preserve historical records and trust.

Advantages include simpler reasoning, avoidance of side effects, and easier multithreading. Trade-offs involve potential memory overhead and performance considerations, though modern implementations mitigate these issues with efficient sharing and lazy evaluation.

Legal and archival contexts view immutability as essential for evidence preservation, employing tamper-evident storage and write-once media. Examples accessible to the public include Git commits and blockchain entries, which demonstrate practical instantiations of immutability concepts. Criticism notes that immutability is not absolute; some systems implement logical immutability or require occasional controlled mutations for practicality.