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(..), Complex(..)
  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.Floating.Classes
  24 import Data.Ratio
  25
  26 import Unsafe.Coerce
  27
  28 -- | The Double type.  This is expected to be an identical declaration to
  29 -- the one found in GHC.Prim.  We avoid simply using GHC's type because we need
  30 -- to define our own class instances.
  31 data Double = D# Double#
  32
  33 -- | The Float type.
  34 data Float  = F# Float#
  35
  36 infix 6 :+
  37 -- | Complex numbers.
  38 data (PrimFloat a) => Complex a = !a :+ !a
  39     deriving Eq
  40
  41 -- | Coercion to floating point types.
  42 class FloatConvert a b where
  43     -- | Convert to a floating point type.  Conversions from integers and real
  44     -- types are provided, as well as conversions between floating point types.
  45     -- Conversions between floating point types preserve infinities, negative
  46     -- zeros and NaNs.
  47     toFloating :: a -> b
  48
  49 instance FloatConvert Double CDouble where
  50     toFloating = unsafeCoerce
  51
  52 instance FloatConvert CDouble Double where
  53     toFloating = unsafeCoerce
  54
  55 instance FloatConvert Float CFloat where
  56     toFloating = unsafeCoerce
  57
  58 instance FloatConvert CFloat Float where
  59     toFloating = unsafeCoerce
  60
  61 instance FloatConvert Double Float where
  62     toFloating (D# x) = F# (double2Float# x)
  63
  64 instance FloatConvert Float Double where
  65     toFloating (F# x) = D# (float2Double# x)
  66
  67 instance FloatConvert Integer Double where
  68     toFloating x = D# (doubleFromInteger x)
  69
  70 instance FloatConvert Integer Float where
  71     toFloating x = F# (floatFromInteger x)
  72
  73 instance Real a => FloatConvert a Double where
  74     toFloating x = D# (num /## denom) where
  75         !(D# num)   = toFloating . numerator   . toRational $ x
  76         !(D# denom) = toFloating . denominator . toRational $ x
  77
  78 instance Real a => FloatConvert a Float where
  79     toFloating x = F# (divideFloat# num denom) where
  80         !(F# num)   = toFloating . numerator   . toRational $ x
  81         !(F# denom) = toFloating . denominator . toRational $ x
  82
  83 instance FloatConvert a a where
  84     toFloating = id