[project @ 2000-05-10 15:16:11 by panne]

[ghc-hetmet.git] / ghc / lib / std / Prelude.lhs

diff --git a/ghc/lib/std/Prelude.lhs b/ghc/lib/std/Prelude.lhs
index 58de274..237db71 100644 (file)
--- a/ghc/lib/std/Prelude.lhs
+++ b/ghc/lib/std/Prelude.lhs
@@ -182,36 +182,34 @@ 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 +217,12 @@ 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}
-