diff options
Diffstat (limited to 'Scala/example/src/main/scala')
-rw-r--r-- | Scala/example/src/main/scala/common/package.scala | 40 | ||||
-rw-r--r-- | Scala/example/src/main/scala/example/Lists.scala | 42 |
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 = ??? +} |