addExprP :: Parser E.Expr
addExprP = 
    do
        lhs <- constInt
        token $ literal "+"
        rhs <- constInt
        return $ lhs E.:+: rhs
addExprP :: Parser E.Expr
addExprP = 
    do
        lhs <- constInt
        token $ literal "+"
        rhs <- constInt
        return $ lhs E.:+: rhs
addExprP = 
    do
        lhs <- constInt
        token $ literal "+"
        rhs <- constInt
        return $ lhs E.:+: rhs