items.list.filter {}.map { it.depth }.max() ?: -1

?.apply

?.also

?: run {
    …
    null
}

?: null.apply { ... }

null

inline fun <T> T.alsoIfNull(block: () -> Unit): T {
    if (this == null) {
        block()
    }
    return this
}

String[] split = log.split(" ", 2);

"asd".split(" ", 2)

// base module provides registry
interface Feature

private val availableFeatureTypes = hashSetOf<String>()

inline fun <reified TFeature: Feature> registerFeature(feature: TFeature) {
    availableFeatureTypes.add(typeNameOf<TFeature>())
    // …
}
inline fun <reified TFeature: Feature> isFeatureAvailable() =
    availableFeatureTypes.contains(typeNameOf<TFeature>()) // no 'NoClassDefFoundError' because inlined


// a module providing `SomeFeature` registers it by fully qualified name
object SomeFeature: Feature

fun someFunThatGetsCalledIfModuleIsUsed() {
   registerFeature(SomeFeature)
}


// another module can optionally depend on SomeFeature
if (isFeatureAvailable<SomeFeature>()) { // no 'NoClassDefFoundError' because inlined
    val feature = SomeFeature() // executed only if SomeFeature is available
    // …
}

{
  "foo": "bar",
  "scores": [
    {
      "name": "foo",
      "score": 0
    },
    {
      "name": "bar",
      "score": 10
    },
    {
      "name": "foobar",
      "score": 50
    },
    {
      "name": "name",
      "score": 20
    }
  ]
}

{
  "foo": "bar",
  "scores": [
    {
      "name": "foo"
    },
    {
      "name": "bar"
    },
    {
      "name": "foobar",
      "high_score": true
    },
    {
      "name": "name"
    }
  ]
}

toInt

toIntOrNull

kotlin.text

String

CharSequence

ArrayList

removeIf

hashSetOf()

toHashSet()

Set

hashMapOf()

toHashMap()

Map

toSortedMap()

CharSequence.indexOfLast

String

Char

lastIndexOf

CaseFormat

false

resettableLazy

// do not introduce this overload --- too rare
//public fun <T, K> List<T>.binarySearchBy(key: K, comparator: Comparator<K>, fromIndex: Int = 0, toIndex: Int = size(), selector: (T) -> K): Int =
//        binarySearch(fromIndex, toIndex) { comparator.compare(selector(it), key) }