tcfail193.hs:10:31: error:
    • Couldn't match type ‘a’ with ‘[a]’
      Expected: [a] -> [a]
        Actual: [a] -> [[a]]
      ‘a’ is a rigid type variable bound by
        a type expected by the context:
          forall {a}. [a] -> [a]
        at tcfail193.hs:10:31-35
    • In the expression: inits
      In a stmt of a list comprehension: then inits
      In the expression: [x | x <- [3, 2, 1], then inits]