Immutability (computer science)

Immutability isn't a well known concept among the (imperative) languages, which readers of this blog might be more familiar with. In fact, these languages are mainly built around its opposite, mutability - the ability to define data, pass it around via references/pointers and then change it (usually impacting multiple places of the codebase). The fact, that immutable data is read-only once it's been defined, provides the key feature for truly enabling safe multi-threaded applications and simplifies other programming tasks (e.g. easy comparison of nested values, general testability and the ability to safely reason over a function's behaviour). The presence of immutable data also leads to fundamental questions about the actual need for key topics in object oriented programming, e.g. the need for hiding data through encapsulation and all the resulting complexity is only required if a language doesn't provide features protecting data from direct 3rd party (i.e. user code) manipulation. This problem simply doesn't exist in Clojure! On the other hand immutability too provides one of the most challenging unlearning tasks for people coming from a world of mutable state, since it seems paradoxical to work it into any realworld system requiring constant changes to our data.

Saved 28 January 2014 / www.creativeapplications.net ↗

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