-- TODO: make interpolation possible
toLatex (Op op a b) =
    case op of
      "*" -> toLatex a ++ "\\cdot" ++ toLatex b
      "/" -> "\\frac" ++ group (toLatex a) ++ group (toLatex b)
      _   -> group (toLatex a) ++ op ++ group (toLatex b)
toLatex (Op op a b) =
    case op of
      "*" -> toLatex a ++ "\\cdot" ++ toLatex b
      "/" -> "\\frac" ++ group (toLatex a) ++ group (toLatex b)
      _   -> group (toLatex a) ++ op ++ group (toLatex b)
toLatex (Op op a b) =
    case op of
      "*" -> toLatex a ++ "\\cdot" ++ toLatex b
      "/" -> "\\frac" ++ group (toLatex a) ++ group (toLatex b)
      _   -> group (toLatex a) ++ op ++ group (toLatex b)