
<interactive>:11:1:
    No instance for (Show a1) arising from a use of ‘print’
    Cannot resolve unknown runtime type ‘a1’
    Use :print or :force to determine these types
    Relevant bindings include it :: a1 (bound at <interactive>:11:1)
    Note: there are several potential instances:
      instance Show Unary -- Defined at ../Test.hs:37:29
      instance Show a => Show (MkT2 a) -- Defined at ../Test.hs:20:12
      instance Show a => Show (MkT a) -- Defined at ../Test.hs:17:13
      ...plus 30 others
    In a stmt of an interactive GHCi command: print it