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Result of IndexedSeq.view is not an IndexedSeq #10103

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scabug opened this issue Dec 11, 2016 · 5 comments
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Result of IndexedSeq.view is not an IndexedSeq #10103

scabug opened this issue Dec 11, 2016 · 5 comments
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@szeiger
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enhancement has PR library:collections
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2.13.0-RC1

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@scabug
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scabug commented Dec 11, 2016 

Welcome to Scala 2.12.1 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_111).
Type in expressions for evaluation. Or try :help.

scala> :paste
// Entering paste mode (ctrl-D to finish)

val ints: IndexedSeq[Int] = Vector(1, 2, 3, 4)
val view: IndexedSeq[Int] = ints.view(1, 3)

// Exiting paste mode, now interpreting.

<pastie>:12: error: type mismatch;
 found   : scala.collection.SeqView[Int,IndexedSeq[Int]]
 required: IndexedSeq[Int]
       val view: IndexedSeq[Int] = ints.view(1, 3)
                                            ^

Seems like in a perfect world, a view over an IndexedSeq would be an IndexedSeq.
@scabug
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scabug commented Dec 11, 2016

Imported From: https://issues.scala-lang.org/browse/SI-10103?orig=1
Reporter: Ryan Williams (rdub)
Affected Versions: 2.12.1

@scabug
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scabug commented Dec 12, 2016

@szeiger said:
The latest strawman proposals for the new collections design take this into account.

@scabug scabug added this to the 2.13.0-RC1 milestone Apr 7, 2017
@szeiger
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szeiger commented Jan 9, 2019

It's supposed to be an IndexedSeqView in 2.13 but it's actually broken:

Welcome to Scala 2.13.0-20190107-124924-eeea070 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_172).
Type in expressions for evaluation. Or try :help.

scala> val ints: IndexedSeq[Int] = Vector(1, 2, 3, 4)
ints: IndexedSeq[Int] = Vector(1, 2, 3, 4)

scala> val view: scala.collection.IndexedSeqView[Int] = ints.view(1, 3)
                                                                 ^
       error: type mismatch;
        found   : scala.collection.View[Int]
        required: scala.collection.IndexedSeqView[Int]

IndexedSeqOps has the required override. This must be a compiler bug.

@Jasper-M
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Jasper-M commented Jan 9, 2019

IndexedSeqOps has the required override. This must be a compiler bug.

It doesn't. view is overriden. view(from: Int, until: Int) is not overridden and is deprecated in IterableOps.

@adriaanm adriaanm self-assigned this Jan 9, 2019
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szeiger commented Jan 9, 2019

Oh, you're right. I'll add some overrides then.

szeiger added a commit to szeiger/scala that referenced this issue Jan 9, 2019
@szeiger
Add IndexedSeqView overrides for view(from, until)
20b6d15 
Fixes scala/bug#10103
@szeiger szeiger mentioned this issue Jan 9, 2019
Merged
@szeiger szeiger added the has PR label Jan 9, 2019
@szeiger szeiger assigned szeiger and unassigned adriaanm Jan 9, 2019
szeiger added a commit to szeiger/scala that referenced this issue Jan 22, 2019
@szeiger
Add IndexedSeqView overrides for view(from, until)
b6af0d2 
Fixes scala/bug#10103
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@szeiger @adriaanm @SethTisue @Jasper-M @scabug