Add all the A tasks

Task/Associative-array-Creation/Scala/associative-array-creation-1.scala

@@ -0,0 +1,6 @@
+// immutable maps
+var map = Map(1 -> 2, 3 -> 4, 5 -> 6)
+map(3) // 4
+map = map + (44 -> 99) // maps are immutable, so we have to assign the result of adding elements
+map.isDefinedAt(33) // false
+map.isDefinedAt(44) // true

Task/Associative-array-Creation/Scala/associative-array-creation-2.scala

@@ -0,0 +1,10 @@
+// mutable maps (HashSets)
+import scala.collection.mutable.HashMap
+val hash = new HashMap[int, int]
+hash(1) = 2
+hash += (1 -> 2)  // same as hash(1) = 2
+hash += (3 -> 4, 5 -> 6, 44 -> 99)
+hash(44) // 99
+hash.contains(33) // false
+hash.isDefinedAt(33) // same as contains
+hash.contains(44) // true

Task/Associative-array-Creation/Scala/associative-array-creation-3.scala

@@ -0,0 +1,4 @@
+// iterate over key/value
+hash.foreach {e => println("key "+e._1+" value "+e._2)} // e is a 2 element Tuple
+// same with for syntax
+for((k,v) <- hash) println("key " + k + " value " + v)

Task/Associative-array-Creation/Scala/associative-array-creation-4.scala

@@ -0,0 +1,4 @@
+// items in map where the key is greater than 3
+map.filter {k => k._1 > 3} //  Map(5 -> 6, 44 -> 99)
+// same with for syntax
+for((k, v) <- map; if k > 3) yield (k,v)