如何使用Chart.js制作甜甜圈图的单独扇区？

Question

你能帮我吗？我必须做一个甜甜圈图，我不知道如何制作紫罗兰色的Screenshot

Prelude> ::l tree.hs
[1 of 1] Compiling Main             ( tree.hs, interpreted )

tree.hs:3:32: error:
    • Couldn't match expected type ‘Tree a -> t0 a’
                  with actual type ‘[b0]’
    • The function ‘map’ is applied to three arguments,
      but its type ‘(Tree b0 -> b0) -> [Tree b0] -> [b0]’ has only two
      In the first argument of ‘sum’, namely ‘(map (sumTree) branch (x))’
      In the second argument of ‘(+)’, namely
        ‘(sum (map (sumTree) branch (x)))’
    • Relevant bindings include
        x :: Tree a (bound at tree.hs:3:9)
        sumTree :: Tree a -> a (bound at tree.hs:3:1)
  |
3 | sumTree x = element(x) + (sum (map (sumTree) branch(x)))
  |                                ^^^^^^^^^^^^^^^^^^^^^^^

tree.hs:3:46: error:
    • Couldn't match expected type ‘[Tree b0]’
                  with actual type ‘Tree a0 -> [Tree a0]’
    • Probable cause: ‘branch’ is applied to too few arguments
      In the second argument of ‘map’, namely ‘branch’
      In the first argument of ‘sum’, namely ‘(map (sumTree) branch (x))’
      In the second argument of ‘(+)’, namely
        ‘(sum (map (sumTree) branch (x)))’
  |
3 | sumTree x = element(x) + (sum (map (sumTree) branch(x)))
  |                                              ^^^^^^

jsfiddle