We can use a similar approach to accumlate the intermediate bowling
scores for a possibly incomplete sequence of valid throws - update the
sequence after each throw and recalculate the scores.

Start = scores [10, 4,6, 10, 4,6, 10, 4,6, 10, 4,6] [] 0 0

scores pins a total 10    = a  
scores []   a total count = a
scores [x]  a total count = a

scores [x,y] a total count
   | x == 10   = a
   | x+y == 10 = a
   | otherwise = a++[total+x+y]

scores [x,y,z:rest] a total count
   | x == 10   = scores [y,z:rest] (a++[total+x+y+z]) (total+x+y+z)
(count+1)
   | x+y == 10 = scores   [z:rest] (a++[total+x+y+z]) (total+x+y+z)
(count+1)
   | otherwise = scores   [z:rest] (a++[total+x+y])   (total+x+y)  
(count+1)

The answer in this case would be [20,40,60,80,100,120,140] - the 8th
total for the spare cannot be calculated until the next throw.

best wishes, Isaac