Kotlin M8

What's new:

• JVM
  • Reflection for properties introduced
  • Inline functions
    • Inlines into objects are supported
    • Default parameter values supported for inline functions
  • Generated code speedups
    • delegated properties work faster now
    • when's with constants are faster due to dedicated bytecode instructions used
  • breaking change Reporting platform signature clashes
    • [platformName] annotation to resolve signature conflicts
  • transient, synchronized and strictfp supported on the JVM
• JS
  • data classes supported
  • LinkedHashSet/LinkedHashMap supported
• Language
  • breaking change private in a package now means "in this package and subpackages in the same module"
  • breaking change extension properties can't have backing fields
  • breaking change Bare @ and @@ are no longer available
• Standard library
  • slice()
  • collection-like operations on strings
  • Map.contains
  • join() for rendering separated lists
  • String.substringBefore/After[Last]
  • String.replaceBefore/After[Last]
  • Appendable.appendln()
  • StringBuilder {}
  • Iterable.merge(other) { (v1,v2)→v }
  • set operations (union, intersect, subtract)
• IDE
  • IntelliJ IDEA 14 EAP supported
  • Debugger
    • Evaluate expression
    • Smart step into
  • Refactorings
    • Move toplevel declarations to separate file
    • Extract function (not finished, but some cases working)
    • Extract local function
  • Intentions
    • DeMorgan law
    • Flip binary expression (== etc)
    • Split if
    • Replace with operator sign
    • Replace with traditional assignment
    • Replace with infix call
    • Simplify boolean expressions
    • Add/Remove explicit type arguments
    • assert <-> if with throw
    • if <-> ?:
    • !! <-> if
    • make types explicit/implicit in lambda
    • forEach { } <-> for loop
    • string concatenation <-> interpolation
  • Smart completion
    • smarter on overloads
    • callable references (::functionName)
    • lambdas
    • !! and ?: for nullable members
    • anonymous classes (object expressions)
    • constants in when()
  • Formatter improved
  • Structure view shows members of supertypes
  • J2K converter improved
  • Speedups in highlighting and completion
• Support for new versions of Gradle/Android (0.10, 0.11, 0.12)

Dot Operator

Release date: April 1, 2014

What's new

• The Dot operator, as described here
  Implemented here.

Limitations:

The following things are NOT implemented:

1. The higher-order dots. I find this feature quite specific and less useful in practice so I guess it can be put off for a while
2. Dot flavours. For me this feature looks rather confusing, so I suggest reconsidering whether it's worth implementing at all

Kotlin M7

What's new:

• Language
  • Inline functions
  • [breaking change] jet package renamed to kotlin
  • [breaking change] toString(), equals() and hashCode() are now members of Any
  • References to local functions
• Interop
  • [throws] annotation for JVM target
  • Overloading supported for JS target
• Standard Library
  • [breaking change] Streams introduced
• IDE enhancements
  • Rename/move refactorings improved
  • Safe delete
  • New intention actions
  • Performance improvements

Kotlin M6.2

What's new:

• Language features
  • Tail-call optimization with [tailRecursive]
  • Constant expression evaluation
  • Suffixes for Longs and Floats: 1L and 1.0F
• Compilation to JavaScript
  • Default arguments
  • Super-constructor calls
  • Class-objects in traits
• Java Inteoperability
  • @ReadOnly and @Mutable for collections
• Android
  • Better annotations for Android SDK
• IDE
  • Support for IntelliJ IDEA 13
  • Find Usages
  • Compiler preferences
  • Smart completion (Ctrl+Shift+Space)
  • Rename from Java
  • IDE warns on misusing Kotlin APIs from Java
• Ant
  • Integration with <javac>
  • Support for compilation to JavaScript

Kotlin M6.1

What's new:

• Language features
  • else is not required in when-statements
  • Type argument inference uses smart casts
  • Ability to suppress warnings with [suppress("...")] annotation
  • Local returns in lambda expressions
• Compilation to JavaScript
  • Enums
  • Class Objects
  • Delegated properties
  • Multi-Declarations
  • SourceMaps
• IntelliJ Plugin Improvements
  • Automatic configuration of Maven and Gradle projects
  • Convert member function to extension function
  • Navigation to getters and setters of a delegated property
  • Navigation to iterator/next/hasNext in a for loop
  • Navigation to invoke() from a call site
  • Improvements on Find Usages including support for constructors and overrides

Read more in this blog post

Kotlin M6

What's new:

• Language features
  • SAM Conversions
  • Annotation improvements
  • Static fields visible from Java
• Android
  • Integration with Gradle for Android
  • Integration with Android Studio
• IDE features
  • Inline variable, Safe delete and other refactorings
  • TestNG support
  • Faster code completion

See a detailed description in this blog post.