try catch cause

infix fun <T, E : Exception> Any.tryForCause(init: () -> T): TryForCause<T, E> {
  return TryForCause<T, E>().execute(init)
}

class TryForCause<T, out E : Exception> {
  private var throwable: Exception? = null
  private var result: Any? = null
  fun execute(init: () -> T): TryForCause<T, E> {
    try {
      result = init()
    } catch (e: Exception) {
      throwable = e
    }
    return this
  }

  @Suppress("UNCHECKED_CAST")
  infix fun catchCause(init: (E) -> T): T {
    val ex = throwable
    if (ex != null && ex.cause.checkCastable<E>()) {
      return init(ex.cause as E)
    }
    ex?.run { throw ex }
    return result as T
  }

  private fun <T : Any> Any?.checkCastable(): Boolean {
    return try {
      @Suppress("UNCHECKED_CAST")
      this as T
      true
    } catch (e: Exception) {
      println(e.message)
      false
    }
  }
}