Kotlin 1.0.0 Beta 2

What's New

• Language
  • Single-instantiation inheritance for type parameters
  • More precise "smart cast impossible" (the reason is given now)
  • "Always null" warningadded
• Library
  • Ranges
    • Double and Float progressions are dropped
    • Byte and Short progressions are deprecated, the .. operator for bytes and shorts now returns IntRange
    • Range<T> renamed to ClosedRange<T> and its end property renamed to endInclusive
    • Progression<T> is deprecated in favor of concrete progression implementations instead: IntProgression, LongProrgession, CharProgression
    • start and end properties in progressions are renamed to first and last
  • kotlin.dom and kotlin.browser moved out as a separate library: kotlinx.dom
  • Strings/CharSequences
    • String utility extensions were generalized to take CharSequence where possible
  • Added
    • in-place reversing and sorting for MutableLists and Arrays
    • naturalOrder and reverseOrder comparators
    • mapNotNull, mapIndexedNotNull, filterIndexed
    • String.toByte()
  • Сhanged
    • Explicit type parameter specification for filterIsInstance now is required
  • Deprecated
    • 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
• IDE
  • Completion of java static members and members from objects on second Ctrl-Space
  • Intention action to import Java statics, object members or enum entries
  • Intention action to import all Java static members from the given class or enum entries from the given enum class
  • Completion in string templates works after "$name."
  • Debugger supports choosing where to put a breakpoint: inside or outside a single-lined lambda

Kotlin 1.0. Beta

Bug fixes

• Semantics of companion object initialization fixed, INSTANCE field deprecated for companion objects
• Use-site targets fixed for @JvmName
• Exposing Java package-private types through internal declarations is allowed
• Access to Enum.values from within enums fixed
• Issues with Android 4 and DefaultImpls classes fixed
• Method count optimized for delegated properties on Android
• Two main() functions can't appear in the same file

Kotlin 1.0.0 Beta Candidate

Language

• Imports from objects
• @Deprecated supports ERROR and HIDDEN levels (@HiddenDeclaration is deprecated)
• Smart casts for captured local var's that are not modified in lambdas
• Single-file classes can have many main()'s
• internal visibility checked in the compiler
• No defensive copying needed for varargs
• All Java methods with matching signatures are operators
• Rename: unaryMinus/unaryPlus for unary operators
• Rename: getValue/setValue for delegated properties
• Checks for operator signatures at declarations sites
• infix modifier for infix functions
• Rename sparam annotation target to setparam
• @UnsafeVariance annotation
• fun foo<T>() deprecated in favor of fun <T> foo()
• Constraints on type parameters should occur either in where or in <…>
• x is Array<Foo> forbidden in favor of x is Array<*> && x.isArrayOf<Foo>()
• Callable references restricted to support bound references later
• PropertyMetadata deprecated in favor of KProperty<*>
• if with no else in expression position is an error
• Letters and digits right before/after string and char literals are prohibited
• invoke convention for extension functions is removed
• Visibility requirements for members
• Protected members in objects are prohibited
• final in interfaces is prohibited
• Visibility for local classes is prohibited
• Local interfaces are prohibited
• Private setters for non-private lateinit vars are prohibited
• Nothing-returning functions must declare return type explicitly
• Annotations on multi-declarations are prohibited
• Checks for escaped identifiers (backticks) to conform to JVM requirements
• Supertypes of the form T.() -> Foo are prohibited
• Foo<Int>.Bar is prohibited
• Type parameters for properties are prohibited unless they are used in the receiver type
• Parameter annotations and default values in function types are prohibited
• inline properties are prohibited
• ;; is reserved for future use

Libraries

• Formerly deprecated declarations have been dropped
• size(), length() etc are made properties
• List.remove(int) is renamed to removeAt
• Collection<E>.contains(Any?), Map<K, V>.get(Any?) and other similar function are now type-safe: contains(E), get(K)
• containsRaw, getRaw extensions and alike are defined for the Java-like utyped behavior
• Regex API changes: matchEntire added, match/matchAll renamed to find/findAll, also regex in string can be used isntead of regex.hasMatch(string)
• listOf() doesn't make a defensive copy
• StringBuilder {} function deprecated in favor of buildString {}
• Rename: merge -> zip, join removed (use joinToString), mapNotNull deprecated to be changed later

Java interop

• Java classes inherit static from supertypes
• List<Nothing> is compiled to raw List to facilitate subtyping in Java
• Support "static overrides" for Java fields
• Top-level privates are private to file
• Names of internal functions and properties are mangled
• Kotlin classes see inherited statics and members of inherited companion objects
• @Synchronized and @Volatile are inapplicable to unimplemented functions
• isFoo() instead of getIsFoo() for properties named isFoo
• Old package facades are dropped
• Inheritance rules comply with Java 8
• is distinguishes MutableList from List and supports functions of different arities
• Int, String and other basic types are Serializable
• @JvmField is required to make something a field
• INSTANCE for objects (instead of INSTANCE$)
• Constant pool stings are resued to reduce metadata sizes
• @KotlinSignature is deprecated
• Java sees defaul implementations of methods in the interface Foo as statics in Foo.DefaultImpls class
• Constants from Java libraries are inlined into Kotlin byte code
• @publicField is deprecated

Tools

• Compiler daemon enabled by default in the IDE
• Parallel Compilation of Independent Modules in the daemon mode
• External annotations support removed

IDE

• Parameter Info everywhere
• Completion for callable references after ::
• Actions to generated equals()/hashCode()
• Actions to generate secondary constructors
• '*'-imports configuration
• Unit-testing support

Kotlin M14

What's new

• Language
  • New syntax for backing field access
  • Operators require a modifier (operator)
  • Compile-time constants are prefixed with const
  • Annotations on file classes supported
  • private on the top level is now private to file
  • internal is checked in the compiler (not only IDE)
  • private in interfaces is truly private now
  • equals in data classes compares arrays by calling their .equals() method (which works by identity)
  • lateinit val‘s are prohibited
  • many cases of inheritance and other degrees of freedom are prohibited for data classed (see this blog post)
  • protected and internal members are prohibited in interfaces
  • _, __, ___ are forbidden as in identifiers
  • identityEquals() function is deprecated in favor of ===
• Standard Library API subdivided into part classes such as CollectionsKt
• IDE
  • Introduce backing property refactoring
  • Move property initializer to declaration refactoring
  • Add unambiguous imports on-the-fly
  • Completion for overridden members

Kotlin M13 bugfix update

Bugfix update to 0.13.1513

• ProGuard issues fixed

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

M12 bugfix update

build-0.12.613

M12 bugfix update

build-0.12.412

Kotlin M12

What's New

• Language
  • @-based annotation syntax
  • New label syntax (name@)
  • KClass instead of java.lang.Class used in annotations
  • constructor keyword in primary constructors
  • trait replaced with interface
  • New syntax for enums: delimiters and constructor calls
  • Unified Function types
  • Smart casts for local var's
  • Smart casts for public/protected val's within the same module
  • Inlining and non-local returns for function expressions
  • Deprecations/Removals:
    • break and continue in when
    • interfaces that extend classes
    • covariant supertype specialization
    • static type assertions
• Java Interop
  • Source maps (JSR-45) for better debugging of inline functions
  • Initial support for Annotation Processing (JSR-269)
  • [deprecation] Only value can be passed as positional to Java annotations
• JavaScript
  • Inlining works between modules
  • Reified parameters
  • Function expressions
  • Secondary constructors
• JUnit support in Gradle plugin for Android
• Standard Library
  • kotlin.io
  • new text utilities
  • regular expressions API unified across JVM and JS
  • new collections utilities
  • full list available here
• IntelliJ IDEA Plugin
  • Introduce Parameter
  • Introduce Lambda Parameter
  • Rename for related declarations (variables, subclasses)
  • @ReplaceWith annotation for deprecated declarations
  • Debugger
    • Evaluate expression for local functions
    • Field Watch Points (only for properties with backing field)
  • Change Package Intention
  • Highlighting exit points of functions
  • Gutter Marks for recursive calls
  • Unused receiver parameter
  • Code style settings for imports (e.g. we can now always import specified packages with '*')
  • Java2Kotlin Converter now offers to update usages in other files
  • Typing '!' when completion list is open inserts negated call (e.g. !foo.isEmpty())
  • Intention actions to change visibility modifiers
  • Intention actions have much better scope of availability now
  • Quick-fix to add parameters from the base class when the superclass' constructor has parameters

Kotlin M11.1

Bugfix update