Elmish.WPF config file problems in Visual Studio 2019 on Win10

Question

As a C# developer my solution (*.sln) and project (*.csproj) configuration files are rarely a problem and Visual Studio (VS) manages things well. Result is I am largely unaware of this essential plumbing.

But now learning F# and Elmish.WPF I discover VS has problems with my configuration.

I have forked Elmish.WPF here: https://bitbucket.org/fandco/elmish.wpf/src/master/ and my questions pertain to two (2) branches of this repository built and run in Visual Studio 2019 v16.9.4, .NET Framework v4.8.04084, in Win10 (v 21H1).

That fork of Elmish.WPF has all my .NET configuration ignorance in full view. ;-)

Branch master is untouched and C# project SingleCounter is the startup project and it runs.

Relevant here are HEAD of branches:

• RestoringFandCoExperiments - config error in ../src/Samples/Ztest/MainWindow.xaml
• Ztest_and_ZtestDotCore_works - runs ../src/Samples/Ztest just fine.

The error in branch RestoringFandCoExperiments with Ztest (C# project calling the F# Elmish.WPF project) in MainWindows.xaml is ….

QUESTIONS:

1. Why cannot I include the F# project Simple.Core into a C# project Ztest as I attempt to do in branch RestoringFandCoExperiments (see picture above)?

2. Why must Ztest and Ztest.Core share the same name prefix (Ztest) even though they are separate projects?

3. Perhaps this comes down to my not understanding something fundamental about CLR namespaces and how to specify them when connecting C# and F# projects?

Thanks!