Merge pull request #46 from jonboiser/patch-3

Extractors chapter - markdown fixes

Author: Alejandro Gómez

src/main/scala/stdlib/Extractors.scala

@@ -11,7 +11,7 @@ object Extractors extends FlatSpec with Matchers with org.scalaexercises.definit
     *
     * For instance, the following code defines an extractor object `Twice`.
     *
-    *
+    * {{{
     * object Twice {
     * def apply(x: Int): Int = x * 2
     * def unapply(z: Int): Option[Int] = if (z%2 == 0) Some(z/2) else None
@@ -21,26 +21,26 @@ object Extractors extends FlatSpec with Matchers with org.scalaexercises.definit
     * val x = Twice(21)
     * x match { case Twice(n) => Console.println(n) } // prints 21
     * }
-    *
+    * }}}
     *
     * There are two syntactic conventions at work here:
     *
-    * * The pattern `case Twice(n)` will cause an invocation of `Twice.unapply`, which is used to match even number; the return value of the `unapply` signals whether the argument has matched or not, and any sub-values that can be used for further matching. Here, the sub-value is `z/2`
-    * * The `apply` method is not necessary for pattern matching. It is only used to mimick a constructor. `val x = Twice(21)` expands to `val x = Twice.apply(21)`.
+    * - The pattern `case Twice(n)` will cause an invocation of `Twice.unapply`, which is used to match even number; the return value of the `unapply` signals whether the argument has matched or not, and any sub-values that can be used for further matching. Here, the sub-value is `z/2`
+    * - The `apply` method is not necessary for pattern matching. It is only used to mimick a constructor. `val x = Twice(21)` expands to `val x = Twice.apply(21)`.
     *
     * The code in the preceding example would be expanded as follows:
     *
-    *
+    * {{{
     * object TwiceTest extends Application {
     * val x = Twice.apply(21)
     * Twice.unapply(x) match { case Some(n) => Console.println(n) } // prints 21
     * }
-    *
+    * }}}
     * The return type of an `unapply` should be chosen as follows:
     *
-    * * If it is just a test, return a `Boolean`. For instance `case even()`
-    * * If it returns a single sub-value of type `T`, return a `Option[T]`
-    * * If you want to return several sub-values `T1,...,Tn`, group them in an optional tuple `Option[(T1,...,Tn)]`.
+    * - If it is just a test, return a `Boolean`. For instance `case even()`
+    * - If it returns a single sub-value of type `T`, return a `Option[T]`
+    * - If you want to return several sub-values `T1,...,Tn`, group them in an optional tuple `Option[(T1,...,Tn)]`.
     *
     * Sometimes, the number of sub-values is fixed and we would like to return a sequence. For this reason, you can also define patterns through `unapplySeq`. The last sub-value type `Tn` has to be `Seq[S]`. This mechanism is used for instance in pattern `case List(x1, ..., xn)`.
     *