Add result example as long-term goal.

examples/result.dm

@@ -0,0 +1,26 @@
+enum Result<T, E>
+    Ok(T),
+    Err(E)
+end
+
+int Error
+    message: String
+end
+
+class BadArgumentError(argument: String) : Error
+    pub message = "Invalid argument: ${argument}"
+end
+
+fn main(args: Array<String>) -> Result<Int, Error>
+    let left = args.get(0).flatMap(Int::parse)
+    if left is None then
+        return Err(BadArgumentError(args.get(0)))
+    end
+
+    let right = args.get(1).flatMap(Int::parse)
+    if right is None then
+        return Err(BadArgumentError(args.get(1)))
+    end
+
+    Ok(left.unwrap() + right.unwrap())
+end