X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Flib%2Fstd%2FPrelude.lhs;h=0f9aa1a8fd72d986d958b8106e1cbc8c92523ceb;hb=a76db2a07f99716c40e05d73210f80b4e4794b9a;hp=58de2745efe00cd2904c7fca17abefc908f4c447;hpb=cdc022f6f568886cee383427969d06451dd400c6;p=ghc-hetmet.git

diff --git a/ghc/lib/std/Prelude.lhs b/ghc/lib/std/Prelude.lhs
index 58de274..0f9aa1a 100644
--- a/ghc/lib/std/Prelude.lhs
+++ b/ghc/lib/std/Prelude.lhs
@@ -1,3 +1,11 @@
+% ------------------------------------------------------------------------------
+% $Id: Prelude.lhs,v 1.22 2000/06/30 13:39:36 simonmar Exp $
+%
+% (c) The University of Glasgow, 1992-2000
+%
+
+\section[Prelude]{Module @Prelude@}
+
 We add the option -fno-implicit-prelude here to tell the reader that
 special names such as () and -> shouldn't be resolved to Prelude.()
 and Prelude.-> (as they are normally). -- SDM 8/10/97
@@ -182,36 +190,34 @@ mapM_ f as      =  sequence_ (map f as)
 %*********************************************************
 
 \begin{code}
-{-# SPECIALIZE fromIntegral ::
-    Int		-> Rational,
-    Integer	-> Rational,
-    Int  	-> Int,
-    Int 	-> Integer,
-    Int		-> Float,
-    Int		-> Double,
-    Integer  	-> Int,
-    Integer 	-> Integer,
-    Integer	-> Float,
-    Integer	-> Double #-}
+{-# RULES
+"fromIntegral/Int->Int"                     fromIntegral   = id :: Int     -> Int
+"fromIntegral/Integer->Integer"             fromIntegral   = id :: Integer -> Integer
+"fromIntegral/Int->Integer"                 fromIntegral   = int2Integer
+"fromIntegral/Integer->Int"                 fromIntegral   = integer2Int
+"fromIntegral/Int->Rational"     forall n . fromIntegral n = int2Integer n :% 1
+"fromIntegral/Integer->Rational" forall n . fromIntegral n = n :% (1 :: Integer)
+"fromIntegral/Int->Float"                   fromIntegral   = int2Float
+"fromIntegral/Int->Double"                  fromIntegral   = int2Double
+"fromIntegral/Integer->Float"    forall n . fromIntegral n = encodeFloat n 0 :: Float
+"fromIntegral/Integer->Double"   forall n . fromIntegral n = encodeFloat n 0 :: Double
+ #-}
 fromIntegral	:: (Integral a, Num b) => a -> b
 fromIntegral	=  fromInteger . toInteger
 
-{-# SPECIALIZE realToFrac ::
-    Double	-> Rational, 
-    Rational	-> Double,
-    Float	-> Rational,
-    Rational	-> Float
- #-}
-realToFrac	:: (Real a, Fractional b) => a -> b
-realToFrac	=  fromRational . toRational
-
 {-# RULES
-"realToFrac/Double->Float"      realToFrac = doubleToFloat
 "realToFrac/Float->Double"      realToFrac = floatToDouble
-"realToFrac/Double->Double"     realToFrac = id :: Double -> Double
-"realToFrac/Float->Float"       realToFrac = id :: Float -> Float
-"realToFrac/Rational->Rational" realToFrac = id :: Rational -> Rational
+"realToFrac/Double->Float"      realToFrac = doubleToFloat
+"realToFrac/Float->Float"       realToFrac = id      :: Float    -> Float
+"realToFrac/Double->Double"     realToFrac = id      :: Double   -> Double
+"realToFrac/Rational->Rational" realToFrac = id      :: Rational -> Rational
+"realToFrac/Float->Rational"    realToFrac = rf2rat  :: Float    -> Rational
+"realToFrac/Double->Rational"   realToFrac = rf2rat  :: Double   -> Rational
+"realToFrac/Rational->Float"    realToFrac = fromRat :: Rational -> Float
+"realToFrac/Rational->Double"   realToFrac = fromRat :: Rational -> Double
  #-}
+realToFrac	:: (Real a, Fractional b) => a -> b
+realToFrac	=  fromRational . toRational
 
 doubleToFloat :: Double -> Float
 doubleToFloat (D# d) = F# (double2Float# d)
@@ -219,5 +225,12 @@ doubleToFloat (D# d) = F# (double2Float# d)
 floatToDouble :: Float -> Double
 floatToDouble (F# f) = D# (float2Double# f)
 
+{-# SPECIALIZE rf2rat ::
+    Float  -> Rational,
+    Double -> Rational
+ #-}
+rf2rat :: RealFloat a => a -> Rational
+rf2rat x = if n >= 0 then (m * (b ^ n)) :% 1 else m :% (b ^ (-n))
+   where (m,n) = decodeFloat x
+         b     = floatRadix  x
 \end{code}
-