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/* 1) Domain entities: Bank and Account */
typealias Amount = BigDecimal
​
data class Bank(val accounts: MutableMap<String, Account> = HashMap())
​
data class Account(val id: String, val name: String) {
    var balance: Amount by TxDelegate(initialValue = Amount.ZERO) { 
        // triggers rollback on validation failure
        it >= Amount.ZERO 
    }

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interface Command { fun applyTo(system: Any) }

interface Query { fun extractFrom(system: Any): Any?}

interface EventSourcing {
    fun append(event: Any)
    fun <E> replay(eventConsumer: (E) -> Unit)
}

interface TxManager {

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val bank1 = Bank()
val memimg1 = MemImg(bank1, eventSourcing)
​
memimg1.execute(CreateAccount("janet", "Janet Doe"))
assertEquals(Amount.ZERO, bank1.accounts["janet"]!!.balance)
​
memimg1.execute(Deposit("janet", Amount(100)))
assertEquals(Amount(100), bank1.accounts["janet"]!!.balance)
​
memimg1.execute(Withdrawal("janet", Amount(10)))

xrrocha

// Skeletal Kotlin TL;DR for the truly impatient:
class MemoryImageProcessor(private val system: Any, 
                           private val eventSourcing: EventSourcing) {
    init {
        synchronized(this) {
            eventSourcing.replay<Command> { command -> command.applyTo(system) }
        }
    }

    fun execute(command: Command): Unit = synchronized(this) {

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import java.io.*;
import java.util.*;
import java.util.regex.*;
import java.util.stream.*;

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val reader = File(filename).reader()

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do {
  // ... shuffling stuff...
  // Ensure shuffling took place!
} while (range.all {
    result[it] == text[it] })

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// Java
do {
  // ... shuffling stuff...
  // Ensure shuffling took place!
  } while(IntStream.range(start, end)
      .allMatch(i ->
        result[i] == text.charAt(i)
  }));

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// Shuffle inner letter array
for (i in range) {
  // Choose a random index in region
  val rndIdx: Int = range.random()
  // Swap current/random chars
  result[rndIdx] = result[i].also {
    result[i] = result[rndIdx]
  }
}

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// Shuffle inner letter array
for (var i = start; i < end; i++) {
  // Choose a random index in region
  final var rndIdx =
    start + random.nextInt(length);
  // Swap current/random chars
  final var save = result[rndIdx];
  result[rndIdx] = result[i];
  result[i] = save;
}