Power Query/M interop with C#

Hey v-jingzhang, sorry, maybe I should have been more clear. My questions is actually kind of two questions in one:
1. Can M interop with C#?
For example, can I do something like either of the following:

MyCustomFunction = CSharp.Interop.GetFunction("MyCustomFunction")
Source = MyCustomFunction(...)  // Calls C# code under the hood

 or 

using MyCustomCSharpFunctions;   // Some external library e.g. a nuget package
shared CSharp.DataSource1 = () => MyCustomCSharpFunctions.GetDataSource1();   // Calls C# code under the hood

2. If this is not possible, does M have the ability to deserialise custom data types?

From your answer above it seems like the answer to this is no. Formats like arrow cannot be parsed in M yet?