[project @ 2002-02-12 11:44:54 by simonmar]

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

diff --git a/ghc/lib/std/PrelReal.lhs b/ghc/lib/std/PrelReal.lhs
index acc4877..cd2c1c0 100644 (file)
--- a/ghc/lib/std/PrelReal.lhs
+++ b/ghc/lib/std/PrelReal.lhs
@@ -1,5 +1,5 @@
 % ------------------------------------------------------------------------------
-% $Id: PrelReal.lhs,v 1.9 2001/02/22 16:48:24 qrczak Exp $
+% $Id: PrelReal.lhs,v 1.16 2001/09/26 16:27:04 simonpj Exp $
 %
 % (c) The University of Glasgow, 1994-2000
 %
@@ -62,6 +62,7 @@ their greatest common divisor.
 
 \begin{code}
 reduce ::  (Integral a) => a -> a -> Ratio a
+{-# SPECIALISE reduce :: Integer -> Integer -> Rational #-}
 reduce _ 0             =  error "Ratio.%: zero denominator"
 reduce x y             =  (x `quot` d) :% (y `quot` d)
                           where d = gcd x y
@@ -97,10 +98,6 @@ class  (Real a, Enum a) => Integral a  where
     divMod n d                 =  if signum r == negate (signum d) then (q-1, r+d) else qr
                           where qr@(q,r) = quotRem n d
 
-toInt :: Integral a => a -> Int
--- For backward compatibility
-toInt i = fromInteger (toInteger i)
-
 class  (Num a) => Fractional a  where
     (/)                        :: a -> a -> a
     recip              :: a -> a
@@ -230,7 +227,7 @@ instance  (Integral a)      => Num (Ratio a)  where
 instance  (Integral a) => Fractional (Ratio a)  where
     {-# SPECIALIZE instance Fractional Rational #-}
     (x:%y) / (x':%y')  =  (x*y') % (y*x')
-    recip (x:%y)       =  if x < 0 then (-y) :% (-x) else y :% x
+    recip (x:%y)       =  y % x
     fromRational (x:%y) =  fromInteger x :% fromInteger y
 
 instance  (Integral a) => Real (Ratio a)  where
@@ -267,6 +264,38 @@ instance  (Integral a)     => Enum (Ratio a)  where
 
 %*********************************************************
 %*                                                     *
+\subsection{Coercions}
+%*                                                     *
+%*********************************************************
+
+\begin{code}
+fromIntegral :: (Integral a, Num b) => a -> b
+fromIntegral = fromInteger . toInteger
+
+{-# RULES
+"fromIntegral/Int->Int" fromIntegral = id :: Int -> Int
+    #-}
+
+realToFrac :: (Real a, Fractional b) => a -> b
+realToFrac = fromRational . toRational
+
+{-# RULES
+"realToFrac/Int->Int" realToFrac = id :: Int -> Int
+    #-}
+
+-- For backward compatibility
+{-# DEPRECATED fromInt "use fromIntegral instead" #-}
+fromInt :: Num a => Int -> a
+fromInt = fromIntegral
+
+-- For backward compatibility
+{-# DEPRECATED toInt "use fromIntegral instead" #-}
+toInt :: Integral a => a -> Int
+toInt = fromIntegral
+\end{code}
+
+%*********************************************************
+%*                                                     *
 \subsection{Overloaded numeric functions}
 %*                                                     *
 %*********************************************************
@@ -320,4 +349,22 @@ lcm x y            =  abs ((x `quot` (gcd x y)) * y)
 "gcd/Integer->Integer->Integer" gcd = gcdInteger
 "lcm/Integer->Integer->Integer" lcm = lcmInteger
  #-}
+
+integralEnumFrom :: (Integral a, Bounded a) => a -> [a]
+integralEnumFrom n = map fromInteger [toInteger n .. toInteger (maxBound `asTypeOf` n)]
+
+integralEnumFromThen :: (Integral a, Bounded a) => a -> a -> [a]
+integralEnumFromThen n1 n2
+  | i_n2 >= i_n1  = map fromInteger [i_n1, i_n2 .. toInteger (maxBound `asTypeOf` n1)]
+  | otherwise     = map fromInteger [i_n1, i_n2 .. toInteger (minBound `asTypeOf` n1)]
+  where
+    i_n1 = toInteger n1
+    i_n2 = toInteger n2
+
+integralEnumFromTo :: Integral a => a -> a -> [a]
+integralEnumFromTo n m = map fromInteger [toInteger n .. toInteger m]
+
+integralEnumFromThenTo :: Integral a => a -> a -> a -> [a]
+integralEnumFromThenTo n1 n2 m
+  = map fromInteger [toInteger n1, toInteger n2 .. toInteger m]
 \end{code}