A Kotlin DSL for AutoCloseable

AutoClose.kt

import arrow.atomic.Atomic
import arrow.atomic.update

/**
  * AutoClose offers DSL style API for creating parent-child relationships of AutoCloseable dependencies
  */
interface AutoClose : AutoCloseable {
  fun <A : AutoCloseable> autoClose(autoCloseable: A): A
}

/** DSL method to use AutoClose */
fun <A> autoClose(block: AutoClose.() -> A): A =
  AutoClose().use(block)
  
/**
  * Constructor for AutoClose to be use for interface delegation of already scoped classes.
  */
fun AutoClose(): AutoClose =
  object : AutoClose {
    private val finalizers: Atomic<List<() -> Unit>> = Atomic(emptyList())

    fun <A : AutoCloseable> autoClose(autoCloseable: A): A {
      finalizers.update { prev -> prev + autoCloseable::close }
      return autoCloseable
    }

    fun close() {
      finalizers.get().fold<() -> Unit, Throwable?>(null) { acc, function ->
        acc.add(runCatching { function.invoke() }.exceptionOrNull())
      }?.let { throw it }
    }
  }

private fun Throwable?.add(other: Throwable?): Throwable? =
  this?.apply {
    other?.let { addSuppressed(it) }
  } ?: other