Kotlin M13

What's New

• Language
  • lateinit properties
  • sealed classes
  • all annotations require @
  • annotation classes named starting with capital letter
  • some former annotations turned into modifiers (data, inline, noinline, tailrec, external, etc.)
  • annotation options: @Target, @Retention, @Repeatable, @MustBeDocumented
  • no requirement to specify return type explicitly for public
  • public by default
  • private on the top level means private to current source file
  • internal visibility checked between modules
  • overload resolution on callable references
  • unambiguous super-calls do not require angle brackets
• Java interop
  • Java get/set pairs are now seen as properties
  • New layout of class files: each source file is compiled to FileNameKt.class by default
  • @file:JvmName("ClassName") to customize the name of the class
  • @file:JvmMultifileClass to share the same class name across many files in the same package
  • @NotNull and @Nullable types loaded from Java
• Library
  • fully functional reflection
  • + and - for sets and other collections
  • improved delegates for properties
• Tools
  • compiler daemon keeps the compiler in memory between builds
  • incremental compilation is smarter with inline functions and privates
  • Java2Kotlin converter supports method references
• IntelliJ IDEA plugin
  • Pull Members Up/Down refactoring
  • Debugger support for lambdas and inline functions
  • Completion for parameter names and types
  • Highlighting for unused imports
  • Imports are optimized on-the-fly
  • New intentions for for loops