Not a kata issue.

This doesn't seem like a kata issue, because the errors are coming from your code. I don't know F#, but reading the error messages leads me to believe that you're using a different version of F# locally, hence the errors.

Not an issue, everything works correctly.

i feel like since the data is so small for these tests, that run time is not super relevant. Run time for small sets of input is not a good indicator, it is when we talk about "sufficently" large enough data sets.

Works for me