I think for now this shouldn't be needed (although we'll need to modify the ScriptOptions in CSharpKernel). Like PocketView and the display helper, it should be available by default.

In that case things will work in c# out of the box and not for fsharp unless we explicitly add that dependency for f# as well. Do we need a list of references "somewhere" and those should be added to both f# and c# by default ?

@brettfo Thoughts?

You should use the same StringBuilder overloads as you have above - (string, start, length), and not create a span and call ToString on it, since that creates and copies unnecessary memory.

Even simpler is to pass in the TextWriter from the Formatter.Register call on line 15 and write to it directly. No StringBuilder needed.

Even better. In that case, I'd suggest making this project target netcoreapp2.1 or higher (or netstandard2.1), and then take advantage of the new ReadOnlySpan overload - https://docs.microsoft.com/en-us/dotnet/api/system.io.textwriter.write?view=netcore-2.1#System_IO_TextWriter_Write_System_ReadOnlySpan_System_Char__.

I'm sure it won't make a dramatic different performance wise, but why make the computer do unnecessary work when it doesn't have to.

Instead of parsing strings, I have modified the code to use the HTMLAgilityPack

Extra blank line

Weird indenting