New F# Bowling game

After a bit of feedback from a number of sources and addressing some of my concerns with the duplication

let rec score_bowls bowls =

let rec score_bowls' frame l =

let sum b = (List.fold_right (fun x y -> x + y) b 0)

let nextframe = score_bowls' (frame+1)

match l with

| _ when frame = 10 -> sum l

| [10;s] -> 10 + s + s

| 10 :: s :: n :: tail -> 10 + s + n + nextframe (s :: n :: tail )

| f :: s :: n :: tail -> f + s + (if((f+s)=10) then n else 0) + nextframe (n :: tail)

| _ -> sum l

score_bowls' 1 bowls