module _35

open common

let circularPrime =
    let rotations (s:string) =
        let len = s.Length
        seq {
            for n in 0..(len - 1) do
                yield s.Substring(len - n)
                      + s.Substring(0, len - n)
        } |> Seq.toList

    let oddOr2 i = i % 2 = 1 || i = 2
        
    let pa = 
        primeArray 1000000 
        |> Array.filter (numDigits >> (Array.forall oddOr2))
        |> Array.map (string)
       
    let isPrime = isPrimeFunByArray pa
    pa
    |> Array.map rotations
    |> Array.filter (List.forall isPrime)
    |> Array.map (Seq.nth 0)
    |> Array.length