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

More RULES for coercions and truncate.

ghc/lib/std/PrelFloat.lhs

@@ -163,10 +163,10 @@ instance  Fractional Float  where
     fromRational x	=  fromRat x
     recip x		=  1.0 / x
 
+{-# RULES "truncate/Float->Int" truncate = float2Int #-}
 instance  RealFrac Float  where
 
     {-# SPECIALIZE properFraction :: Float -> (Int, Float) #-}
-    {-# SPECIALIZE truncate :: Float -> Int #-}
     {-# SPECIALIZE round    :: Float -> Int #-}
     {-# SPECIALIZE ceiling  :: Float -> Int #-}
     {-# SPECIALIZE floor    :: Float -> Int #-}
@@ -326,10 +326,10 @@ instance  Floating Double  where
     acosh x = log (x + (x+1.0) * sqrt ((x-1.0)/(x+1.0)))
     atanh x = log ((x+1.0) / sqrt (1.0-x*x))
 
+{-# RULES "truncate/Double->Int" truncate = double2Int #-}
 instance  RealFrac Double  where
 
     {-# SPECIALIZE properFraction :: Double -> (Int, Double) #-}
-    {-# SPECIALIZE truncate :: Double -> Int #-}
     {-# SPECIALIZE round    :: Double -> Int #-}
     {-# SPECIALIZE ceiling  :: Double -> Int #-}
     {-# SPECIALIZE floor    :: Double -> Int #-}
@@ -827,6 +827,7 @@ int2Double   (I# x) = D# (int2Double#   x)
 
 double2Float :: Double -> Float
 double2Float (D# x) = F# (double2Float# x)
+
 float2Double :: Float -> Double
 float2Double (F# x) = D# (float2Double# x)
 

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}
-