Data/Floating/Types.hs

   1 {-
   2  - Copyright (C) 2009-2010 Nick Bowler.
   3  -
   4  - License BSD2:  2-clause BSD license.  See LICENSE for full terms.
   5  - This is free software: you are free to change and redistribute it.
   6  - There is NO WARRANTY, to the extent permitted by law.
   7  -}
   8
   9 -- | Definition of the core floating point types and basic manipulation of
  10 -- them.
  11 {-# LANGUAGE MultiParamTypeClasses, FlexibleInstances, OverlappingInstances #-}
  12 {-# LANGUAGE MagicHash #-}
  13 module Data.Floating.Types (
  14     Double(..), Float(..), FloatConvert(..)
  15 ) where
  16
  17 import Prelude hiding (Double, Float)
  18 import qualified GHC.Exts as GHC
  19 import GHC.Integer
  20 import GHC.Prim
  21 import Foreign.C
  22
  23 import Data.Ratio
  24
  25 import Unsafe.Coerce
  26
  27 -- | The Double type.  This is expected to be an identical declaration to
  28 -- the one found in GHC.Prim.  We avoid simply using GHC's type because we need
  29 -- to define our own class instances.
  30 data Double = D# Double#
  31
  32 -- | The Float type.
  33 data Float  = F# Float#
  34
  35 -- | Coercion to floating point types.
  36 class FloatConvert a b where
  37     -- | Convert to a floating point type.  Conversions from integers and real
  38     -- types are provided, as well as conversions between floating point types.
  39     -- Conversions between floating point types preserve infinities, negative
  40     -- zeros and NaNs.
  41     toFloating :: a -> b
  42
  43 instance FloatConvert Double CDouble where
  44     toFloating = unsafeCoerce
  45
  46 instance FloatConvert CDouble Double where
  47     toFloating = unsafeCoerce
  48
  49 instance FloatConvert Float CFloat where
  50     toFloating = unsafeCoerce
  51
  52 instance FloatConvert CFloat Float where
  53     toFloating = unsafeCoerce
  54
  55 instance FloatConvert Double Float where
  56     toFloating (D# x) = F# (double2Float# x)
  57
  58 instance FloatConvert Float Double where
  59     toFloating (F# x) = D# (float2Double# x)
  60
  61 instance FloatConvert Integer Double where
  62     toFloating x = D# (doubleFromInteger x)
  63
  64 instance FloatConvert Integer Float where
  65     toFloating x = F# (floatFromInteger x)
  66
  67 instance Real a => FloatConvert a Double where
  68     toFloating x = D# (num /## denom) where
  69         !(D# num)   = toFloating . numerator   . toRational $ x
  70         !(D# denom) = toFloating . denominator . toRational $ x
  71
  72 instance Real a => FloatConvert a Float where
  73     toFloating x = F# (divideFloat# num denom) where
  74         !(F# num)   = toFloating . numerator   . toRational $ x
  75         !(F# denom) = toFloating . denominator . toRational $ x
  76
  77 instance FloatConvert a a where
  78     toFloating = id