I'm not familiar with F#, but I do hate CSV tools that try type inference on data; in my opinion the csvkit tools should have the -I option on by default.
The thing is, I've used .NET a lot, and C# and F# I can code in my sleep. The same object system, integrated in PowerShell, makes it really hard to use.
I think F#-interactive (FSI) with its Hindley-Milner type-inference, would have been a much better base for a shell.