From 679fa960f964e42a61f10d1d517b20f03222d709 Mon Sep 17 00:00:00 2001 From: simonmar Date: Tue, 28 Sep 2004 11:29:29 +0000 Subject: [PATCH] [project @ 2004-09-28 11:29:29 by simonmar] - export foldl1' - specialise minimum/maximum for Integer too --- Data/List.hs | 23 +++++++++++++++-------- 1 file changed, 15 insertions(+), 8 deletions(-) diff --git a/Data/List.hs b/Data/List.hs index 7d4cf51..15088e9 100644 --- a/Data/List.hs +++ b/Data/List.hs @@ -42,6 +42,7 @@ module Data.List , foldl -- :: (a -> b -> a) -> a -> [b] -> a , foldl' -- :: (a -> b -> a) -> a -> [b] -> a , foldl1 -- :: (a -> a -> a) -> [a] -> a + , foldl1' -- :: (a -> a -> a) -> [a] -> a , foldr -- :: (a -> b -> b) -> b -> [a] -> b , foldr1 -- :: (a -> a -> a) -> [a] -> a @@ -462,14 +463,17 @@ maximum :: (Ord a) => [a] -> a maximum [] = errorEmptyList "maximum" maximum xs = foldl1 max xs -{-# RULES "maximumInt" maximum = maximumInt #-} +{-# RULES + "maximumInt" maximum = (strictMaximum :: [Int] -> Int); + "maximumInteger" maximum = (strictMaximum :: [Integer] -> Integer) + #-} -- We can't make the overloaded version of maximum strict without -- changing its semantics (max might not be strict), but we can for -- the version specialised to 'Int'. -maximumInt :: [Int] -> Int -maximumInt [] = errorEmptyList "maximum" -maximumInt xs = foldl1' max xs +strictMaximum :: (Ord a) => [a] -> a +strictMaximum [] = errorEmptyList "maximum" +strictMaximum xs = foldl1' max xs -- | 'minimum' returns the minimum value from a list, -- which must be non-empty, finite, and of an ordered type. @@ -479,11 +483,14 @@ minimum :: (Ord a) => [a] -> a minimum [] = errorEmptyList "minimum" minimum xs = foldl1 min xs -{-# RULES "minimumInt" minimum = minimumInt #-} +{-# RULES + "minimumInt" minimum = (strictMinimum :: [Int] -> Int); + "minimumInteger" minimum = (strictMinimum :: [Integer] -> Integer) + #-} -minimumInt :: [Int] -> Int -minimumInt [] = errorEmptyList "minimum" -minimumInt xs = foldl1' min xs +strictMinimum :: (Ord a) => [a] -> a +strictMinimum [] = errorEmptyList "minimum" +strictMinimum xs = foldl1' min xs -- | The 'maximumBy' function takes a comparison function and a list -- and returns the greatest element of the list by the comparison function. -- 1.7.10.4