opPrec, opLeftPrec, opRightPrec :: ArithOp ty -> Prec
opPrec      (precInfo -> (x, _, _)) = x
opPrec, opLeftPrec, opRightPrec :: ArithOp ty -> Prec
opPrec      (precInfo -> (x, _, _)) = x
opPrec      (precInfo -> (x, _, _)) = x