C# 8.0 Preview: First four feature

 Recently in channel 9, Mads Torgersen demonstrated the first few features for C# 8. Below are the few features.

• Nullable Reference Types

With C# 8.0, references type would not be nullable by default. Assigning null to a non-nullable reference type will be a compiler warning, similarly reading from a nullable type would be a compiler warning unless the variable in question was explicitly checked for null ahead of time.

• Async Streams

Async streams are the asynchronous equivalent of IEnumerable. Syntax for the same is

• Default Interface

A default interfaces programming capability, so interfaces can be evolve via virtual extension methods. An API author could add methods to an interface in future versions without breaking source or binary compatibility. The feature already is available in languages such as Java.

• Extension Everything

Long-time pending feature was extension properties. Under the new design, there is a new top-level construct called an extension. Example if you want to create extension methods and properties for an Employee class you can write:

For more information you can refer C# Language Design Repo.