Showing different runtime values

readme.md

 dotnet run -f net8.0
Hello from F#
IFDEF: This is .NET 8.0
Assembly: .NETCoreApp,Version=v8.0
System DLL: 8.0.0.0

After setting RollForward

Hello from F#
IFDEF: This is .NET 8.0
Assembly: .NETCoreApp,Version=v8.0
System DLL: 10.0.0.0

different-tfms.fsproj

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFrameworks>net8.0;net9.0;net10.0</TargetFrameworks>
    <RootNamespace>different_tfms</RootNamespace>
  </PropertyGroup>

  <ItemGroup>
    <Compile Include="Program.fs" />
  </ItemGroup>

</Project>

DifferentTFMsAndRuntimeAssemblies.fs

let ifDefRuntime =
#if NET8_0
        "This is .NET 8.0"
#endif
#if NET9_0
        "This is .NET 9.0"
        
#endif
#if NET10_0
        "This is .NET 10.0"
#endif

let assemblyRuntime =
    System.Reflection.Assembly
        .GetExecutingAssembly()
        .GetCustomAttributes(typeof<System.Runtime.Versioning.TargetFrameworkAttribute>, false)
    |> Seq.cast<System.Runtime.Versioning.TargetFrameworkAttribute>
    |> Seq.head
    |> fun attr -> attr.FrameworkName

let systemDllVersion =
    typeof<System.String>
        .Assembly
        .GetName()
        .Version
    |> string

// For more information see https://aka.ms/fsharp-console-apps
printfn $"Hello from F#"
printfn $"IFDEF: {ifDefRuntime}"
printfn $"Assembly: {assemblyRuntime}"
printfn $"System DLL: {systemDllVersion}"