oxbowlakes

trait Monoid[A] {
  def identity: A
  def mplus(a1: A, a2: A): A
}

object Monoid {
  implicit val IntMonoid = new Monoid[Int] {
    def identity = 0
    def mplus(a1: Int, a2: Int) = a1 + a2
  }

oxbowlakes

object Positions {
  trait Investment
  trait Position {
    def investment: Investment
    def tradingPnL: Option[Double]
    def inventoryPnL: Option[Double]
    final def totalPnL = inventoryPnL → tradingPnL
  }

  import Monoid._

oxbowlakes

object TradingDays extends App {

  import scalaz._
  import Scalaz._

  case class Trade(sym: String, trader: String, qty: Int)

  case class TradingDay(symbols: Map[String, SymDay] = Map.empty)

  object TradingDay {

oxbowlakes

This is how we create an inclusive/exclusive range of Ints:

  val ie = 0 until 500

//1. Fill in the missing item to create a range of Ints from 1 to 100 inclusive

  val ints = 1 ??? 100

//2. Find the sum of the integers in this range

oxbowlakes

// The declaration of a value in scala looks like this:

    val x = 1
//  ^   ^   ^
//  ^   ^   the value we wish to assign our new value to
//  ^   identifier (ie name of value)
//  type of value (val or var)

// Each identifier in scala has an associated type (or, more accurately, it has many types ranging from the least to the most specific)

oxbowlakes

// In scala a def (called a "method") is defined as follows:

    def foo(arg: String): Int = expr
//  ^   ^  ^^    ^        ^     ^
//  ^   ^  ^^    ^        ^     an expression, whose type must match the declared return type, if specified
//  ^   ^  ^^    ^        ^     
//  ^   ^  ^^    ^        the declared return type (optional).
//  ^   ^  ^^    ^        
//  ^   ^  ^^    the type of each argument must be declared
//  ^   ^  ^^

oxbowlakes

import scalaz._;import Scalaz._; import concurrent._

/* Imagine you have some expensive calculations you wish to make: */
trait RawApi {
  def expensiveInt: Int = Int.MaxValue
  def expensiveString: String = "expensive"
}

/* You wish to write a program using this API */
case class Result(i: Int, s: String)

oxbowlakes

<?xml version="1.0" encoding="UTF-8"?>
<scheme name="OxbowSolarizedDark2" version="124" parent_scheme="Default">
  <option name="LINE_SPACING" value="1.2" />
  <option name="EDITOR_FONT_SIZE" value="13" />
  <option name="EDITOR_FONT_NAME" value="Consolas" />
  <colors>
    <option name="ADDED_LINES_COLOR" value="" />
    <option name="ANNOTATIONS_COLOR" value="2b36" />
    <option name="ANNOTATIONS_MERGED_COLOR" value="" />
    <option name="CARET_COLOR" value="dc322f" />

oxbowlakes

///////////////////////////////////////////////////////////////////////
// You are supplied with the following interfaces/implementations
///////////////////////////////////////////////////////////////////////

/** Interface representing the performing of a computation at some specific key */
public interface Computation<K, V> {
  K key();
  V compute();
}

oxbowlakes

import java.math.BigInteger

/**
 * Clients can use this class instead, which means they only need fill in the 
 * V compute(K) method
 */ 
abstract class ConcCache2<K, V> {
  
  private final ConcCache<K, V> cache = new ConcCache<>();