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{-# LANGUAGE NoImplicitPrelude #-}
module Data.Ord (module Data.Eq,
Ordering (..),
Ord,
(<),
(<=),
(>),
(>=),
compare,
min,
max)
where
import Data.Eq
data Ordering = EQ | LT | GT
instance Eq Ordering where
EQ == EQ = True
LT == LT = True
GT == GT = True
_ == _ = False
infix 4 <, <=, >, >=
class Eq a => Ord a where
compare :: a -> a -> Ordering
(<), (>), (>=), (<=) :: a -> a -> Bool
min, max :: a -> a -> a
min x y = if (x <= y) then x else y
max x y = if (x >= y) then x else y
compare x y | x < y = LT
| x == y = EQ
| otherwise = GT
x < y = not (x >= y)
x > y = not (x <= y)
x >= y = x > y || x == y
x <= y = x < y || x == y
foreign import bpcall "Prelude:" lessthan_char :: Char -> Char -> Bool
foreign import bpcall "Prelude:" lessthan_int :: Int -> Int -> Bool
foreign import bpcall "Prelude:" lessthan_integer :: Integer -> Integer -> Bool
foreign import bpcall "Prelude:" lessthan_double :: Double -> Double -> Bool
instance Ord Char where
(<) = lessthan_char
instance Ord Int where
(<) = lessthan_int
instance Ord Integer where
(<) = lessthan_integer
instance Ord Double where
(<) = lessthan_double
instance Ord a => Ord [a] where
compare [] [] = EQ
compare [] (_:_) = LT
compare (_:_) [] = GT
compare (x:xs) (y:ys) = case compare x y of LT -> LT
GT -> GT
EQ -> compare xs ys
x < y = compare x y == LT
x > y = compare x y == GT
instance (Ord a, Ord b) => Ord (a,b) where
compare (x1,y1) (x2,y2) = let c1 = compare x1 x2
in case c1 of
EQ -> compare y1 y2
_ -> c1
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