T17021.hs:18:5: error:
    • The argument ‘42’ of ‘MkT’
      does not have a fixed runtime representation.
      Its kind is:
        TYPE (Id LiftedRep)
      (Use -fprint-explicit-coercions to see the full type.)
    • In the expression: MkT 42
      In an equation for ‘f’: f = MkT 42