showTerm (TupleTerm ts) =
  "{" ++ intercalate ", " (map showTerm ts) ++ "}"
showTerm (TupleTerm ts) =
  "{" ++ intercalate ", " (map showTerm ts) ++ "}"
showTerm (TupleTerm ts) =
  "{" ++ intercalate ", " (map showTerm ts) ++ "}"