mc19.hs:10:31: error:
    • Occurs check: cannot construct the infinite type: a ~ [a]
      Expected type: [a] -> [a]
        Actual type: [a] -> [[a]]
    • In the expression: inits
      In a stmt of a monad comprehension: then inits
      In the expression: [x | x <- [3, 2, 1], then inits]