kotlin inner closure example

InnerClosureExample.kt

fun countingLambda(): () -> Int {
    var counter = 0
    val incrementalCounter: () -> Int = {
        counter += 1
        counter
    }
    return incrementalCounter
}

// decompiled java
  @NotNull
  public static final Function0<Integer> countingLambda() {
      void counter;
      Ref.IntRef intRef = new Ref.IntRef();
      intRef.element = 0;
      Function0 incrementalCounter2 = (Function0)new Function0<Integer>((Ref.IntRef)counter){
          final /* synthetic */ Ref.IntRef $counter;

          public final int invoke() {
              ++this.$counter.element;
              return this.$counter.element;
          }
          {
              this.$counter = intRef;
              super(0);
          }
      };
      return incrementalCounter2;
  }