Control.Exception doesn't need to export assertError

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

diff --git a/GHC/Real.lhs b/GHC/Real.lhs
index 8f39cf8..248268a 100644 (file)
--- a/GHC/Real.lhs
+++ b/GHC/Real.lhs
@@ -1,5 +1,5 @@
 \begin{code}
-{-# OPTIONS_GHC -fno-implicit-prelude #-}
+{-# OPTIONS_GHC -XNoImplicitPrelude #-}
 {-# OPTIONS_HADDOCK hide #-}
 -----------------------------------------------------------------------------
 -- |
@@ -201,10 +201,10 @@ These 'numeric' enumerations come straight from the Report
 
 \begin{code}
 numericEnumFrom         :: (Fractional a) => a -> [a]
-numericEnumFrom         =  iterate (+1)
+numericEnumFrom n      =  n `seq` (n : numericEnumFrom (n + 1))
 
 numericEnumFromThen     :: (Fractional a) => a -> a -> [a]
-numericEnumFromThen n m =  iterate (+(m-n)) 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)
@@ -408,11 +408,15 @@ odd             =  not . even
 (^) :: (Num a, Integral b) => a -> b -> a
 x0 ^ y0 | y0 < 0    = error "Negative exponent"
         | y0 == 0   = 1
-        | otherwise = f x0 y0 1
-    where -- x0 ^ y0 = (x ^ y) * z
-          f x y z | even y = f (x * x) (y `quot` 2) z
+        | otherwise = f x0 y0
+    where -- f : x0 ^ y0 = x ^ y
+          f x y | even y    = f (x * x) (y `quot` 2)
+                | y == 1    = x
+                | otherwise = g (x * x) ((y - 1) `quot` 2) x
+          -- g : x0 ^ y0 = (x ^ y) * z
+          g x y z | even y = g (x * x) (y `quot` 2) z
                   | y == 1 = x * z
-                  | otherwise = f (x * x) ((y - 1) `quot` 2) (x * z)
+                  | otherwise = g (x * x) ((y - 1) `quot` 2) (x * z)
 
 -- | raise a number to an integral power
 {-# SPECIALISE (^^) ::