Port TaskSeq.takeWhileInclusive

I'd like to see takeWhileInclusive (it has uses in Equinox) be ported from AsyncSeq.

Will post a PR to add it to the TODO list (and then one to implement it) in due course unless someone beats me to it, or there are objections to adding it...

Spike impl:

let TaskSeq_takeWhileInclusive predicate (source: taskSeq<_>) = taskSeq {
    use e = source.GetAsyncEnumerator(CancellationToken())
    let! step = e.MoveNextAsync()
    let mutable go = step
    while go do
        let value = e.Current
        yield value
        if predicate value then
            let! more = e.MoveNextAsync()
            go <- more
        else
            go <- false
}

(derived from Internal.tryPick + base impl )

In context: https://github.com/jet/equinox/blob/master/src/Equinox.Core/Internal.fs#L15-L45

@bartelink

Thanks for your suggestion @bartelink! So this is like “get next, yield that, test predicate on that one, if true, repeat”. That is, return element first, before testing predicate.

Interesting function. I was about to add a whole section (just like I did for seq) listing all functions that I’ll implement and which (likely) not.

Your proposal looks good, as does the code, feel free to issue a PR, it’ll need to have matching tests (I’m a little more rigorous than the AsyncSeq team in that regard and need notable corner cases), but I can help you with that.

Btw, it should probably be added together with takeWhile and both should be paired with an async version for the predicate function. I’m happy to help with that.

Thanks! Yes, I had noted that there was going to be no skimping on test coverage based on poking around ;)

But that's also why I confidently spent time converting Equinox and Propulsion over.

Won't get to the PR immediately but I'll get to it...

Does it make sense to also add a skipWhileInclusive(Async)? In a separate PR, of course. What do you think? It is not in AsyncSeq.

That does seem to make sense (although I'm struggling to think of a time I've ever had the use case), but arguably you'd call it skipUntil ?
Of course, that would call the name of takeWhileInclusive into question, but it makes less sense there.
On balance the Inclusive-based name both on the skip and the take sides is probably best overall considering someone scanning intellisense to find the right tool for a job?

but arguably you'd call it skipUntil ?

Seq has Seq.skipWhile and I like to stick with its naming conventions. They are each others opposites w.r.t. the predicate, so in the end I guess it is a matter of taste ;). See #130.

@bartelink

This issue was implemented in #126 and will be published in the next version of NuGet (be it 0.4.0 or 0.3.x). 💯 @bartelink

Seq has Seq.skipWhile and I like to stick with its naming conventions

On reflection, my suggestion doesn't make as much sense as it did in my head as I typed it. I was suggesting to replace the usage of the term WhileInclusive with Until, on the basis that it would naturally imply the Inclusive aspect. But I wasn't considering the fact that Until does mean inverting the predicate. Either way I was definitely not suggesting not providing a takeWhile, or having two functions that only differ by the fact that the predicate's meaning is inverted (I suffer enough mental anguish there being a filter and a where as it is!)

130 would be the better for removing any reference to Until (but commenting here to keep the noise down!)

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Port TaskSeq.takeWhileInclusive #122

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Port TaskSeq.takeWhileInclusive #122

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bartelink commented on Dec 8, 2022

abelbraaksma commented on Dec 10, 2022

abelbraaksma commented on Dec 10, 2022

bartelink commented on Dec 10, 2022

abelbraaksma commented on Dec 14, 2022

bartelink commented on Dec 14, 2022

abelbraaksma commented on Dec 14, 2022

abelbraaksma commented on Dec 14, 2022

bartelink commented on Dec 14, 2022

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