Merge pull request #32 from andreas-roehler/master

#31, solution2.1.7.8 provided

chapter02/worksheets/solution2.1.7.8.scala

@@ -0,0 +1,29 @@
+/** author: Andreas Röhler */
+/** author: Sergei Winitzki */
+
+/** 
+  Exercise 2.1.7.7
+
+  Given p:Seq[String] and q:Seq[Int] of equal length and assuming that
+  values in q do not repeat, compute a Map[Int, String] mapping numbers
+  from q to the corresponding strings from p.
+  */
+
+/** 
+  Exercise 2.1.7.8
+  Write the solution of Exercise 2.1.7.7 as a function with
+ type parameters P and Q instead of the fixed types Int and String. 
+
+  The return type of the function should be Map[P, Q]. Run some tests
+ using types P = Double and Q = Set[Boolean]. */
+
+def myMapping[P,Q](p: Seq[P], q: Seq[Q]): Map[P, Q] = {
+  val erg: Map[P, Q] = p.zip(q).toMap
+  erg
+  }
+
+val result = myMapping(Seq( Set(true), Set(true, false), Set() ), Seq( 1.0, 2.0, 3.0))
+
+val expected: Map[Set[Boolean],Double] = Map(Set(true) -> 1.0, Set(true, false) -> 2.0, Set() -> 3.0)
+
+assert(result == expected)