local.fs

    let rec takeFreshConsTail cons n l =
        match l with
        | [] -> 
            if n <> 0 then failwith "insufficient length"
            setFreshConsTail cons []
        | x::xs ->
            if n > 0 then
                let cons2 = freshConsNoTail x
                setFreshConsTail cons cons2
                takeFreshConsTail cons2 (n - 1) xs
            else
                setFreshConsTail cons []

    let take n l =
        if n < 0 then failwith "negative count"
        if n = 0 then []
        else 
        match l with
        | [] -> failwith "insufficient length"
        | [x] -> if n = 1 then l else failwith "insufficient length"
        | x::xs ->
            let cons = freshConsNoTail x
            takeFreshConsTail cons (n - 1) xs
            cons