Kotlin 1.0 Beta 2 is Out!

Posted on November 16, 2015 by Andrey Breslav

The first update to our Beta is here! We are stabilizing, so it’s mostly bug-fixing and changes to the standard library.

Language changes

We are now enforcing single-instantiation inheritance constraint on type parameters: the same T can not have both List and List as its upper bounds. This has been always forbidden for classes, now the same check applies for type parameters.

Diagnostics were improved for the cases when a smart cast is impossible:

class C {
    var x: String? = ""
    fun foo(): String {
        if (x != null) return x // ERROR: smart cast to String is impossible, 
                                // because 'x' is a member variable
    }
}

class C {

var x: String? = ""

fun foo(): String {

if (x != null) return x // ERROR: smart cast to String is impossible,

// because 'x' is a member variable

}

Also, the compiler is now smart enough to warn us when a value is always null at a particular point:

    var x: Foo? = ...
    if (x != null) return
    x?.bar() // WARNING: bar() will never run, because x is always null here

var x: Foo? = ...

if (x != null) return

x?.bar() // WARNING: bar() will never run, because x is always null here

Library changes

We cleaning up the APIs of the standard library. Most visible changes this time concern ranges. We intended the common use cases such as “if (x in 1..10)” or “for (i in 1..10)” to remain without changes, but did some renaming and hierarchy rearrangements under the hoods:

Double and Float progressions are dropped
Byte and Short progressions are deprecated, the .. operator for bytes and shorts now returns IntRange
Range renamed to ClosedRange and its end property renamed to endInclusive
Progression is deprecated in favor of concrete progression implementations instead: IntProgression, LongProrgession, CharProgression
start and end properties in progressions are renamed to first and last

Then, utility extensions for strings were generalized to work with CharSequence where possible.

The filterIsInstance extension now requires an explicit specification of its type parameter:

foo(list.filterIsInstance()) // error: what is the type the checks are done for?!
foo(list.filterIsInstance<Bar>()) // OK: we are checking for Bar

foo(list.filterIsInstance()) // error: what is the type the checks are done for?!

foo(list.filterIsInstance<Bar>()) // OK: we are checking for Bar

NOTE: To reduce the size of the runtime library (which is especially important for Android applications), we removed the kotlin.dom and kotlin.browser packages from the standard library. They are now available as a separate library, kotlinx.dom. If you’re using any of these packages in your project, please add the new library as a dependency and update the import statements in your code (change kotlin.dom and kotlin.browser to kotlinx.dom and kotlinx.browser). Otherwise, the API of the library has not changed.

Other changes:

Added
- in-place reversing and sorting for MutableLists and Arrays
- naturalOrder and reverseOrder comparators
- mapNotNull, mapIndexedNotNull, filterIndexed
- String.toByte()
Deprecated (run Code Cleanup to migrate your code)
- Function.toGenerator
- toLinkedList
Dropped
- join, merge
- Delegates.lazy
- FileTreeWalk.filter, File.recurse, BufferedReader.lines and lineIterator
- assert, check and require with non-lazy message argument

Dokka

Dokka, the new documentation generation tool for Kotlin projects, has finally reached a full release. Dokka supports mixed-language projects and understands KDoc comments in Kotlin code and JavaDoc comments in Java code. Dokka has plugins for Gradle, Maven and Ant, so you can easily integrate it with the build system of your project. Download Dokka and find more information on the Dokka project site.

IDE changes

Completion now works for Java static members and members of objects. Just press Ctrl+Space for the second time:
Completion inside string templates has been added. For using it type "$name."
Now we can choose exact position of a breakpoint while debugging expressions with lambdas:
And finally, a bunch of intention actions have been added for importing Java statics, object members and enum entries. And there is an analogous one to *-import static members from Java classes or entries from enum classes

Installation

IntelliJ IDEA 15 and Android Studio will suggest you to update Kotlin automatically. If this does not happen, you can do it manually through Plugin Manager.

About Andrey Breslav

Andrey is the lead language designer of Kotlin at JetBrains.

View all posts by Andrey Breslav →

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36 Responses to Kotlin 1.0 Beta 2 is Out!

Даниил Водопьян says:

November 16, 2015 at 9:34 pm

What’s with Delegates.lazy? What went wrong with it and what to use instead?
- Roman Belov says:
  
  November 16, 2015 at 9:38 pm
  
  Simply, lazy
  https://kotlinlang.org/docs/reference/delegated-properties.html
  - Даниил Водопьян says:
    
    November 16, 2015 at 9:41 pm
    
    That’s cool! Wanted that for a long time!
    Is Delegates.observable() still in stdlib, or the docs are wrong?
    - Sergey Mashkov says:
      
      November 16, 2015 at 9:52 pm
      
      Everything is fine both with stdlib and docs: https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.properties/-delegates/observable.html
Christian says:

November 16, 2015 at 9:47 pm

filterIndexed Finally!

String.toByte() is that a typo and should by toBytes()?
- ilya.gorbunov says:
  
  November 16, 2015 at 10:00 pm
  
  It’s a string-to-number conversion, like toInt(), toDouble() etc
- Sergey Mashkov says:
  
  November 16, 2015 at 10:01 pm
  
  String.toByte() is a function to parse a string as a number. To get bytes you need toByteArray
Niek Haarman says:

November 17, 2015 at 12:07 am

How should we handle the ClosedRange construct with the .. operator? Typing ‘1..2’ yields a Range, which is marked as deprecated. However, the following is not allowed:

testRange(1..2)

fun testRange(range: ClosedRange) {
}
- Andrey Breslav says:
  
  November 17, 2015 at 8:23 am
  
  1..2 yields IntRange. Your example works for me:
  
  fun test() { testRange(1..2) // No error } fun testRange(range: ClosedRange<Int>) { }
  
  1
  2
  3
  4
  5
  6
  7
  
  fun test() {
  testRange(1..2) // No error
  }
  
  fun testRange(range: ClosedRange<Int>) {
  }
  
  Please clarify your question.
Christian says:

November 17, 2015 at 11:38 am

Is there an online example of Dokka documentation?
- Sergey Mashkov says:
  
  November 17, 2015 at 12:45 pm
  
  Sure. Kotlin’s API reference has been generated by Dokka: https://kotlinlang.org/api/latest/jvm/stdlib/index.html
  - Sergey says:
    
    November 17, 2015 at 1:33 pm
    
    On page https://kotlinlang.org/api/latest/jvm/stdlib/index.html link “kotlin” refers to a https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/index.md that is not found (404). Probably should refer to page https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/.
  - Karol Stasiak says:
    
    November 17, 2015 at 3:47 pm
    
    Most links go 404 for me.
  - Max M. says:
    
    November 17, 2015 at 4:15 pm
    
    All link currently run into a 404. Are you maybe updating ATM?
    
    Eg: http://kotlinlang.org/api/latest/jvm/stdlib/kotlin/index.md
  - Andrey Breslav says:
    
    November 17, 2015 at 5:42 pm
    
    Links have been fixed. Thanks for the report
Pingback: Yested FW was updated to Kotlin Beta 2. | Yested Framework
changmin.jeon says:

November 17, 2015 at 7:25 pm

While coding android application, the following code cause error after Kotlin’s plugins were updated.
var intent = Intent(this, BGMService::class.java)
Error:(72, 30) None of the following functions can be called with the arguments supplied:
public constructor Intent(packageContext: android.content.Context!, cls: java.lang.Class<*>!) defined in android.content.Intent
public constructor Intent(action: kotlin.String!, uri: android.net.Uri!) defined in android.content.Intent
- yanex says:
  
  November 17, 2015 at 8:47 pm
  
  It works for me. Can you provide some more details? Slack or email (yan.zhulanow[at]jetbrains.com) is also ok.
  - changmin.jeon says:
    
    November 18, 2015 at 5:33 pm
    
    It’s working. It was my mistake. sorry for confusing your team.
Tonisi says:

November 18, 2015 at 12:05 am

Well done team.

Any chance Kotlin will support union types as TypeScript and Ceylon does? It’s really useful.
- Andrey Breslav says:
  
  November 18, 2015 at 1:40 pm
  
  We are looking for ways of supporting something like union types for JavaScript interop
  - Tonisi says:
    
    November 18, 2015 at 1:49 pm
    
    That’s amazing news. Will this include flow sensitive typing?
    - Andrey Breslav says:
      
      November 18, 2015 at 3:18 pm
      
      Not sure. We’ll see
Alexey Romanov says:

November 20, 2015 at 11:12 am

Why are Byte and Short progressions deprecated?
Pingback: Entreprenorskapital » RoboVM 1.11 released – experimental Bitcode support, iOS 9 and Kotlin!
Pingback: Entreprenorskapital » RoboVM 1.11 released – experimental Bitcode support, iOS 9.1 and Kotlin!
Takuya Miyamoto says:

November 21, 2015 at 7:35 pm

Android Studio 1.5 complains the following:

12:33:45 AM Plugin Error: Kotlin threw an uncaught AssertionError. Disable Plugin
12:33:45 AM AssertionError: Recursion detected on input: onCreate under LockBasedStorageManager@2ca87264 (org.jetbrains.kotlin.idea.caches.resolve.GlobalContextUtilsKt.withCompositeExceptionTrackerUnderSameLock(globalContextUtils.kt:27))
- Takuya Miyamoto says:
  
  November 21, 2015 at 7:39 pm
  
  The stacktrace is here.
  
  Recursion detected on input: onCreate under LockBasedStorageManager@4d04582c (org.jetbrains.kotlin.idea.caches.resolve.GlobalContextUtilsKt.withCompositeExceptionTrackerUnderSameLock(globalContextUtils.kt:27))
  java.lang.AssertionError: Recursion detected on input: onCreate under LockBasedStorageManager@4d04582c (org.jetbrains.kotlin.idea.caches.resolve.GlobalContextUtilsKt.withCompositeExceptionTrackerUnderSameLock(globalContextUtils.kt:27))
  at org.jetbrains.kotlin.load.java.lazy.descriptors.LazyJavaScope.getContributedFunctions(LazyJavaScope.kt:216)
  at org.jetbrains.kotlin.resolve.jvm.kotlinSignature.SignaturesPropagationData.getSuperFunctionsForMethod(SignaturesPropagationData.java:308)
  at org.jetbrains.kotlin.resolve.jvm.kotlinSignature.SignaturesPropagationData.(SignaturesPropagationData.java:88)
  at org.jetbrains.kotlin.load.java.components.TraceBasedExternalSignatureResolver.resolvePropagatedSignature(TraceBasedExternalSignatureResolver.java:63)
  at org.jetbrains.kotlin.load.java.lazy.descriptors.LazyJavaClassMemberScope.resolveMethodSignature(LazyJavaClassMemberScope.kt:425)
  at org.jetbrains.kotlin.load.java.lazy.descriptors.LazyJavaScope.resolveMethodToFunctionDescriptor(LazyJavaScope.kt:123)
  at org.jetbrains.kotlin.load.java.lazy.descriptors.LazyJavaScope$functions$1.invoke(LazyJavaScope.kt:82)
  at org.jetbrains.kotlin.load.java.lazy.descriptors.LazyJavaScope$functions$1.invoke(LazyJavaScope.kt:54)
  at org.jetbrains.kotlin.storage.LockBasedStorageManager$MapBasedMemoizedFunction.invoke(LockBasedStorageManager.java:389)
  at org.jetbrains.kotlin.storage.LockBasedStorageManager$MapBasedMemoizedFunctionToNotNull.invoke(LockBasedStorageManager.java:453)
  at org.jetbrains.kotlin.load.java.lazy.descriptors.LazyJavaScope.getContributedFunctions(LazyJavaScope.kt:216)
  at org.jetbrains.kotlin.idea.caches.resolve.JavaResolutionUtils.resolveMethod(JavaResolveExtension.kt:96)
  at org.jetbrains.kotlin.idea.caches.resolve.JavaResolutionUtils.getJavaMethodDescriptor(JavaResolveExtension.kt:43)
  at org.jetbrains.kotlin.idea.caches.resolve.JavaResolutionUtils.getJavaMethodDescriptor$default(JavaResolveExtension.kt:37)
  at org.jetbrains.kotlin.idea.search.ideaExtensions.KotlinPropertyAccessorsReferenceSearcher.propertyName(KotlinPropertyAccessorsReferenceSearcher.kt:55)
  at org.jetbrains.kotlin.idea.search.ideaExtensions.KotlinPropertyAccessorsReferenceSearcher.processQuery(KotlinPropertyAccessorsReferenceSearcher.kt:37)
  at org.jetbrains.kotlin.idea.search.ideaExtensions.KotlinPropertyAccessorsReferenceSearcher.processQuery(KotlinPropertyAccessorsReferenceSearcher.kt:34)
  at com.intellij.openapi.application.QueryExecutorBase$2.run(QueryExecutorBase.java:44)
  at com.intellij.openapi.application.impl.ApplicationImpl.runReadAction(ApplicationImpl.java:867)
  at com.intellij.openapi.application.QueryExecutorBase.execute(QueryExecutorBase.java:42)
  at com.intellij.util.ExecutorsQuery.processResults(ExecutorsQuery.java:43)
  at com.intellij.util.AbstractQuery.forEach(AbstractQuery.java:75)
  at com.intellij.util.MergeQuery.processSubQuery(MergeQuery.java:84)
  at com.intellij.util.MergeQuery.forEach(MergeQuery.java:56)
  at com.intellij.util.UniqueResultsQuery.process(UniqueResultsQuery.java:66)
  at com.intellij.util.UniqueResultsQuery.forEach(UniqueResultsQuery.java:56)
  at com.intellij.find.findUsages.JavaFindUsagesHelper.addElementUsages(JavaFindUsagesHelper.java:604)
  at com.intellij.find.findUsages.JavaFindUsagesHelper.processElementUsages(JavaFindUsagesHelper.java:139)
  at com.intellij.codeInsight.daemon.impl.UnusedSymbolUtil.processUsages(UnusedSymbolUtil.java:265)
  at com.intellij.codeInsight.daemon.impl.UnusedSymbolUtil.weAreSureThereAreNoUsages(UnusedSymbolUtil.java:168)
  at com.intellij.codeInsight.daemon.impl.UnusedSymbolUtil.isMethodReferenced(UnusedSymbolUtil.java:148)
  at com.intellij.codeInsight.daemon.impl.analysis.PostHighlightingVisitor.processMethod(PostHighlightingVisitor.java:440)
  at com.intellij.codeInsight.daemon.impl.analysis.PostHighlightingVisitor.processIdentifier(PostHighlightingVisitor.java:262)
  at com.intellij.codeInsight.daemon.impl.analysis.PostHighlightingVisitor.collectHighlights(PostHighlightingVisitor.java:199)
  at com.intellij.codeInsight.daemon.impl.analysis.HighlightVisitorImpl$3.run(HighlightVisitorImpl.java:184)
  at com.intellij.codeInsight.daemon.impl.analysis.RefCountHolder.analyze(RefCountHolder.java:308)
  at com.intellij.codeInsight.daemon.impl.analysis.HighlightVisitorImpl.analyze(HighlightVisitorImpl.java:177)
  at com.intellij.codeInsight.daemon.impl.GeneralHighlightingPass.analyzeByVisitors(GeneralHighlightingPass.java:297)
  at com.intellij.codeInsight.daemon.impl.GeneralHighlightingPass.access$200(GeneralHighlightingPass.java:64)
  at com.intellij.codeInsight.daemon.impl.GeneralHighlightingPass$4.run(GeneralHighlightingPass.java:300)
  at com.intellij.codeInsight.daemon.impl.DefaultHighlightVisitor.analyze(DefaultHighlightVisitor.java:86)
  at com.intellij.codeInsight.daemon.impl.GeneralHighlightingPass.analyzeByVisitors(GeneralHighlightingPass.java:297)
  at com.intellij.codeInsight.daemon.impl.GeneralHighlightingPass.collectHighlights(GeneralHighlightingPass.java:266)
  at com.intellij.codeInsight.daemon.impl.GeneralHighlightingPass.collectInformationWithProgress(GeneralHighlightingPass.java:205)
  at com.intellij.codeInsight.daemon.impl.ProgressableTextEditorHighlightingPass.doCollectInformation(ProgressableTextEditorHighlightingPass.java:97)
  at com.intellij.codeHighlighting.TextEditorHighlightingPass.collectInformation(TextEditorHighlightingPass.java:67)
  at com.intellij.codeInsight.daemon.impl.PassExecutorService$ScheduledPass$1$1.run(PassExecutorService.java:444)
  at com.intellij.openapi.application.impl.ApplicationImpl.tryRunReadAction(ApplicationImpl.java:1103)
  at com.intellij.codeInsight.daemon.impl.PassExecutorService$ScheduledPass$1.run(PassExecutorService.java:435)
  at com.intellij.openapi.progress.impl.CoreProgressManager.registerIndicatorAndRun(CoreProgressManager.java:452)
  at com.intellij.openapi.progress.impl.CoreProgressManager.executeProcessUnderProgress(CoreProgressManager.java:402)
  at com.intellij.openapi.progress.impl.ProgressManagerImpl.executeProcessUnderProgress(ProgressManagerImpl.java:54)
  at com.intellij.codeInsight.daemon.impl.PassExecutorService$ScheduledPass.doRun(PassExecutorService.java:432)
  at com.intellij.codeInsight.daemon.impl.PassExecutorService$ScheduledPass.run(PassExecutorService.java:408)
  at com.intellij.concurrency.JobLauncherImpl$VoidForkJoinTask.exec(JobLauncherImpl.java:189)
  at jsr166e.ForkJoinTask.doExec(ForkJoinTask.java:260)
  at jsr166e.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:858)
  at jsr166e.ForkJoinPool.scan(ForkJoinPool.java:1687)
  at jsr166e.ForkJoinPool.runWorker(ForkJoinPool.java:1642)
  at jsr166e.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:109)
- Andrey Breslav says:
  
  November 21, 2015 at 7:53 pm
  
  Please submit bug reports to the issue tracker: https://youtrack.jetbrains.com/issues/KT

Agustin says:

December 4, 2015 at 6:12 am

Well done!.

Would be possible to add preprocessor conditional compilation? Like C++ #ifdef would be awesome!.

Andrey Breslav says:

December 4, 2015 at 4:32 pm

What is your use case for #ifdef?

Agustin says:

December 5, 2015 at 2:47 am

I’m writting an agnostic OpenGL engine (using Kotlin) and i was thinking on doing something like this:

public class enum Attribute
{
// Desktop.
#ifdef TARGET_OPENGL
HALF_FLOAT = GL_HALF_FLOAT

  //  Mobile.

1 2	// Mobile.

#else defined(TARGET_OPENGL_ES)
HALF_FLOAT = GL_HALF_FLOAT_OES

   //  Javascript WebGL

1 2	// Javascript WebGL

#else defined (TARGET_WEBGL)
#endif
}

Andrey Breslav says:

December 7, 2015 at 4:23 pm

Kotlin enums do not support things like HALF_FLOAT = GL_HALF_FLOAT, but you can use simple val‘s for that.

Agustin says:

December 8, 2015 at 3:43 am

I actually wrote the example wrong.

public class enum Attribute(public val eID)
{
#ifdef TARGET_OPENGL
HALF_FLOAT(GL.GL_HALF_FLOAT)
#elseif defined(TARGET_OPENGLES)
HALF_FLOAT(GL.GL_HALF_FLOAT_OES)
#endif
}

Andrey Breslav says:

December 8, 2015 at 1:40 pm

Ok, now I see, thanks.

Andrey Breslav says:

December 8, 2015 at 1:43 pm

You can do this without #ifdef. Let’s say that TARGET_OPENGL is a simple boolean constant, then we can say

public class enum Attribute(public val eID) {
    HALF_FLOAT(
        if (TARGET_OPENGL) GL.GL_HALF_FLOAT 
        else if (GL.GL_HALF_FLOAT_OES) GL.GL_HALF_FLOAT_OES 
        else ...)
}

public class enum Attribute(public val eID) {

HALF_FLOAT(

if (TARGET_OPENGL) GL.GL_HALF_FLOAT

else if (GL.GL_HALF_FLOAT_OES) GL.GL_HALF_FLOAT_OES

else ...)

}

The only thing that can not be done this way is adding/removing a constant depending on a condition

Comments are closed.

Kotlin 1.0 Beta 2 is Out!

Language changes

Library changes

Dokka

IDE changes

Installation

About Andrey Breslav

36 Responses to Kotlin 1.0 Beta 2 is Out!

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