Kotlin 1.0.0 Beta 4

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Primary constructor is resolved in the same scope as secondary constructors
yield is reserved as a keyword
async is reserved in some contexts
typeof is reserved as a keyword. In JS, use jsTypeOf()
sealed when reserved
Multiple fixes in the overload resolution algorithm.
- The curious case of File.listFiles
KPropertyN now extend FunctionN, i.e. list.map(String::length) works now
Duplicate bounds for type parameters forbidden
Multiple class bounds for type parameters forbidden
Array<Nothing> and Array<Nothing?> are prohibited
if with no else is not an expression
values() and valueOf() in enums are preferred to member of companion objects
Better scheme of translation of variant types to Java
@JvmSuppressWildards and @JvmWildcard added
Statics inherited by companion object are visible without qualification in the outer class and its subclasses
Absolute package references dropped. Use alias imports instead
Overloads are compared according to actual arguments only
Deprecations lifted to errors: Enum.values, local sealed classes, private setter for open property

kotlin-test.jar extracted
Extensions are moved to specific packages (no source changes required for Kotlin code)
javaPrimitiveType and javaObjectType added for KClass
IntArray(5) { it * 3 } and other initializers supported for primitive arrays
Semantics of null in maps is going to change
minWith(comparator)/maxWith(comparator) supported
toMap((T) -> Pair<K,V>)` supported
FileTreeWalk:
- constructor is deprecated, preferred construction with fluent builder methods
- treeFilter is deprecated, recursive filtering now happens in onStart
File utilities behavior changes and deprecations