C# 6.0 new features in a fairly simple C# file.

Cs60NewFeatures.cs

// C#6 feature: Auto-property Initializer
public Guid Id { get; private set; } = Guid.NewGuid();

// C#6 feature: Auto-property Initializer (Getter only)
public Guid Id { get; } = Guid.NewGuid();

// C#6 feature: String Interpolation
string test = $"{this.FirstName} {this.LastName} ({this.Id})";
FormattableString test2 = $"{this.FirstName} {this.LastName} ({this.Id})";
Console.WriteLine(test2.ArgumentCount + " " + test2.Format);

// C#6 feature: Using Static
using static System.Console;
class Program
{
  static void Main()
  {
    WriteLine("LungButter");
  }
}

// C#6 feature: Expression Bodied Member (property)
public string FullName
{
  get
  {
    return $"{this.FirstName} {this.LastName}";
  }
}
// ...can now be...
public string FullName => $"{this.FirstName} {this.LastName}";
// This only works for one liners!

// C#6 feature: Expression Bodied Member (void method)
public void Echo(string message) => Console.WriteLine($"This message is: {message}");
// This only works for one liners!

// C#6 feature: Expression Bodied Member (method that returns)
public string Yell(string message) => message.ToUpper();
// This only works for one liners!

// C#6 feature: Dictionary Initializer
var contacts = new Dictionary<int, Contact>
{
  [1] = new Contact { FirstName = "Justin", LastName = "Aurand" },
  [2] = new Contact { FirstName = "Jerk", LastName = "Face" }
};

// C#6 features: Add Extension (for collection initiatlizer)
public static Contact Add(this ContactsCollection list, Contact contact)
{
  return list.Insert(contact);
}
// Now you can use inline initialization for your ContactsCollection class!

// C#6 feature: Null Conditional Access
public static bool IsMaxLengthValid(this Contact contact)
{
  var length = contact?.LastName?.Length ?? 0;
  return length <= 20;
}

// C#6 feature: nameof Operator
public static string GetFirstName(this Contact contact)
{
  if (contact == null)
    throw new ArgumentNullException(nameof(contact));
  return contact.FirstName;
}

// C#6 feature: Await Inside Catch Block (works for finally, too!)
private static async void ReadFileAsync()
{
  var filename = "test.txt";
  try
  {
    var result = await FileUtil.ReadFileAsync(filename);
    Console.WriteLine(result);
  }
  catch (Exception)
  {
    await FileUtil.LogAsync("Unknown Error.");
  }
}

// C#6 feature: Exception Filter
private static async void ReadFileAsync()
{
  var filename = "test.txt";
  try
  {
    var result = await FileUtil.ReadFileAsync(filename);
    Console.WriteLine(result);
  }
  catch (FileNotFoundException ex) when (ex.FileName.EndsWith(".txt"))
  {
    await FileUtil.LogAsync($"File not found: {ex.FileName}");
  }
  catch (Exception)
  {
    await FileUtil.LogAsync("Unknown Error.");
  }
}

// You can download the Rosyln C# compiler as a Nuget package.
static void RoslynDemo()
{
  var code = File.ReadAllText("Person.cs");
  var tree = SyntaxFactory.ParseSyntaxTree(code);

  // Create compilation
  var options = new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary);
  var reference = MetadataReference.CreateFromFile(typeof(object).Assembly.Location);
  var compilation = CSharpCompliation.Create("test")
    .WithOptions(options)
    .AddReferences(reference)
    .AddSyntaxTrees(tree);

  // Show Diagnostics
  var diagnostics = compilation.GetDiagnostics();
  foreach (var diagnostic in diagnostics)
    Console.WriteLine(diagnostic.ToString());

  // Execute Code
  using (var stream = new MemoryStream())
  {
    compilation.Emit(stream);
    var assembly = Assembly.Load(stream.GetBuffer());
    var type = assembly.GetType("CS60Demo.Person");
    dynamic Person = Activator.CreateInstance(type);
    person.SayHello();
  }
}