andrewharmellaw

koan("Tuples can be created easily") {
  val tuple = ("apple", "dog")
  tuple should be(Tuple2("apple", "dog")) 
} 

andrewharmellaw

koan("Tuples can be created easily") {
    val tuple = ("apple", "dog")
    tuple should be("apple", "dog")
}

andrewharmellaw

val b = a.filterNot(v => v == 5) // remove where value is 5

andrewharmellaw

// map a function to double the numbers over the list
a.map {v => v * 2} should equal(List(__, __, __, __, __)) 

andrewharmellaw

koan("Lists can be 'reduced' with a mathematical operation") {
  val a = List(1, 3, 5, 7)
  // note the two _s below indicate the first and second args respectively
  a.reduceLeft(_ + _) should equal(16)      // 1 + 3 + 5 + 7
  a.reduceLeft(_ * _) should equal(105)     // 1 * 3 * 5 * 7
} 

andrewharmellaw

koan("Foldleft is like reduce, but with an explicit starting value") {
  val a = List(1, 3, 5, 7)
  // NOTE: foldLeft uses a form called currying that we will explore later
  a.foldLeft(0)(_ + _) should equal(16)
  a.foldLeft(10)(_ + _) should equal(26)
  a.foldLeft(1)(_ * _) should equal(105)
  a.foldLeft(0)(_ * _) should equal(0)
} 

andrewharmellaw

val a = (1 to 5).toList

andrewharmellaw

koan("Lists reuse their tails") {
  val d = Nil
  val c = 3 :: d
  val b = 2 :: c
  val a = 1 :: b 

  a should be(List(1, 2, 3))
  a.tail should be(b)
  b.tail should be(c)
  c.tail should be(d)

andrewharmellaw

// NOTE that the following will not compile, as iterators do not implement "contains"
// mapValues.contains("Illinois") should be (true) 

andrewharmellaw

scala> val myMap = Map("MI" -> "Michigan", "OH" -> "Ohio", "WI" -> "Wisconsin", "MI" -> "Michigan")
myMap: scala.collection.immutable.Map[java.lang.String,java.lang.String] = Map(MI -> Michigan, OH -> Ohio, WI -> Wisconsin) 

scala> val mapValues = myMap.values
mapValues: Iterable[java.lang.String] = MapLike(Michigan, Ohio, Wisconsin)