added a first spike of the collection-like methods based on this doc http://confluence.jetbrains.net/display/JET/Standard+Library

stdlib/ktSrc/JavaUtil.kt

@@ -2,8 +2,102 @@ namespace std.util
 
 import java.util.*
 
+/** Returns the size of the collection */
 val Collection<*>.size : Int
     get() = size()
 
+/** Returns true if this collection is empty */
 val Collection<*>.empty : Boolean
     get() = isEmpty()
+
+/** Returns a new ArrayList with a variable number of initial elements */
+fun arrayList<T>(vararg values: T) : ArrayList<T> {
+  val answer = ArrayList<T>()
+  for (v in values)
+    answer.add(v)
+  return answer;
+}
+
+/** Returns a new HashSet with a variable number of initial elements */
+fun hashSet<T>(vararg values: T) : HashSet<T> {
+  val answer = HashSet<T>()
+  for (v in values)
+    answer.add(v)
+  return answer;
+}
+
+/** Returns a new collection for the results of a helper method */
+protected fun <T,R> java.lang.Iterable<T>.create(defaultSize: Int? = null) : Collection<R> {
+  if (defaultSize != null) {
+    return ArrayList<R>(defaultSize)
+  } else {
+    return ArrayList<R>()
+  }
+}
+
+protected fun <T,R> Set<T>.create(defaultSize: Int? = null) : Set<R> {
+  if (defaultSize != null) {
+    return HashSet<R>(defaultSize)
+  } else {
+    return HashSet<R>()
+  }
+}
+
+
+
+/** Returns true if any elements in the collection match the given predicate */
+fun <T> java.lang.Iterable<T>.any(predicate: fun(T): Boolean) : Boolean {
+  for (elem in this) {
+    if (predicate(elem)) {
+      return true
+    }
+  }
+  return false
+}
+
+/** Returns true if all elements in the collection match the given predicate */
+fun <T> java.lang.Iterable<T>.all(predicate: fun(T): Boolean) : Boolean {
+  for (elem in this) {
+    if (!predicate(elem)) {
+      return false
+    }
+  }
+  return true
+}
+
+/** Returns the first item in the collection which matches the given predicate or null if none matched */
+fun <T> java.lang.Iterable<T>.find(predicate: fun(T): Boolean) : T? {
+  for (elem in this) {
+    if (predicate(elem))
+      return elem
+  }
+  return null
+}
+
+/** Returns a new collection containing all elements in this collection which match the given predicate */
+// TODO using: Collection<T> for the return type - I wonder if this exact type could be
+// deduced somewhat from the This.Type; e.g. returning Set on a Set, Array on Array etc
+fun <T> java.lang.Iterable<T>.filter(predicate: fun(T): Boolean) : Collection<T> {
+  val result = this.create<T,T>()
+  for (elem in this) {
+    if (predicate(elem))
+      result.add(elem)
+  }
+  return result
+}
+
+/** Returns a new collection containing the results of applying the given function to each element in this collection */
+fun <T, R> java.lang.Iterable<T>.map(transform : fun(T) : R) : Collection<R> {
+  val result = this.create<T,R>()
+  for (item in this)
+    result.add(transform(item))
+  return result
+}
+
+/** Returns a new collection containing the results of applying the given function to each element in this collection */
+fun <T, R> java.util.Collection<T>.map(transform : fun(T) : R) : Collection<R> {
+  val result = this.create<T,R>(this.size)
+  for (item in this)
+    result.add(transform(item))
+  return result
+}