\begin{code}
module List (
- delete, deleteBy, (\\), deleteFirsts, deleteFirstsBy,
- elemBy, notElemBy, lookupBy, maximumBy, minimumBy,
- nub, nubBy, partition, sums, products, transpose,
+ elemIndex, elemIndices,
+ find, findIndex, findIndices,
+ nub, nubBy, delete, deleteBy, (\\), union, intersect,
+ intersperse, transpose, partition,
+ mapAccumL, mapAccumR,
+ sort, sortBy, insertBy,
+ maximumBy, minimumBy,
+ genericLength, genericTake, genericDrop,
+ genericSplitAt, genericIndex,
zip4, zip5, zip6, zip7,
zipWith4, zipWith5, zipWith6, zipWith7,
- unzip4, unzip5, unzip6, unzip7,
- genericLength, genericDrop, genericTake, genericSplitAt,
- genericReplicate,
- elemIndex, elemIndexBy, intersperse, group, groupBy,
- mapAccumL, mapAccumR,
- inits, tails, subsequences, permutations,
- union, intersect
+ unzip4, unzip5, unzip6, unzip7
+
+{- Disappeared from 1.4 libs - include still?
+ sums, products,
+ elemIndexBy, group, groupBy,
+ inits, tails, subsequences, permutations
+-}
+
) where
import Prelude
+import Maybe (listToMaybe)
+
+infix 5 \\
\end{code}
%*********************************************************
%*********************************************************
\begin{code}
+elemIndex :: Eq a => a -> [a] -> Maybe Int
+elemIndex x = findIndex (x==)
+
+elemIndices :: Eq a => a -> [a] -> [Int]
+elemIndices x = findIndices (x==)
+
+find :: (a -> Bool) -> [a] -> Maybe a
+find p = listToMaybe . filter p
+
+findIndex :: (a -> Bool) -> [a] -> Maybe Int
+findIndex p = listToMaybe . findIndices p
+
+findIndices :: (a -> Bool) -> [a] -> [Int]
+findIndices p xs = [ i | (x,i) <- zip xs [0..], p x]
+
+-- nub (meaning "essence") remove duplicate elements from its list argument.
+nub :: (Eq a) => [a] -> [a]
+nub = nubBy (==)
+
+nubBy :: (a -> a -> Bool) -> [a] -> [a]
+nubBy eq [] = []
+nubBy eq (x:xs) = x : nubBy eq (filter (\ y -> not (eq x y)) xs)
+
-- delete x removes the first occurrence of x from its list argument.
delete :: (Eq a) => a -> [a] -> [a]
delete = deleteBy (==)
(\\) :: (Eq a) => [a] -> [a] -> [a]
(\\) = foldl (flip delete)
--- Alternate name for \\
-deleteFirsts :: (Eq a) => [a] -> [a] -> [a]
-deleteFirsts = (\\)
+-- List union, remove the elements of first list from second.
+union :: (Eq a) => [a] -> [a] -> [a]
+union xs ys = xs ++ (ys \\ xs)
-deleteFirstsBy :: (a -> a -> Bool) -> [a] -> [a] -> [a]
-deleteFirstsBy eq = foldl (flip (deleteBy eq))
+intersect :: (Eq a) => [a] -> [a] -> [a]
+intersect xs ys = [ x | x <- xs, x `elem` ys]
--- elem, notElem, lookup, maximumBy and minimumBy are in PreludeList
-elemBy, notElemBy :: (a -> a -> Bool) -> a -> [a] -> Bool
-elemBy eq _ [] = False
-elemBy eq x (y:ys) = x `eq` y || elemBy eq x ys
+-- intersperse sep inserts sep between the elements of its list argument.
+-- e.g. intersperse ',' "abcde" == "a,b,c,d,e"
+intersperse :: a -> [a] -> [a]
+intersperse sep [] = []
+intersperse sep [x] = [x]
+intersperse sep (x:xs) = x : sep : intersperse sep xs
-notElemBy eq x xs = not (elemBy eq x xs)
+transpose :: [[a]] -> [[a]]
+transpose = foldr
+ (\xs xss -> zipWith (:) xs (xss ++ repeat []))
+ []
-lookupBy :: (a -> a -> Bool) -> a -> [(a, b)] -> Maybe b
-lookupBy eq key [] = Nothing
-lookupBy eq key ((x,y):xys)
- | key `eq` x = Just y
- | otherwise = lookupBy eq key xys
+
+-- partition takes a predicate and a list and returns a pair of lists:
+-- those elements of the argument list that do and do not satisfy the
+-- predicate, respectively; i,e,,
+-- partition p xs == (filter p xs, filter (not . p) xs).
+partition :: (a -> Bool) -> [a] -> ([a],[a])
+partition p xs = foldr select ([],[]) xs
+ where select x (ts,fs) | p x = (x:ts,fs)
+ | otherwise = (ts, x:fs)
+
+
+
+
+mapAccumL :: (a -> b -> (a, c)) -> a -> [b] -> (a, [c])
+mapAccumL f s [] = (s, [])
+mapAccumL f s (x:xs) = (s'',y:ys)
+ where (s', y ) = f s x
+ (s'',ys) = mapAccumL f s' xs
+
+mapAccumR :: (a -> b -> (a, c)) -> a -> [b] -> (a, [c])
+mapAccumR f s [] = (s, [])
+mapAccumR f s (x:xs) = (s'', y:ys)
+ where (s'',y ) = f s' x
+ (s', ys) = mapAccumR f s xs
+sort :: (Ord a) => [a] -> [a]
+sort = sortBy compare
+
+sortBy :: (a -> a -> Ordering) -> [a] -> [a]
+sortBy cmp = foldr (insertBy cmp) []
+
+insertBy :: (a -> a -> Ordering) -> a -> [a] -> [a]
+insertBy cmp x [] = [x]
+insertBy cmp x ys@(y:ys')
+ = case cmp x y of
+ GT -> y : insertBy cmp x ys'
+ _ -> x : ys
maximumBy :: (a -> a -> a) -> [a] -> a
maximumBy max [] = error "List.maximumBy: empty list"
minimumBy min [] = error "List.minimumBy: empty list"
minimumBy min xs = foldl1 min xs
--- nub (meaning "essence") remove duplicate elements from its list argument.
-nub :: (Eq a) => [a] -> [a]
-nub = nubBy (==)
+genericLength :: (Num i) => [b] -> i
+genericLength [] = 0
+genericLength (_:l) = 1 + genericLength l
-nubBy :: (a -> a -> Bool) -> [a] -> [a]
-nubBy eq [] = []
-nubBy eq (x:xs) = x : nubBy eq (filter (\ y -> not (eq x y)) xs)
+genericTake :: (Integral i) => i -> [a] -> [a]
+genericTake 0 _ = []
+genericTake _ [] = []
+genericTake n (x:xs) | n > 0 = x : genericTake (n-1) xs
+genericTake _ _ = error "List.genericTake: negative argument"
--- partition takes a predicate and a list and returns a pair of lists:
--- those elements of the argument list that do and do not satisfy the
--- predicate, respectively; i,e,,
--- partition p xs == (filter p xs, filter (not . p) xs).
-partition :: (a -> Bool) -> [a] -> ([a],[a])
-partition p xs = foldr select ([],[]) xs
- where select x (ts,fs) | p x = (x:ts,fs)
- | otherwise = (ts, x:fs)
+genericDrop :: (Integral i) => i -> [a] -> [a]
+genericDrop 0 xs = xs
+genericDrop _ [] = []
+genericDrop n (_:xs) | n > 0 = genericDrop (n-1) xs
+genericDrop _ _ = error "List.genericDrop: negative argument"
--- sums and products give a list of running sums or products from
--- a list of numbers. e.g., sums [1,2,3] == [0,1,3,6]
-sums, products :: (Num a) => [a] -> [a]
-sums = scanl (+) 0
-products = scanl (*) 1
+genericSplitAt :: (Integral i) => i -> [b] -> ([b],[b])
+genericSplitAt 0 xs = ([],xs)
+genericSplitAt _ [] = ([],[])
+genericSplitAt n (x:xs) | n > 0 = (x:xs',xs'') where
+ (xs',xs'') = genericSplitAt (n-1) xs
+genericSplitAt _ _ = error "List.genericSplitAt: negative argument"
-transpose :: [[a]] -> [[a]]
-transpose = foldr
- (\xs xss -> zipWith (:) xs (xss ++ repeat []))
- []
+
+genericIndex :: (Integral a) => [b] -> a -> b
+genericIndex (x:_) 0 = x
+genericIndex (_:xs) n
+ | n > 0 = genericIndex xs (n-1)
+ | otherwise = error "List.genericIndex: negative argument."
+genericIndex _ _ = error "List.genericIndex: index too large."
zip4 :: [a] -> [b] -> [c] -> [d] -> [(a,b,c,d)]
zip4 = zipWith4 (,,,)
(a:as,b:bs,c:cs,d:ds,e:es,f:fs,g:gs))
([],[],[],[],[],[],[])
-genericLength :: (Num i) => [b] -> i
-genericLength [] = 0
-genericLength (_:l) = 1 + genericLength l
-genericDrop :: (Integral i) => i -> [a] -> [a]
-genericDrop 0 xs = xs
-genericDrop _ [] = []
-genericDrop n (_:xs) | n > 0 = genericDrop (n-1) xs
-genericDrop _ _ = error "List.genericDrop: negative argument"
-genericTake :: (Integral i) => i -> [a] -> [a]
-genericTake 0 _ = []
-genericTake _ [] = []
-genericTake n (x:xs) | n > 0 = x : genericTake (n-1) xs
-genericTake _ _ = error "List.genericTake: negative argument"
+deleteFirstsBy :: (a -> a -> Bool) -> [a] -> [a] -> [a]
+deleteFirstsBy eq = foldl (flip (deleteBy eq))
-genericSplitAt :: (Integral i) => i -> [b] -> ([b],[b])
-genericSplitAt 0 xs = ([],xs)
-genericSplitAt _ [] = ([],[])
-genericSplitAt n (x:xs) | n > 0 = (x:xs',xs'') where
- (xs',xs'') = genericSplitAt (n-1) xs
-genericSplitAt _ _ = error "List.genericSplitAt: negative argument"
+-- elem, notElem, lookup, maximumBy and minimumBy are in PreludeList
+elemBy, notElemBy :: (a -> a -> Bool) -> a -> [a] -> Bool
+elemBy eq _ [] = False
+elemBy eq x (y:ys) = x `eq` y || elemBy eq x ys
+
+notElemBy eq x xs = not (elemBy eq x xs)
+
+lookupBy :: (a -> a -> Bool) -> a -> [(a, b)] -> Maybe b
+lookupBy eq key [] = Nothing
+lookupBy eq key ((x,y):xys)
+ | key `eq` x = Just y
+ | otherwise = lookupBy eq key xys
+
+
+-- sums and products give a list of running sums or products from
+-- a list of numbers. e.g., sums [1,2,3] == [0,1,3,6]
+sums, products :: (Num a) => [a] -> [a]
+sums = scanl (+) 0
+products = scanl (*) 1
genericReplicate :: (Integral i) => i -> a -> [a]
genericReplicate n x = genericTake n (repeat x)
--- l !! (elemIndex l x) == x if x `elem` l
-elemIndex :: Eq a => [a] -> a -> Int
-elemIndex = elemIndexBy (==)
-
+{-
elemIndexBy :: (a -> a -> Bool) -> [a] -> a -> Int
elemIndexBy eq [] x = error "List.elemIndexBy: empty list"
elemIndexBy eq (x:xs) x' = if x `eq` x' then 0 else 1 + elemIndexBy eq xs x'
groupBy eq [] = []
groupBy eq (x:xs) = (x:ys) : groupBy eq zs
where (ys,zs) = span (eq x) xs
-
-
-mapAccumL :: (a -> b -> (a, c)) -> a -> [b] -> (a, [c])
-mapAccumL f s [] = (s, [])
-mapAccumL f s (x:xs) = (s'',y:ys)
- where (s', y ) = f s x
- (s'',ys) = mapAccumL f s' xs
-
-mapAccumR :: (a -> b -> (a, c)) -> a -> [b] -> (a, [c])
-mapAccumR f s [] = (s, [])
-mapAccumR f s (x:xs) = (s'', y:ys)
- where (s'',y ) = f s' x
- (s', ys) = mapAccumR f s xs
-
--- intersperse sep inserts sep between the elements of its list argument.
--- e.g. intersperse ',' "abcde" == "a,b,c,d,e"
-intersperse :: a -> [a] -> [a]
-intersperse sep [] = []
-intersperse sep [x] = [x]
-intersperse sep (x:xs) = x : sep : intersperse sep xs
-- inits xs returns the list of initial segments of xs, shortest first.
-- e.g., inits "abc" == ["","a","ab","abc"]
where interleave :: a -> [a] -> [[a]]
interleave x [] = [[x]]
interleave x (y:ys) = [x:y:ys] ++ map (y:) (interleave x ys)
-
-union :: (Eq a) => [a] -> [a] -> [a]
-union xs ys = xs ++ (ys \\ xs)
-
-intersect :: (Eq a) => [a] -> [a] -> [a]
-intersect xs ys = [x | x <- xs, x `elem` ys]
+-}
\end{code}
projects / ghc-hetmet.git / blobdiff