xrrocha

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

/* 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 
    }

xrrocha

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 {

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) {

xrrocha

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

xrrocha

package wscrambler

object WordScrambler {
  private val WORD_REGEX =
    """\p{IsLatin}(\p{IsLatin})\1*(?!\1)\p{IsLatin}\p{IsLatin}+""".toRegex()

  @JvmStatic // JVM static method
  // CLI FQN: wscrambler.Scrambler
  fun main(args: Array<String>) {

xrrocha

// Nullable constructor arg w/default
class Numberer(pattern: String? = null) {

  companion object {
    // Public constant
    const val DEF_PATTERN = "000,000"
  }

  // Private field w/fallback value (?:)

xrrocha

package wscrambler

object WordScrambler {
  // Regex compiled only once:
  // at object initialization.
  // Inaccessible to others,
  // even in the same package.
  private val WORD_REGEX =
    """\p{IsLatin}(\p{IsLatin})\1*(?!\1)\p{IsLatin}\p{IsLatin}+"""

xrrocha

wscrambler.scrambleWords("Hey there!")

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// Scramble from files/stdin to stdout
fun main(args: Array<String>) {

  // Collect readers from args/stdin
  val readers =
    if (args.isNotEmpty())
      args.map { File(it).reader() }
    else
      // in: quoted because reserved