Add TraversableOnce.knownSize #143
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MasseGuillaume
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julienrf
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Aug 7, 2018
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Let's put this PR on hold: scala/bug#11065. It looks like |
julienrf
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Aug 9, 2018
| class ExtensionsTest { | ||
| @Test | ||
| def `TraversableOnce.knownSize`(): Unit = { | ||
| Assert.assertEquals(-1, Iterator(1).knownSize) |
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In 2.13 the size of an IndexedSeq’s iterator is known: https://github.com/scala/scala/blob/2.13.x/src/library/scala/collection/IndexedSeqView.scala#L27
You can use Iterator.from(1) instead.
| @Test | ||
| def `TraversableOnce.knownSize`(): Unit = { | ||
| Assert.assertEquals(-1, Iterator(1).knownSize) | ||
| Assert.assertEquals(1, List(1).knownSize) |
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The size of LinearSeqs is not known in 2.13.
Actually I realize only now that hasDefiniteSize has nothing to do with the fact that the size of the collection is cheaply computable. It only tells us whether the collection is finite or infinite. Consequently, this is not the correct way to implement knownSize. I’m not sure there is a correct way.
martijnhoekstra
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Nov 9, 2022
it isn't obvious to me from the git history how/why this even was there in the first place
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