X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=Data%2FList.hs;h=2a37187899045ffd11198db16aa80c76f5d99d1a;hb=9fa9bc17072a58c0bae2cce4764d38677e96ac29;hp=ce4c9b32f23ebbe886a168baea5a4b6f51035013;hpb=7f1f4e7a695c402ddd3a1dc2cc7114e649a78ebc;p=ghc-base.git

diff --git a/Data/List.hs b/Data/List.hs
index ce4c9b3..2a37187 100644
--- a/Data/List.hs
+++ b/Data/List.hs
@@ -1,6 +1,6 @@
 {-# OPTIONS -fno-implicit-prelude #-}
 -----------------------------------------------------------------------------
--- 
+-- |
 -- Module      :  Data.List
 -- Copyright   :  (c) The University of Glasgow 2001
 -- License     :  BSD-style (see the file libraries/core/LICENSE)
@@ -9,7 +9,7 @@
 -- Stability   :  provisional
 -- Portability :  portable
 --
--- $Id: List.hs,v 1.1 2001/06/28 14:15:02 simonmar Exp $
+-- $Id: List.hs,v 1.4 2002/04/24 16:31:39 simonmar Exp $
 --
 -- Operations on lists.
 --
@@ -90,6 +90,7 @@ module Data.List
    , length	       -- :: [a] -> Int
    , (!!)	       -- :: [a] -> Int -> a
    , foldl	       -- :: (a -> b -> a) -> a -> [b] -> a
+   , foldl'	       -- :: (a -> b -> a) -> a -> [b] -> a
    , foldl1	       -- :: (a -> a -> a) -> [a] -> a
    , scanl             -- :: (a -> b -> a) -> a -> [b] -> [a]
    , scanl1            -- :: (a -> a -> a) -> [a] -> [a]
@@ -317,13 +318,21 @@ insertBy cmp x ys@(y:ys')
      GT -> y : insertBy cmp x ys'
      _  -> x : ys
 
-maximumBy		:: (a -> a -> a) -> [a] -> a
-maximumBy _   []	=  error "List.maximumBy: empty list"
-maximumBy max xs	=  foldl1 max xs
-
-minimumBy		:: (a -> a -> a) -> [a] -> a
-minimumBy _   []	=  error "List.minimumBy: empty list"
-minimumBy min xs	=  foldl1 min xs
+maximumBy		:: (a -> a -> Ordering) -> [a] -> a
+maximumBy _ []		=  error "List.maximumBy: empty list"
+maximumBy cmp xs	=  foldl1 max xs
+			where
+			   max x y = case cmp x y of
+					GT -> x
+					_  -> y
+
+minimumBy		:: (a -> a -> Ordering) -> [a] -> a
+minimumBy _ []		=  error "List.minimumBy: empty list"
+minimumBy cmp xs	=  foldl1 min xs
+			where
+			   min x y = case cmp x y of
+					GT -> y
+					_  -> x
 
 genericLength           :: (Num i) => [b] -> i
 genericLength []        =  0
@@ -513,6 +522,14 @@ unfoldr f b  =
    Just (a,new_b) -> a : unfoldr f new_b
    Nothing        -> []
 
+
+-- -----------------------------------------------------------------------------
+-- strict version of foldl
+
+foldl'           :: (a -> b -> a) -> a -> [b] -> a
+foldl' f a []     = a
+foldl' f a (x:xs) = let a' = f a x in a' `seq` foldl' f a' xs
+
 -- -----------------------------------------------------------------------------
 -- List sum and product