Remove Control.Parallel*, now in package parallel

[haskell-directory.git] / Data / Ratio.hs

diff --git a/Data/Ratio.hs b/Data/Ratio.hs
index d71551e..22f3abe 100644 (file)
--- a/Data/Ratio.hs
+++ b/Data/Ratio.hs
@@ -2,14 +2,12 @@
 -- |
 -- Module      :  Data.Ratio
 -- Copyright   :  (c) The University of Glasgow 2001
--- License     :  BSD-style (see the file libraries/core/LICENSE)
+-- License     :  BSD-style (see the file libraries/base/LICENSE)
 -- 
 -- Maintainer  :  libraries@haskell.org
--- Stability   :  provisional
+-- Stability   :  stable
 -- Portability :  portable
 --
--- $Id: Ratio.hs,v 1.2 2002/04/24 16:31:40 simonmar Exp $
---
 -- Standard functions on rational numbers
 --
 -----------------------------------------------------------------------------
@@ -41,14 +39,29 @@ import Prelude
 import GHC.Real                -- The basic defns for Ratio
 #endif
 
+#ifdef __HUGS__
+import Hugs.Prelude(Ratio(..), (%), numerator, denominator)
+#endif
+
+#ifdef __NHC__
+import Ratio (Ratio(..), (%), numerator, denominator, approxRational)
+#else
+
 -- -----------------------------------------------------------------------------
 -- approxRational
 
--- @approxRational@, applied to two real fractional numbers x and epsilon,
--- returns the simplest rational number within epsilon of x.  A rational
--- number n%d in reduced form is said to be simpler than another n'%d' if
--- abs n <= abs n' && d <= d'.  Any real interval contains a unique
--- simplest rational; here, for simplicity, we assume a closed rational
+-- | 'approxRational', applied to two real fractional numbers @x@ and @epsilon@,
+-- returns the simplest rational number within @epsilon@ of @x@.
+-- A rational number @y@ is said to be /simpler/ than another @y'@ if
+--
+-- * @'abs' ('numerator' y) <= 'abs' ('numerator' y')@, and
+--
+-- * @'denominator' y <= 'denominator' y'@.
+--
+-- Any real interval contains a unique simplest rational;
+-- in particular, note that @0\/1@ is the simplest rational of all.
+
+-- Implementation details: Here, for simplicity, we assume a closed rational
 -- interval.  If such an interval includes at least one whole number, then
 -- the simplest rational is the absolutely least whole number.  Otherwise,
 -- the bounds are of the form q%1 + r%d and q%1 + r'%d', where abs r < d
@@ -78,4 +91,4 @@ approxRational rat eps        =  simplest (rat-eps) (rat+eps)
                                           nd''       =  simplest' d' r' d r
                                           n''        =  numerator nd''
                                           d''        =  denominator nd''
-
+#endif