How are they different than: <https://github.com/Kotlin/kotlinx.collections.immutable>

# announcements

[Arjan van Wieringen]

How are they different than: https://github.com/Kotlin/kotlinx.collections.immutable

[Asq]

immutable-kotlin is based on algebraic data types (e.g. functional sum types, an immutable list is built as list(a, cons)).  It also includes a larger menagerie of functional structures, all algebraic data types.

[Nir]

The problem is that an immutable list like that is simply a linked list

[Nir]

And tends to have really poor performance characteristics, e.g. does not provide proper random access which is a rather key part of the List API. What you typically see nowadays for a general purpose immutable list are trees of sorts that store mini arrays, and have branching factors of 32, something like that.

[Nir]

Immutable data structure implementations in general tend to get pretty complicated in practice because it tends to be very difficult to balance all the desirable performance characteristics

[Asq]

You described an immutable "array" in Scala 🙂. I'm well aware of that aspect of functional data structures. That is the reason I wondered if anyone is interested.

[Nir]

Indeed 🙂 I think the kotlinx implementation is based on that (though I could be wrong)

[Shawn]

see also #C1JMF6UDV, #C5UPMM0A0

[Asq]

Thanks, I will move to #C1JMF6UDV, it's probably a better home for this special interest subject.