Scala : add scala/example

2 files changed, 82 insertions, 0 deletions

diff --git a/Scala/example/src/main/scala/common/package.scala b/Scala/example/src/main/scala/common/package.scala
new file mode 100644
index 0000000..f1c74c3
--- /dev/null
+++ b/Scala/example/src/main/scala/common/package.scala
@@ -0,0 +1,40 @@
+import java.io.File
+
+package object common {
+
+  /** An alias for the `Nothing` type.
+   *  Denotes that the type should be filled in.
+   */
+  type ??? = Nothing
+
+  /** An alias for the `Any` type.
+   *  Denotes that the type should be filled in.
+   */
+  type *** = Any
+
+  
+  /**
+   * Get a child of a file. For example,
+   * 
+   *   subFile(homeDir, "b", "c")
+   * 
+   * corresponds to ~/b/c
+   */
+  def subFile(file: File, children: String*) = {
+    children.foldLeft(file)((file, child) => new File(file, child))
+  }
+
+  /**
+   * Get a resource from the `src/main/resources` directory. Eclipse does not copy
+   * resources to the output directory, then the class loader cannot find them.
+   */
+  def resourceAsStreamFromSrc(resourcePath: List[String]): Option[java.io.InputStream] = {
+    val classesDir = new File(getClass.getResource(".").toURI)
+    val projectDir = classesDir.getParentFile.getParentFile.getParentFile.getParentFile
+    val resourceFile = subFile(projectDir, ("src" :: "main" :: "resources" :: resourcePath): _*)
+    if (resourceFile.exists)
+      Some(new java.io.FileInputStream(resourceFile))
+    else
+      None
+  }
+}
diff --git a/Scala/example/src/main/scala/example/Lists.scala b/Scala/example/src/main/scala/example/Lists.scala
new file mode 100644
index 0000000..4e5feee
--- /dev/null
+++ b/Scala/example/src/main/scala/example/Lists.scala
@@ -0,0 +1,42 @@
+package example
+
+import common._
+
+object Lists {
+  /**
+   * This method computes the sum of all elements in the list xs. There are
+   * multiple techniques that can be used for implementing this method, and
+   * you will learn during the class.
+   *
+   * For this example assignment you can use the following methods in class
+   * `List`:
+   *
+   *  - `xs.isEmpty: Boolean` returns `true` if the list `xs` is empty
+   *  - `xs.head: Int` returns the head element of the list `xs`. If the list
+   *    is empty an exception is thrown
+   *  - `xs.tail: List[Int]` returns the tail of the list `xs`, i.e. the the
+   *    list `xs` without its `head` element
+   *
+   *  ''Hint:'' instead of writing a `for` or `while` loop, think of a recursive
+   *  solution.
+   *
+   * @param xs A list of natural numbers
+   * @return The sum of all elements in `xs`
+   */
+  def sum(xs: List[Int]): Int = ???
+
+  /**
+   * This method returns the largest element in a list of integers. If the
+   * list `xs` is empty it throws a `java.util.NoSuchElementException`.
+   *
+   * You can use the same methods of the class `List` as mentioned above.
+   *
+   * ''Hint:'' Again, think of a recursive solution instead of using looping
+   * constructs. You might need to define an auxiliary method.
+   *
+   * @param xs A list of natural numbers
+   * @return The largest element in `xs`
+   * @throws java.util.NoSuchElementException if `xs` is an empty list
+   */
+  def max(xs: List[Int]): Int = ???
+}