[project @ 2001-01-17 15:23:39 by sewardj]

[ghc-hetmet.git] / ghc / interpreter / library / Ratio.hs

diff --git a/ghc/interpreter/library/Ratio.hs b/ghc/interpreter/library/Ratio.hs
deleted file mode 100644 (file)
index e301438..0000000
--- a/ghc/interpreter/library/Ratio.hs
+++ /dev/null
@@ -1,103 +0,0 @@
--- Standard functions on rational numbers
-
-#ifdef HEAD
-module  Ratio (
-    Ratio, Rational, (%), numerator, denominator, approxRational ) where
-
-#if STD_PRELUDE
-infixl 7  %
-#endif
-
-import PreludeBuiltin
-#endif /* HEAD */
-#ifdef BODY
-
-data  (Integral a)      => Ratio a = !a :% !a  deriving (Eq)
-type  Rational          =  Ratio BIGNUMTYPE
-
-(%)                     :: (Integral a) => a -> a -> Ratio a
-numerator, denominator  :: (Integral a) => Ratio a -> a
-approxRational          :: (RealFrac a) => a -> a -> Rational
-
-
--- "reduce" is a subsidiary function used only in this module.
--- It normalises a ratio by dividing both numerator
--- and denominator by their greatest common divisor.
---
--- E.g., 12 `reduce` 8    ==  3 :%   2
---       12 `reduce` (-8) ==  3 :% (-2)
-
-reduce _ 0              =  error "Ratio.% : zero denominator"
-reduce x y              =  (x `quot` d) :% (y `quot` d)
-                           where d = gcd x y
-
-x % y                   =  reduce (x * signum y) (abs y)
-
-numerator   (x :% _)   =  x
-
-denominator (_ :% y)   =  y
-
-
-instance  (Integral a)  => Ord (Ratio a)  where
-    (x:%y) <= (x':%y')  =  x * y' <= x' * y
-    (x:%y) <  (x':%y')  =  x * y' <  x' * y
-
-instance  (Integral a)  => Num (Ratio a)  where
-    (x:%y) + (x':%y')   =  reduce (x*y' + x'*y) (y*y')
-    (x:%y) * (x':%y')   =  reduce (x * x') (y * y')
-    negate (x:%y)       =  (-x) :% y
-    abs (x:%y)          =  abs x :% y
-    signum (x:%y)       =  signum x :% 1
-    fromInteger x       =  fromInteger x :% 1
-
-instance  (Integral a)  => Real (Ratio a)  where
-    toRational (x:%y)   =  toInteger x :% toInteger y
-
-instance  (Integral a)  => Fractional (Ratio a)  where
-    (x:%y) / (x':%y')   =  (x*y') % (y*x')
-    recip (x:%y)        =  if x < 0 then (-y) :% (-x) else y :% x
-    fromRational (x:%y) =  fromInteger x :% fromInteger y
-
-instance  (Integral a)  => RealFrac (Ratio a)  where
-    properFraction (x:%y) = (fromIntegral q, r:%y)
-                            where (q,r) = quotRem x y
-
-instance  (Integral a)  => Enum (Ratio a)  where
-    enumFrom           =  numericEnumFrom
-    enumFromThen       =  numericEnumFromThen
-    enumFromTo         =  numericEnumFromTo
-    enumFromThenTo     =  numericEnumFromThenTo
-    toEnum              =  fromInteger . toInteger
-    fromEnum n          =  error "Ratio.fromEnum: can't use\ 
-                                  \ fromEnum with Ratio"
-
-instance  (Read a, Integral a)  => Read (Ratio a)  where
-    readsPrec p  =  readParen (p > 7)
-                              (\r -> [(x%y,u) | (x,s)   <- reads r,
-                                                ("%",t) <- lex s,
-                                                (y,u)   <- reads t ])
-
-instance  (Integral a)  => Show (Ratio a)  where
-    showsPrec p (x:%y)  =  showParen (p > 7)
-                               (shows x . showString " % " . shows y)
-
-
-
-approxRational x eps    =  simplest (x-eps) (x+eps)
-        where simplest x y | y < x      =  simplest y x
-                           | x == y     =  xr
-                           | x > 0      =  simplest' n d n' d'
-                           | y < 0      =  - simplest' (-n') d' (-n) d
-                           | otherwise  =  0 :% 1
-                                        where xr@(n:%d) = toRational x
-                                              (n':%d')  = toRational y
-
-              simplest' n d n' d'       -- assumes 0 < n%d < n'%d'
-                        | r == 0     =  q :% 1
-                        | q /= q'    =  (q+1) :% 1
-                        | otherwise  =  (q*n''+d'') :% n''
-                                     where (q,r)      =  quotRem n d
-                                           (q',r')    =  quotRem n' d'
-                                           (n'':%d'') =  simplest' d' r' d r
-
-#endif /* BODY */