{-# LANGUAGE Trustworthy #-}
{-# LANGUAGE CPP, NoImplicitPrelude, MagicHash, UnboxedTuples #-}
{-# OPTIONS_HADDOCK not-home #-}

-----------------------------------------------------------------------------
-- |
-- Module      :  GHC.Num
-- Copyright   :  (c) The University of Glasgow 1994-2002
-- License     :  see libraries/base/LICENSE
--
-- Maintainer  :  cvs-ghc@haskell.org
-- Stability   :  internal
-- Portability :  non-portable (GHC Extensions)
--
-- The 'Num' class and the 'Integer' type.
--
-----------------------------------------------------------------------------


module GHC.Num
   ( module GHC.Num
   , module GHC.Num.Integer
   , module GHC.Num.Natural
    -- reexported for backward compatibility
   , module GHC.Natural
   , module GHC.Integer
   )
where

#include "MachDeps.h"

import qualified GHC.Natural
import qualified GHC.Integer

import GHC.Base
import GHC.Num.Integer
import GHC.Num.Natural

infixl 7  *
infixl 6  +, -

default ()              -- Double isn't available yet,
                        -- and we shouldn't be using defaults anyway

-- | Basic numeric class.
--
-- The Haskell Report defines no laws for 'Num'. However, @('+')@ and @('*')@ are
-- customarily expected to define a ring and have the following properties:
--
-- [__Associativity of @('+')@__]: @(x + y) + z@ = @x + (y + z)@
-- [__Commutativity of @('+')@__]: @x + y@ = @y + x@
-- [__@'fromInteger' 0@ is the additive identity__]: @x + fromInteger 0@ = @x@
-- [__'negate' gives the additive inverse__]: @x + negate x@ = @fromInteger 0@
-- [__Associativity of @('*')@__]: @(x * y) * z@ = @x * (y * z)@
-- [__@'fromInteger' 1@ is the multiplicative identity__]:
-- @x * fromInteger 1@ = @x@ and @fromInteger 1 * x@ = @x@
-- [__Distributivity of @('*')@ with respect to @('+')@__]:
-- @a * (b + c)@ = @(a * b) + (a * c)@ and @(b + c) * a@ = @(b * a) + (c * a)@
-- [__Coherence with 'toInteger'__]: if the type also implements 'GHC.Real.Integral', then
-- 'fromInteger' is a left inverse for 'GHC.Real.toInteger', i.e. @fromInteger (toInteger i) == i@
--
-- Note that it /isn't/ customarily expected that a type instance of both 'Num'
-- and 'Ord' implement an ordered ring. Indeed, in @base@ only 'Integer' and
-- 'Data.Ratio.Rational' do.
class  Num a  where
    {-# MINIMAL (+), (*), abs, signum, fromInteger, (negate | (-)) #-}

    (+), (-), (*)       :: a -> a -> a
    -- | Unary negation.
    negate              :: a -> a
    -- | Absolute value.
    abs                 :: a -> a
    -- | Sign of a number.
    -- The functions 'abs' and 'signum' should satisfy the law:
    --
    -- > abs x * signum x == x
    --
    -- For real numbers, the 'signum' is either @-1@ (negative), @0@ (zero)
    -- or @1@ (positive).
    signum              :: a -> a
    -- | Conversion from an 'Integer'.
    -- An integer literal represents the application of the function
    -- 'fromInteger' to the appropriate value of type 'Integer',
    -- so such literals have type @('Num' a) => a@.
    fromInteger         :: Integer -> a

    {-# INLINE (-) #-}
    {-# INLINE negate #-}
    a
x - a
y               = a
x a -> a -> a
forall a. Num a => a -> a -> a
+ a -> a
forall a. Num a => a -> a
negate a
y
    negate a
x            = a
0 a -> a -> a
forall a. Num a => a -> a -> a
- a
x

-- | the same as @'flip' ('-')@.
--
-- Because @-@ is treated specially in the Haskell grammar,
-- @(-@ /e/@)@ is not a section, but an application of prefix negation.
-- However, @('subtract'@ /exp/@)@ is equivalent to the disallowed section.
{-# INLINE subtract #-}
subtract :: (Num a) => a -> a -> a
subtract :: forall a. Num a => a -> a -> a
subtract a
x a
y = a
y a -> a -> a
forall a. Num a => a -> a -> a
- a
x

-- | @since 2.01
instance Num Int where
    I# Int#
x + :: Int -> Int -> Int
+ I# Int#
y = Int# -> Int
I# (Int#
x Int# -> Int# -> Int#
+# Int#
y)
    I# Int#
x - :: Int -> Int -> Int
- I# Int#
y = Int# -> Int
I# (Int#
x Int# -> Int# -> Int#
-# Int#
y)
    negate :: Int -> Int
negate (I# Int#
x) = Int# -> Int
I# (Int# -> Int#
negateInt# Int#
x)
    I# Int#
x * :: Int -> Int -> Int
* I# Int#
y = Int# -> Int
I# (Int#
x Int# -> Int# -> Int#
*# Int#
y)
    abs :: Int -> Int
abs Int
n  = if Int
n Int -> Int -> Bool
`geInt` Int
0 then Int
n else Int -> Int
forall a. Num a => a -> a
negate Int
n

    signum :: Int -> Int
signum Int
n | Int
n Int -> Int -> Bool
`ltInt` Int
0 = Int -> Int
forall a. Num a => a -> a
negate Int
1
             | Int
n Int -> Int -> Bool
`eqInt` Int
0 = Int
0
             | Bool
otherwise   = Int
1

    fromInteger :: Integer -> Int
fromInteger Integer
i = Int# -> Int
I# (Integer -> Int#
integerToInt# Integer
i)

-- | @since 2.01
instance Num Word where
    (W# Word#
x#) + :: Word -> Word -> Word
+ (W# Word#
y#)      = Word# -> Word
W# (Word#
x# Word# -> Word# -> Word#
`plusWord#` Word#
y#)
    (W# Word#
x#) - :: Word -> Word -> Word
- (W# Word#
y#)      = Word# -> Word
W# (Word#
x# Word# -> Word# -> Word#
`minusWord#` Word#
y#)
    (W# Word#
x#) * :: Word -> Word -> Word
* (W# Word#
y#)      = Word# -> Word
W# (Word#
x# Word# -> Word# -> Word#
`timesWord#` Word#
y#)
    negate :: Word -> Word
negate (W# Word#
x#)         = Word# -> Word
W# (Int# -> Word#
int2Word# (Int# -> Int#
negateInt# (Word# -> Int#
word2Int# Word#
x#)))
    abs :: Word -> Word
abs Word
x                  = Word
x
    signum :: Word -> Word
signum Word
0               = Word
0
    signum Word
_               = Word
1
    fromInteger :: Integer -> Word
fromInteger Integer
i          = Word# -> Word
W# (Integer -> Word#
integerToWord# Integer
i)

-- | @since 2.01
instance Num Integer where
    + :: Integer -> Integer -> Integer
(+) = Integer -> Integer -> Integer
integerAdd
    (-) = Integer -> Integer -> Integer
integerSub
    * :: Integer -> Integer -> Integer
(*) = Integer -> Integer -> Integer
integerMul
    negate :: Integer -> Integer
negate         = Integer -> Integer
integerNegate
    fromInteger :: Integer -> Integer
fromInteger Integer
i  = Integer
i

    abs :: Integer -> Integer
abs    = Integer -> Integer
integerAbs
    signum :: Integer -> Integer
signum = Integer -> Integer
integerSignum

-- | Note that `Natural`'s 'Num' instance isn't a ring: no element but 0 has an
-- additive inverse. It is a semiring though.
--
-- @since 4.8.0.0
instance Num Natural where
    + :: Natural -> Natural -> Natural
(+)         = Natural -> Natural -> Natural
naturalAdd
    (-)         = Natural -> Natural -> Natural
naturalSubThrow
    * :: Natural -> Natural -> Natural
(*)         = Natural -> Natural -> Natural
naturalMul
    negate :: Natural -> Natural
negate      = Natural -> Natural
naturalNegate
    fromInteger :: Integer -> Natural
fromInteger Integer
i = Integer -> Natural
integerToNaturalThrow Integer
i
    abs :: Natural -> Natural
abs         = Natural -> Natural
forall a. a -> a
id
    signum :: Natural -> Natural
signum      = Natural -> Natural
naturalSignum

{-# DEPRECATED quotRemInteger "Use integerQuotRem# instead" #-}
quotRemInteger :: Integer -> Integer -> (# Integer, Integer #)
quotRemInteger :: Integer -> Integer -> (# Integer, Integer #)
quotRemInteger = Integer -> Integer -> (# Integer, Integer #)
integerQuotRem#