I downloaded a demo by Jon Skeet called 'PclPal' as found here - it refuses to compile in Visual Studio 2013 due to some C# syntax I don't recognise.
Two of the .cs files appear to have constructor logic in the actually class declarations, like so:
public class Profile(string path, IEnumerable<SupportedRuntime> runtimes)
{
public string Name { get; } = System.IO.Path.GetFileName(path);
public String Path { get; } = path;
public IReadOnlyCollection<SupportedRuntime> SupportedRuntimes { get; } = runtimes.ToList().AsReadOnly();
What is this? Is this some future version of C# I've not yet learned?
EDIT: I don't see this as a duplicate question. The linked question says 'Why don't primary constructors compile?', whereas this question effectively says 'What are [these things that turn out to be] primary constructors?'