Remove an old comment

[ghc-base.git] / GHC / Real.lhs

diff --git a/GHC/Real.lhs b/GHC/Real.lhs
index 6d1f6e0..971f276 100644 (file)
--- a/GHC/Real.lhs
+++ b/GHC/Real.lhs
@@ -4,7 +4,7 @@
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  GHC.Real
--- Copyright   :  (c) The FFI Task Force, 1994-2002
+-- Copyright   :  (c) The University of Glasgow, 1994-2002
 -- License     :  see libraries/base/LICENSE
 -- 
 -- Maintainer  :  cvs-ghc@haskell.org
@@ -24,6 +24,7 @@ import GHC.Num
 import GHC.List
 import GHC.Enum
 import GHC.Show
+import GHC.Err
 
 infixr 8  ^, ^^
 infixl 7  /, `quot`, `rem`, `div`, `mod`
@@ -132,10 +133,15 @@ class  (Real a, Enum a) => Integral a  where
     -- | conversion to 'Integer'
     toInteger           :: a -> Integer
 
+    {-# INLINE quot #-}
+    {-# INLINE rem #-}
+    {-# INLINE div #-}
+    {-# INLINE mod #-}
     n `quot` d          =  q  where (q,_) = quotRem n d
     n `rem` d           =  r  where (_,r) = quotRem n d
     n `div` d           =  q  where (q,_) = divMod n d
     n `mod` d           =  r  where (_,r) = divMod n d
+
     divMod n d          =  if signum r == negate (signum d) then (q-1, r+d) else qr
                            where qr@(q,r) = quotRem n d
 
@@ -153,6 +159,8 @@ class  (Num a) => Fractional a  where
     -- @('Fractional' a) => a@.
     fromRational        :: Rational -> a
 
+    {-# INLINE recip #-}
+    {-# INLINE (/) #-}
     recip x             =  1 / x
     x / y               = x * recip y
 
@@ -173,13 +181,15 @@ class  (Real a, Fractional a) => RealFrac a  where
     properFraction      :: (Integral b) => a -> (b,a)
     -- | @'truncate' x@ returns the integer nearest @x@ between zero and @x@
     truncate            :: (Integral b) => a -> b
-    -- | @'round' x@ returns the nearest integer to @x@
+    -- | @'round' x@ returns the nearest integer to @x@;
+    --   the even integer if @x@ is equidistant between two integers
     round               :: (Integral b) => a -> b
     -- | @'ceiling' x@ returns the least integer not less than @x@
     ceiling             :: (Integral b) => a -> b
     -- | @'floor' x@ returns the greatest integer not greater than @x@
     floor               :: (Integral b) => a -> b
 
+    {-# INLINE truncate #-}
     truncate x          =  m  where (m,_) = properFraction x
     
     round x             =  let (n,r) = properFraction x
@@ -188,6 +198,7 @@ class  (Real a, Fractional a) => RealFrac a  where
                                 -1 -> n
                                 0  -> if even n then n else m
                                 1  -> m
+                                _  -> error "round default defn: Bad value"
     
     ceiling x           =  if r > 0 then n + 1 else n
                            where (n,r) = properFraction x
@@ -201,20 +212,21 @@ These 'numeric' enumerations come straight from the Report
 
 \begin{code}
 numericEnumFrom         :: (Fractional a) => a -> [a]
-numericEnumFrom n      =  numericEnumFromThen n (n + 1)
+numericEnumFrom n      =  n `seq` (n : numericEnumFrom (n + 1))
 
 numericEnumFromThen     :: (Fractional a) => a -> a -> [a]
-numericEnumFromThen n m        = n `seq` m `seq` n : numericEnumFromThen m (m+m-n)
+numericEnumFromThen n m        = n `seq` m `seq` (n : numericEnumFromThen m (m+m-n))
 
 numericEnumFromTo       :: (Ord a, Fractional a) => a -> a -> [a]
 numericEnumFromTo n m   = takeWhile (<= m + 1/2) (numericEnumFrom n)
 
 numericEnumFromThenTo   :: (Ord a, Fractional a) => a -> a -> a -> [a]
-numericEnumFromThenTo e1 e2 e3 = takeWhile pred (numericEnumFromThen e1 e2)
+numericEnumFromThenTo e1 e2 e3
+    = takeWhile predicate (numericEnumFromThen e1 e2)
                                 where
                                  mid = (e2 - e1) / 2
-                                 pred | e2 >= e1  = (<= e3 + mid)
-                                      | otherwise = (>= e3 + mid)
+                                 predicate | e2 >= e1  = (<= e3 + mid)
+                                           | otherwise = (>= e3 + mid)
 \end{code}
 
 
@@ -276,17 +288,17 @@ instance  Real Integer  where
 instance  Integral Integer where
     toInteger n      = n
 
-    a `quot` 0 = divZeroError
+    _ `quot` 0 = divZeroError
     n `quot` d = n `quotInteger` d
 
-    a `rem` 0 = divZeroError
+    _ `rem` 0 = divZeroError
     n `rem`  d = n `remInteger`  d
 
-    a `divMod` 0 = divZeroError
+    _ `divMod` 0 = divZeroError
     a `divMod` b = case a `divModInteger` b of
                    (# x, y #) -> (x, y)
 
-    a `quotRem` 0 = divZeroError
+    _ `quotRem` 0 = divZeroError
     a `quotRem` b = case a `quotRemInteger` b of
                     (# q, r #) -> (q, r)
 
@@ -335,8 +347,11 @@ instance  (Integral a)  => Show (Ratio a)  where
     {-# SPECIALIZE instance Show Rational #-}
     showsPrec p (x:%y)  =  showParen (p > ratioPrec) $
                            showsPrec ratioPrec1 x . 
-                           showString "%" .     -- H98 report has spaces round the %
-                                                -- but we removed them [May 04]
+                           showString " % " .
+                           -- H98 report has spaces round the %
+                           -- but we removed them [May 04]
+                           -- and added them again for consistency with
+                           -- Haskell 98 [Sep 08, #1920]
                            showsPrec ratioPrec1 y
 
 instance  (Integral a)  => Enum (Ratio a)  where
@@ -442,18 +457,21 @@ lcm _ 0         =  0
 lcm 0 _         =  0
 lcm x y         =  abs ((x `quot` (gcd x y)) * y)
 
+#ifdef OPTIMISE_INTEGER_GCD_LCM
 {-# RULES
 "gcd/Int->Int->Int"             gcd = gcdInt
+"gcd/Integer->Integer->Integer" gcd = gcdInteger'
+"lcm/Integer->Integer->Integer" lcm = lcmInteger
  #-}
 
--- XXX these optimisation rules are disabled for now to make it easier
---     to experiment with other Integer implementations
--- "gcd/Integer->Integer->Integer" gcd = gcdInteger'
--- "lcm/Integer->Integer->Integer" lcm = lcmInteger
---
--- gcdInteger' :: Integer -> Integer -> Integer
--- gcdInteger' 0 0 = error "GHC.Real.gcdInteger': gcd 0 0 is undefined"
--- gcdInteger' a b = gcdInteger a b
+gcdInteger' :: Integer -> Integer -> Integer
+gcdInteger' 0 0 = error "GHC.Real.gcdInteger': gcd 0 0 is undefined"
+gcdInteger' a b = gcdInteger a b
+
+gcdInt :: Int -> Int -> Int
+gcdInt 0 0 = error "GHC.Real.gcdInt: gcd 0 0 is undefined"
+gcdInt a b = fromIntegral (gcdInteger (fromIntegral a) (fromIntegral b))
+#endif
 
 integralEnumFrom :: (Integral a, Bounded a) => a -> [a]
 integralEnumFrom n = map fromInteger [toInteger n .. toInteger (maxBound `asTypeOf` n)]