Proposal. ```fun CharSequence.splitToSequences( ...

# stdlib

[Dominaezzz]

Proposal.

fun CharSequence.splitToSequences(
    vararg delimiters: String,
    ignoreCase: Boolean = false,
    limit: Int = 0
): Sequence<CharSequence>

[Hullaballoonatic]

yeah, i really want there to be a String::split method with all the params that Collection::joinToString has.

[Dominaezzz]

The existing splitToSequence returns String instead of CharSequence. Which means more allocations. 😞

[jimn]

CharSequence is worth avoiding performance-wise. it's a meaningless marker interface that requires workarounds in k-n to avoid O(n) access

[jimn]

adapting mappedbytebuffer to charsequence would be a good use for it.

[elizarov]

But why?

[Dominaezzz]

To be fair my current use case is quite specific. I have a large string of about 20,000 words separated by spaces and I want to count the number of occurrences of each word. I'm multi-threading. It's a bit rough to make large copies instead of slices.

[jimn]

i can think of at least a couple of libraries like suffix search trees that might find this applicable to Sequence<T> where the jvm implementations (and my kotlin port) vary between <T:Byte> and <T:Int>

[elizarov]

I’ve played with it at some point, and, unfortunately, the version with sequences does not give any siginificant performance benefits.

[jimn]

nio ByteBuffer approximates c++ stl iterators for bytes where you get some tiny bit of hotspot love for a tight loop comparing values.

[miha-x64]

I'd like to see Iterators instead of Sequences 🤔

[Dominaezzz]

asIterator() solves that.

[miha-x64]

no-no-no, creating a redundant wrapper is a responsibility of a person who wants it: .toSequence()

[elizarov]

We try to avoid public APIs that return single-shot entities like Iterator. They are error-prone to work with. That is why Kotlin collections do not have any operators on iterators. Sequence is multi-use, thus easier to reason about, since it has not intrinsic “state” (used/not-used) that a person using it has to keep in mind.

[miha-x64]

But .constrainOnce() makes `Sequence`s even more unsafe.

[elizarov]

Yes. That is why I say “we try to”. There are some primitives that violate this rule, but they are limited. Same with Flow. Most of them multi-use with limited exceptions