tcfail042.hs:15:10: error: [GHC-39999]
    • Could not deduce ‘Num a’
        arising from the superclasses of an instance declaration
      from the context: (Eq a, Show a)
        bound by the instance declaration at tcfail042.hs:15:10-34
      Possible fix:
        add (Num a) to the context of the instance declaration
    • In the instance declaration for ‘Bar [a]’

tcfail042.hs:17:18: error: [GHC-39999]
    • Could not deduce ‘Num a’ arising from a use of ‘foo’
      from the context: (Eq a, Show a)
        bound by the instance declaration at tcfail042.hs:15:10-34
      Possible fix:
        add (Num a) to the context of the instance declaration
    • In the expression: foo xs
      In an equation for ‘bar’:
          bar (x : xs)
            = foo xs
            where
                u = x == x
                v = show x
      In the instance declaration for ‘Bar [a]’