Immutable Data Structures

The cluster focuses on debates about the performance, efficiency, and implementation of immutable data structures, including misconceptions about full copying and the use of persistent structures for structural sharing in languages like Haskell and Clojure.

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#7648
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Keywords

CPU JSON RCU OC JS AVL PureComponent wikipedia.org I.e OOP immutable data structures structures data mutable immutability mutability performance copy data structure

Sample Comments

viebel Dec 30, 2021 View on HN

Could you elaborate about the complexity involved in using immutable data structures in your use case? Is that a performance concern?

whateveracct Sep 13, 2024 View on HN

Fast immutable data structures don't rely on compiler optimizations. They just exist lol.

nesarkvechnep Apr 17, 2025 View on HN

No reason. OC probably thinks that immutable data structures are always copied when being operated on.

Scarbutt Dec 6, 2021 View on HN

Besides performance, what other cons exists for immutable data structures in a single standalone system?

Jaxan Oct 20, 2025 View on HN

Immutable does not mean you have to copy the whole structure. You can store only the changes. This is how immutable data structures work in functional languages such as Haskell.

ruleabidinguser Jun 30, 2017 View on HN

The immutable data structures example was revolting

Bahamut Dec 1, 2016 View on HN

Performance - immutability comes at a high cost sometimes.

better implement immutable data structures

eyelidlessness Jul 28, 2017 View on HN

Persistent data structures can generally overcome a lot of the performance issues with immutability, but generally at the cost of memory.

nik-graf Sep 18, 2015 View on HN

Does it also work with immutable data-structures?