Why is there Immutable and Persistent separation i...
# stdlibp
PHondogo
07/27/2024, 10:49 PMWhy is there Immutable and Persistent separation in kotlinx-collections-immutable? Why not to keep only Immutable interface?
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Zach Klippenstein (he/him) [MOD]
07/27/2024, 11:21 PMThey mean different things. Immutable means your reference to the collection is guaranteed not to change. Persistent means that, when you change the structure by making a copy of it, parts of the data structure are reused.
Zach Klippenstein (he/him) [MOD]
07/27/2024, 11:21 PMImmutability is the more important guarantee for correctness, persistence is a memory and space optimization
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PHondogo
07/28/2024, 12:17 AMHello, Zach!
What do you mean by saying: parts of the data structure are reused?
Isn't it implementation details (but both are interfaces)? As i thought both Immutable and Persistent collections make guarantee that they can't be modified.
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ephemient
07/28/2024, 3:45 AMthe way persistent collections are implemented come with different complexity trade-offs than immutable collections that do not need to be persistent
ephemient
07/28/2024, 3:47 AMthe library doesn't currently make use of that, but it's in the roadmap to figure out https://github.com/Kotlin/kotlinx.collections.immutable/issues/185
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PHondogo
07/28/2024, 9:23 AM@ephemient thanks for the link!
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ilya.gorbunov
08/12/2024, 10:41 AM9 Views