-----------------------------------------------------------------------------
-- |
-- Module      :  Data.Ring
-- Copyright   :  (c) 2020-2021 EMQ Technologies Co., Ltd.
-- License     :  BSD-style (see the LICENSE file)
--
-- Maintainer  :  Feng Lee, feng@emqx.io
--                Yang M, yangm@emqx.io
-- Stability   :  experimental
-- Portability :  portable
--
-- The Ring typeclass.
--
-----------------------------------------------------------------------------
module Data.Ring where

import Data.Semiring (class Semiring, zero)
import Data.Ord (class Ord, (>=))

class Semiring a => Ring a where
  sub :: a -> a -> a

infixl 6 sub as -

instance Ring Integer where
  sub = intSub

instance Ring Float where
  sub = floatSub

class Ring a => Division a where
  div :: a -> a -> a

infixl 7 div as /

instance Division Integer where
  div = intDiv

instance Division Float where
  div = floatDiv

rem :: Integer -> Integer -> Integer
rem = intRem

infixl 7 rem as %

abs :: forall a. Ord a => Ring a => a -> a
abs x = if x >= zero then x else negate x

foreign import intSub :: Integer -> Integer -> Integer
foreign import floatSub :: Float -> Float -> Float
foreign import intDiv :: Integer -> Integer -> Integer
foreign import floatDiv :: Float -> Float -> Float
foreign import intRem :: Integer -> Integer -> Integer

negate :: forall a. Ring a => a -> a
negate a = zero - a