{-# LANGUAGE CPP, TupleSections, ConstraintKinds #-}
{-# OPTIONS_GHC -fno-warn-duplicate-exports #-}

-- | This module extends "Data.List" with extra functions of a similar nature.
--   The package also exports the existing "Data.List" functions.
--   Some of the names and semantics were inspired by the
--   <https://hackage.haskell.org/package/text text> package.
module Data.List.Extra(
    module Data.List,
    -- * String operations
    lower, upper, trim, trimStart, trimEnd, word1, line1,
    escapeHTML, escapeJSON,
    unescapeHTML, unescapeJSON,
    -- * Splitting
    dropEnd, takeEnd, splitAtEnd, breakEnd, spanEnd,
    dropWhileEnd', takeWhileEnd,
    stripSuffix, stripInfix, stripInfixEnd,
    dropPrefix, dropSuffix,
    wordsBy, linesBy,
    breakOn, breakOnEnd, splitOn, split, chunksOf,
    -- * Basics
    headDef, lastDef, (!?), notNull, list, unsnoc, cons, snoc,
    drop1, dropEnd1, mconcatMap, compareLength, comparingLength,
    -- * Enum operations
    enumerate,
    -- * List operations
    groupSort, groupSortOn, groupSortBy,
    nubOrd, nubOrdBy, nubOrdOn,
    nubOn, groupOn, groupOnKey,
    nubSort, nubSortBy, nubSortOn,
    maximumOn, minimumOn,
    sum', product',
    sumOn', productOn',
    disjoint, disjointOrd, disjointOrdBy, allSame, anySame,
    repeatedly, repeatedlyNE, firstJust,
    concatUnzip, concatUnzip3,
    zipFrom, zipWithFrom, zipWithLongest,
    replace, merge, mergeBy,
    ) where

import Partial
import Data.List
import Data.Maybe
import Data.Function
import Data.Char
import Data.Tuple.Extra
import Data.Monoid
import Numeric
import Data.Functor
import Data.Foldable
import Prelude
import Data.List.NonEmpty (NonEmpty ((:|)))


-- | Apply some operation repeatedly, producing an element of output
--   and the remainder of the list.
--
-- When the empty list is reached it is returned, so the operation
-- is /never/ applied to the empty input.
-- That fact is encoded in the type system with 'repeatedlyNE'
--
-- > \xs -> repeatedly (splitAt 3) xs  == chunksOf 3 xs
-- > \xs -> repeatedly word1 (trim xs) == words xs
-- > \xs -> repeatedly line1 xs == lines xs
repeatedly :: ([a] -> (b, [a])) -> [a] -> [b]
repeatedly :: forall a b. ([a] -> (b, [a])) -> [a] -> [b]
repeatedly [a] -> (b, [a])
f [] = []
repeatedly [a] -> (b, [a])
f [a]
as = b
b forall a. a -> [a] -> [a]
: forall a b. ([a] -> (b, [a])) -> [a] -> [b]
repeatedly [a] -> (b, [a])
f [a]
as'
    where (b
b, [a]
as') = [a] -> (b, [a])
f [a]
as

-- | Apply some operation repeatedly, producing an element of output
--   and the remainder of the list.
--
-- Identical to 'repeatedly', but has a more precise type signature.
repeatedlyNE :: (NonEmpty a -> (b, [a])) -> [a] -> [b]
repeatedlyNE :: forall a b. (NonEmpty a -> (b, [a])) -> [a] -> [b]
repeatedlyNE NonEmpty a -> (b, [a])
f [] = []
repeatedlyNE NonEmpty a -> (b, [a])
f (a
a : [a]
as) = b
b forall a. a -> [a] -> [a]
: forall a b. (NonEmpty a -> (b, [a])) -> [a] -> [b]
repeatedlyNE NonEmpty a -> (b, [a])
f [a]
as'
    where (b
b, [a]
as') = NonEmpty a -> (b, [a])
f (a
a forall a. a -> [a] -> NonEmpty a
:| [a]
as)



-- | Are two lists disjoint, with no elements in common.
--
-- > disjoint [1,2,3] [4,5] == True
-- > disjoint [1,2,3] [4,1] == False
disjoint :: Eq a => [a] -> [a] -> Bool
disjoint :: forall a. Eq a => [a] -> [a] -> Bool
disjoint [a]
xs = forall (t :: * -> *) a. Foldable t => t a -> Bool
null forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a. Eq a => [a] -> [a] -> [a]
intersect [a]
xs

-- | /O((m+n) log m), m <= n/. Are two lists disjoint, with no elements in common.
--
-- @disjointOrd@ is more strict than `disjoint`. For example, @disjointOrd@ cannot
-- terminate if both lists are infinite, while `disjoint` can.
--
-- > disjointOrd [1,2,3] [4,5] == True
-- > disjointOrd [1,2,3] [4,1] == False
disjointOrd :: Ord a => [a] -> [a] -> Bool
disjointOrd :: forall a. Ord a => [a] -> [a] -> Bool
disjointOrd = forall a. (a -> a -> Ordering) -> [a] -> [a] -> Bool
disjointOrdBy forall a. Ord a => a -> a -> Ordering
compare

-- | A version of 'disjointOrd' with a custom predicate.
--
-- > disjointOrdBy (compare `on` (`mod` 7)) [1,2,3] [4,5] == True
-- > disjointOrdBy (compare `on` (`mod` 7)) [1,2,3] [4,8] == False
disjointOrdBy :: (a -> a -> Ordering) -> [a] -> [a] -> Bool
disjointOrdBy :: forall a. (a -> a -> Ordering) -> [a] -> [a] -> Bool
disjointOrdBy a -> a -> Ordering
cmp [a]
xs [a]
ys
    | forall {a} {a}. [a] -> [a] -> Bool
shorter [a]
xs [a]
ys = forall {t :: * -> *} {t :: * -> *}.
(Foldable t, Foldable t) =>
t a -> t a -> Bool
go [a]
xs [a]
ys
    | Bool
otherwise = forall {t :: * -> *} {t :: * -> *}.
(Foldable t, Foldable t) =>
t a -> t a -> Bool
go [a]
ys [a]
xs
  where
    shorter :: [a] -> [a] -> Bool
shorter [a]
_ [] = Bool
False
    shorter [] [a]
_ = Bool
True
    shorter (a
_:[a]
xs) (a
_:[a]
ys) = [a] -> [a] -> Bool
shorter [a]
xs [a]
ys

    go :: t a -> t a -> Bool
go t a
xs = Bool -> Bool
not forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
any (\a
a -> forall a. (a -> a -> Ordering) -> a -> RB a -> Bool
memberRB a -> a -> Ordering
cmp a
a RB a
tree)
      where
        tree :: RB a
tree = forall (t :: * -> *) b a.
Foldable t =>
(b -> a -> b) -> b -> t a -> b
foldl' (forall a b c. (a -> b -> c) -> b -> a -> c
flip (forall a. (a -> a -> Ordering) -> a -> RB a -> RB a
insertRB a -> a -> Ordering
cmp)) forall a. RB a
E t a
xs

-- | Is there any element which occurs more than once.
--
-- > anySame [1,1,2] == True
-- > anySame [1,2,3] == False
-- > anySame (1:2:1:undefined) == True
-- > anySame [] == False
-- > \xs -> anySame xs == (length (nub xs) < length xs)
anySame :: Eq a => [a] -> Bool
anySame :: forall a. Eq a => [a] -> Bool
anySame = forall a. Eq a => [a] -> [a] -> Bool
f []
    where
        f :: [a] -> [a] -> Bool
f [a]
seen (a
x:[a]
xs) = a
x forall (t :: * -> *) a. (Foldable t, Eq a) => a -> t a -> Bool
`elem` [a]
seen Bool -> Bool -> Bool
|| [a] -> [a] -> Bool
f (a
xforall a. a -> [a] -> [a]
:[a]
seen) [a]
xs
        f [a]
seen [] = Bool
False

-- | Are all elements the same.
--
-- > allSame [1,1,2] == False
-- > allSame [1,1,1] == True
-- > allSame [1]     == True
-- > allSame []      == True
-- > allSame (1:1:2:undefined) == False
-- > \xs -> allSame xs == (length (nub xs) <= 1)
allSame :: Eq a => [a] -> Bool
allSame :: forall a. Eq a => [a] -> Bool
allSame [] = Bool
True
allSame (a
x:[a]
xs) = forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
all (a
x forall a. Eq a => a -> a -> Bool
==) [a]
xs


-- | A total 'head' with a default value.
--
-- > headDef 1 []      == 1
-- > headDef 1 [2,3,4] == 2
-- > \x xs -> headDef x xs == fromMaybe x (listToMaybe xs)
headDef :: a -> [a] -> a
headDef :: forall a. a -> [a] -> a
headDef a
d [] = a
d
headDef a
_ (a
x:[a]
_) = a
x


-- | A total 'last' with a default value.
--
-- > lastDef 1 []      == 1
-- > lastDef 1 [2,3,4] == 4
-- > \x xs -> lastDef x xs == last (x:xs)
lastDef :: a -> [a] -> a
lastDef :: forall a. a -> [a] -> a
lastDef a
d [a]
xs = forall (t :: * -> *) b a.
Foldable t =>
(b -> a -> b) -> b -> t a -> b
foldl (\a
_ a
x -> a
x) a
d [a]
xs -- I know this looks weird, but apparently this is the fastest way to do this: https://hackage.haskell.org/package/base-4.12.0.0/docs/src/GHC.List.html#last
{-# INLINE lastDef #-}

#if __GLASGOW_HASKELL__ <= 906
-- | A total variant of the list index function `(!!)`.
--
-- > [2,3,4] !? 1    == Just 3
-- > [2,3,4] !? (-1) == Nothing
-- > []      !? 0    == Nothing
(!?) :: [a] -> Int -> Maybe a
[a]
xs !? :: forall a. [a] -> Int -> Maybe a
!? Int
n
  | Int
n forall a. Ord a => a -> a -> Bool
< Int
0     = forall a. Maybe a
Nothing
             -- Definition adapted from GHC.List
  | Bool
otherwise = forall (t :: * -> *) a b.
Foldable t =>
(a -> b -> b) -> b -> t a -> b
foldr (\a
x Int -> Maybe a
r Int
k -> case Int
k of
                                   Int
0 -> forall a. a -> Maybe a
Just a
x
                                   Int
_ -> Int -> Maybe a
r (Int
kforall a. Num a => a -> a -> a
-Int
1)) (forall a b. a -> b -> a
const forall a. Maybe a
Nothing) [a]
xs Int
n
{-# INLINABLE (!?) #-}
#endif

-- | A composition of 'not' and 'null'.
--
-- > notNull []  == False
-- > notNull [1] == True
-- > \xs -> notNull xs == not (null xs)
notNull :: [a] -> Bool
notNull :: forall a. [a] -> Bool
notNull = Bool -> Bool
not forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall (t :: * -> *) a. Foldable t => t a -> Bool
null

-- | Non-recursive transform over a list, like 'maybe'.
--
-- > list 1 (\v _ -> v - 2) [5,6,7] == 3
-- > list 1 (\v _ -> v - 2) []      == 1
-- > \nil cons xs -> maybe nil (uncurry cons) (uncons xs) == list nil cons xs
list :: b -> (a -> [a] -> b) -> [a] -> b
list :: forall b a. b -> (a -> [a] -> b) -> [a] -> b
list b
nil a -> [a] -> b
cons [] = b
nil
list b
nil a -> [a] -> b
cons (a
x:[a]
xs) = a -> [a] -> b
cons a
x [a]
xs

#if __GLASGOW_HASKELL__ <= 906
-- | If the list is empty returns 'Nothing', otherwise returns the 'init' and the 'last'.
--
-- > unsnoc "test" == Just ("tes",'t')
-- > unsnoc ""     == Nothing
-- > \xs -> unsnoc xs == if null xs then Nothing else Just (init xs, last xs)
unsnoc :: [a] -> Maybe ([a], a)
unsnoc :: forall a. [a] -> Maybe ([a], a)
unsnoc [] = forall a. Maybe a
Nothing
unsnoc [a
x] = forall a. a -> Maybe a
Just ([], a
x)
unsnoc (a
x:[a]
xs) = forall a. a -> Maybe a
Just (a
xforall a. a -> [a] -> [a]
:[a]
a, a
b)
    where Just ([a]
a,a
b) = forall a. [a] -> Maybe ([a], a)
unsnoc [a]
xs
#endif

-- | Append an element to the start of a list, an alias for '(:)'.
--
-- > cons 't' "est" == "test"
-- > \x xs -> uncons (cons x xs) == Just (x,xs)
cons :: a -> [a] -> [a]
cons :: forall a. a -> [a] -> [a]
cons = (:)

-- | Append an element to the end of a list, takes /O(n)/ time.
--
-- > snoc "tes" 't' == "test"
-- > \xs x -> unsnoc (snoc xs x) == Just (xs,x)
snoc :: [a] -> a -> [a]
snoc :: forall a. [a] -> a -> [a]
snoc [a]
xs a
x = [a]
xs forall a. [a] -> [a] -> [a]
++ [a
x]


-- | Enumerate all the values of an 'Enum', from 'minBound' to 'maxBound'.
--
-- > enumerate == [False, True]
enumerate :: (Enum a, Bounded a) => [a]
enumerate :: forall a. (Enum a, Bounded a) => [a]
enumerate = [forall a. Bounded a => a
minBound..forall a. Bounded a => a
maxBound]

-- | Take a number of elements from the end of the list.
--
-- > takeEnd 3 "hello"  == "llo"
-- > takeEnd 5 "bye"    == "bye"
-- > takeEnd (-1) "bye" == ""
-- > \i xs -> takeEnd i xs `isSuffixOf` xs
-- > \i xs -> length (takeEnd i xs) == min (max 0 i) (length xs)
takeEnd :: Int -> [a] -> [a]
takeEnd :: forall a. Int -> [a] -> [a]
takeEnd Int
i [a]
xs
    | Int
i forall a. Ord a => a -> a -> Bool
<= Int
0 = []
    | Bool
otherwise = forall {a} {a}. [a] -> [a] -> [a]
f [a]
xs (forall a. Int -> [a] -> [a]
drop Int
i [a]
xs)
    where f :: [a] -> [a] -> [a]
f (a
x:[a]
xs) (a
y:[a]
ys) = [a] -> [a] -> [a]
f [a]
xs [a]
ys
          f [a]
xs [a]
_ = [a]
xs

-- | Drop a number of elements from the end of the list.
--
-- > dropEnd 3 "hello"  == "he"
-- > dropEnd 5 "bye"    == ""
-- > dropEnd (-1) "bye" == "bye"
-- > \i xs -> dropEnd i xs `isPrefixOf` xs
-- > \i xs -> length (dropEnd i xs) == max 0 (length xs - max 0 i)
-- > \i -> take 3 (dropEnd 5 [i..]) == take 3 [i..]
dropEnd :: Int -> [a] -> [a]
dropEnd :: forall a. Int -> [a] -> [a]
dropEnd Int
i [a]
xs
    | Int
i forall a. Ord a => a -> a -> Bool
<= Int
0 = [a]
xs
    | Bool
otherwise = forall {a} {a}. [a] -> [a] -> [a]
f [a]
xs (forall a. Int -> [a] -> [a]
drop Int
i [a]
xs)
    where f :: [a] -> [a] -> [a]
f (a
x:[a]
xs) (a
y:[a]
ys) = a
x forall a. a -> [a] -> [a]
: [a] -> [a] -> [a]
f [a]
xs [a]
ys
          f [a]
_ [a]
_ = []


-- | @'splitAtEnd' n xs@ returns a split where the second element tries to
--   contain @n@ elements.
--
-- > splitAtEnd 3 "hello" == ("he","llo")
-- > splitAtEnd 3 "he"    == ("", "he")
-- > \i xs -> uncurry (++) (splitAt i xs) == xs
-- > \i xs -> splitAtEnd i xs == (dropEnd i xs, takeEnd i xs)
splitAtEnd :: Int -> [a] -> ([a], [a])
splitAtEnd :: forall a. Int -> [a] -> ([a], [a])
splitAtEnd Int
i [a]
xs
    | Int
i forall a. Ord a => a -> a -> Bool
<= Int
0 = ([a]
xs, [])
    | Bool
otherwise = forall {a} {a}. [a] -> [a] -> ([a], [a])
f [a]
xs (forall a. Int -> [a] -> [a]
drop Int
i [a]
xs)
    where f :: [a] -> [a] -> ([a], [a])
f (a
x:[a]
xs) (a
y:[a]
ys) = forall a a' b. (a -> a') -> (a, b) -> (a', b)
first (a
xforall a. a -> [a] -> [a]
:) forall a b. (a -> b) -> a -> b
$ [a] -> [a] -> ([a], [a])
f [a]
xs [a]
ys
          f [a]
xs [a]
_ = ([], [a]
xs)


-- | 'zip' against an enumeration.
--   Truncates the output if the enumeration runs out.
--
-- > \i xs -> zip [i..] xs == zipFrom i xs
-- > zipFrom False [1..3] == [(False,1),(True, 2)]
zipFrom :: Enum a => a -> [b] -> [(a, b)]
zipFrom :: forall a b. Enum a => a -> [b] -> [(a, b)]
zipFrom = forall a b c. Enum a => (a -> b -> c) -> a -> [b] -> [c]
zipWithFrom (,)

-- | 'zipFrom' generalised to any combining operation.
--   Truncates the output if the enumeration runs out.
--
-- > \i xs -> zipWithFrom (,) i xs == zipFrom i xs
zipWithFrom :: Enum a => (a -> b -> c) -> a -> [b] -> [c]
-- would love to deforest the intermediate [a..] list
-- but would require Bounded and Eq as well, so better go for simplicit
zipWithFrom :: forall a b c. Enum a => (a -> b -> c) -> a -> [b] -> [c]
zipWithFrom a -> b -> c
f a
a = forall a b c. (a -> b -> c) -> [a] -> [b] -> [c]
zipWith a -> b -> c
f [a
a..]


-- | A merging of 'unzip' and 'concat'.
--
-- > concatUnzip [("a","AB"),("bc","C")] == ("abc","ABC")
concatUnzip :: [([a], [b])] -> ([a], [b])
concatUnzip :: forall a b. [([a], [b])] -> ([a], [b])
concatUnzip = (forall (t :: * -> *) a. Foldable t => t [a] -> [a]
concat forall a a' b b'. (a -> a') -> (b -> b') -> (a, b) -> (a', b')
*** forall (t :: * -> *) a. Foldable t => t [a] -> [a]
concat) forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a b. [(a, b)] -> ([a], [b])
Prelude.unzip

-- | A merging of 'unzip3' and 'concat'.
--
-- > concatUnzip3 [("a","AB",""),("bc","C","123")] == ("abc","ABC","123")
concatUnzip3 :: [([a],[b],[c])] -> ([a],[b],[c])
concatUnzip3 :: forall a b c. [([a], [b], [c])] -> ([a], [b], [c])
concatUnzip3 [([a], [b], [c])]
xs = (forall (t :: * -> *) a. Foldable t => t [a] -> [a]
concat [[a]]
a, forall (t :: * -> *) a. Foldable t => t [a] -> [a]
concat [[b]]
b, forall (t :: * -> *) a. Foldable t => t [a] -> [a]
concat [[c]]
c)
    where ([[a]]
a,[[b]]
b,[[c]]
c) = forall a b c. [(a, b, c)] -> ([a], [b], [c])
unzip3 [([a], [b], [c])]
xs


-- | A version of 'takeWhile' operating from the end.
--
-- > takeWhileEnd even [2,3,4,6] == [4,6]
takeWhileEnd :: (a -> Bool) -> [a] -> [a]
takeWhileEnd :: forall a. (a -> Bool) -> [a] -> [a]
takeWhileEnd a -> Bool
f = forall a. [a] -> [a]
reverse forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a. (a -> Bool) -> [a] -> [a]
takeWhile a -> Bool
f forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a. [a] -> [a]
reverse


-- | Remove spaces from the start of a string, see 'trim'.
trimStart :: String -> String
trimStart :: String -> String
trimStart = forall a. (a -> Bool) -> [a] -> [a]
dropWhile Char -> Bool
isSpace

-- | Remove spaces from the end of a string, see 'trim'.
trimEnd :: String -> String
trimEnd :: String -> String
trimEnd = forall a. (a -> Bool) -> [a] -> [a]
dropWhileEnd Char -> Bool
isSpace

-- | Remove spaces from either side of a string. A combination of 'trimEnd' and 'trimStart'.
--
-- > trim      "  hello   " == "hello"
-- > trimStart "  hello   " == "hello   "
-- > trimEnd   "  hello   " == "  hello"
-- > \s -> trim s == trimEnd (trimStart s)
trim :: String -> String
trim :: String -> String
trim = String -> String
trimEnd forall b c a. (b -> c) -> (a -> b) -> a -> c
. String -> String
trimStart

-- | Convert a string to lower case.
--
-- > lower "This is A TEST" == "this is a test"
-- > lower "" == ""
lower :: String -> String
lower :: String -> String
lower = forall a b. (a -> b) -> [a] -> [b]
map Char -> Char
toLower

-- | Convert a string to upper case.
--
-- > upper "This is A TEST" == "THIS IS A TEST"
-- > upper "" == ""
upper :: String -> String
upper :: String -> String
upper = forall a b. (a -> b) -> [a] -> [b]
map Char -> Char
toUpper


-- | Split the first word off a string. Useful for when starting to parse the beginning
--   of a string, but you want to accurately preserve whitespace in the rest of the string.
--
-- > word1 "" == ("", "")
-- > word1 "keyword rest of string" == ("keyword","rest of string")
-- > word1 "  keyword\n  rest of string" == ("keyword","rest of string")
-- > \s -> fst (word1 s) == concat (take 1 $ words s)
-- > \s -> words (snd $ word1 s) == drop 1 (words s)
word1 :: String -> (String, String)
word1 :: String -> (String, String)
word1 = forall b b' a. (b -> b') -> (a, b) -> (a, b')
second String -> String
trimStart forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a. (a -> Bool) -> [a] -> ([a], [a])
break Char -> Bool
isSpace forall b c a. (b -> c) -> (a -> b) -> a -> c
. String -> String
trimStart

-- | Split the first line off a string.
--
-- > line1 "" == ("", "")
-- > line1 "test" == ("test","")
-- > line1 "test\n" == ("test","")
-- > line1 "test\nrest" == ("test","rest")
-- > line1 "test\nrest\nmore" == ("test","rest\nmore")
line1 :: String -> (String, String)
line1 :: String -> (String, String)
line1 = forall b b' a. (b -> b') -> (a, b) -> (a, b')
second forall a. [a] -> [a]
drop1 forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a. (a -> Bool) -> [a] -> ([a], [a])
break (forall a. Eq a => a -> a -> Bool
== Char
'\n')

-- | Escape a string such that it can be inserted into an HTML document or @\"@ attribute
--   without any special interpretation. This requires escaping the @<@, @>@, @&@ and @\"@ characters.
--   Note that it will escape @\"@ and @\'@ even though that is not required in an HTML body (but is not harmful).
--
-- > escapeHTML "this is a test" == "this is a test"
-- > escapeHTML "<b>\"g&t\"</n>" == "&lt;b&gt;&quot;g&amp;t&quot;&lt;/n&gt;"
-- > escapeHTML "t'was another test" == "t&#39;was another test"
escapeHTML :: String -> String
escapeHTML :: String -> String
escapeHTML = forall (t :: * -> *) a b. Foldable t => (a -> [b]) -> t a -> [b]
concatMap Char -> String
f
    where
        f :: Char -> String
f Char
'>' = String
"&gt;"
        f Char
'<' = String
"&lt;"
        f Char
'&' = String
"&amp;"
        f Char
'\"' = String
"&quot;"
        f Char
'\'' = String
"&#39;"
        f Char
x = [Char
x]

-- | Invert of 'escapeHTML' (does not do general HTML unescaping)
--
-- > \xs -> unescapeHTML (escapeHTML xs) == xs
unescapeHTML :: String -> String
unescapeHTML :: String -> String
unescapeHTML (Char
'&':String
xs)
    | Just String
xs <- forall a. Eq a => [a] -> [a] -> Maybe [a]
stripPrefix String
"lt;" String
xs = Char
'<' forall a. a -> [a] -> [a]
: String -> String
unescapeHTML String
xs
    | Just String
xs <- forall a. Eq a => [a] -> [a] -> Maybe [a]
stripPrefix String
"gt;" String
xs = Char
'>' forall a. a -> [a] -> [a]
: String -> String
unescapeHTML String
xs
    | Just String
xs <- forall a. Eq a => [a] -> [a] -> Maybe [a]
stripPrefix String
"amp;" String
xs = Char
'&' forall a. a -> [a] -> [a]
: String -> String
unescapeHTML String
xs
    | Just String
xs <- forall a. Eq a => [a] -> [a] -> Maybe [a]
stripPrefix String
"quot;" String
xs = Char
'\"' forall a. a -> [a] -> [a]
: String -> String
unescapeHTML String
xs
    | Just String
xs <- forall a. Eq a => [a] -> [a] -> Maybe [a]
stripPrefix String
"#39;" String
xs = Char
'\'' forall a. a -> [a] -> [a]
: String -> String
unescapeHTML String
xs
unescapeHTML (Char
x:String
xs) = Char
x forall a. a -> [a] -> [a]
: String -> String
unescapeHTML String
xs
unescapeHTML [] = []


-- | Escape a string so it can form part of a JSON literal.
--   This requires escaping the special whitespace and control characters. Additionally,
--   Note that it does /not/ add quote characters around the string.
--
-- > escapeJSON "this is a test" == "this is a test"
-- > escapeJSON "\ttab\nnewline\\" == "\\ttab\\nnewline\\\\"
-- > escapeJSON "\ESC[0mHello" == "\\u001b[0mHello"
escapeJSON :: String -> String
escapeJSON :: String -> String
escapeJSON String
x = forall (t :: * -> *) a b. Foldable t => (a -> [b]) -> t a -> [b]
concatMap Char -> String
f String
x
    where f :: Char -> String
f Char
'\"' = String
"\\\""
          f Char
'\\' = String
"\\\\"
          -- the spaces are technically optional, but we include them so the JSON is readable
          f Char
'\b' = String
"\\b"
          f Char
'\f' = String
"\\f"
          f Char
'\n' = String
"\\n"
          f Char
'\r' = String
"\\r"
          f Char
'\t' = String
"\\t"
          f Char
x | Char -> Bool
isControl Char
x = String
"\\u" forall a. [a] -> [a] -> [a]
++ forall a. Int -> [a] -> [a]
takeEnd Int
4 (String
"0000" forall a. [a] -> [a] -> [a]
++ forall a. (Integral a, Show a) => a -> String -> String
showHex (Char -> Int
ord Char
x) String
"")
          f Char
x = [Char
x]

-- | General JSON unescaping, inversion of 'escapeJSON' and all other JSON escapes.
--
-- > \xs -> unescapeJSON (escapeJSON xs) == xs
unescapeJSON :: String -> String
unescapeJSON :: String -> String
unescapeJSON (Char
'\\':Char
x:String
xs)
    | Char
x forall a. Eq a => a -> a -> Bool
== Char
'\"' = Char
'\"' forall a. a -> [a] -> [a]
: String -> String
unescapeJSON String
xs
    | Char
x forall a. Eq a => a -> a -> Bool
== Char
'\\' = Char
'\\' forall a. a -> [a] -> [a]
: String -> String
unescapeJSON String
xs
    | Char
x forall a. Eq a => a -> a -> Bool
== Char
'/' = Char
'/' forall a. a -> [a] -> [a]
: String -> String
unescapeJSON String
xs
    | Char
x forall a. Eq a => a -> a -> Bool
== Char
'b' = Char
'\b' forall a. a -> [a] -> [a]
: String -> String
unescapeJSON String
xs
    | Char
x forall a. Eq a => a -> a -> Bool
== Char
'f' = Char
'\f' forall a. a -> [a] -> [a]
: String -> String
unescapeJSON String
xs
    | Char
x forall a. Eq a => a -> a -> Bool
== Char
'n' = Char
'\n' forall a. a -> [a] -> [a]
: String -> String
unescapeJSON String
xs
    | Char
x forall a. Eq a => a -> a -> Bool
== Char
'r' = Char
'\r' forall a. a -> [a] -> [a]
: String -> String
unescapeJSON String
xs
    | Char
x forall a. Eq a => a -> a -> Bool
== Char
't' = Char
'\t' forall a. a -> [a] -> [a]
: String -> String
unescapeJSON String
xs
    | Char
x forall a. Eq a => a -> a -> Bool
== Char
'u', let (String
a,String
b) = forall a. Int -> [a] -> ([a], [a])
splitAt Int
4 String
xs, forall (t :: * -> *) a. Foldable t => t a -> Int
length String
a forall a. Eq a => a -> a -> Bool
== Int
4, [(Int
i, String
"")] <- forall a. (Eq a, Num a) => ReadS a
readHex String
a = Int -> Char
chr Int
i forall a. a -> [a] -> [a]
: String -> String
unescapeJSON String
b
unescapeJSON (Char
x:String
xs) = Char
x forall a. a -> [a] -> [a]
: String -> String
unescapeJSON String
xs
unescapeJSON [] = []


-- | A version of 'group' where the equality is done on some extracted value.
--
-- > groupOn abs [1,-1,2] == [[1,-1], [2]]
groupOn :: Eq k => (a -> k) -> [a] -> [[a]]
groupOn :: forall k a. Eq k => (a -> k) -> [a] -> [[a]]
groupOn a -> k
f = forall a. (a -> a -> Bool) -> [a] -> [[a]]
groupBy (forall a. Eq a => a -> a -> Bool
(==) forall {t} {t} {p}. (t -> t -> t) -> (p -> t) -> p -> p -> t
`on2` a -> k
f)
    -- redefine on so we avoid duplicate computation for most values.
    where t -> t -> t
(.*.) on2 :: (t -> t -> t) -> (p -> t) -> p -> p -> t
`on2` p -> t
f = \p
x -> let fx :: t
fx = p -> t
f p
x in \p
y -> t
fx t -> t -> t
.*. p -> t
f p
y


-- | A version of 'groupOn' which pairs each group with its "key" - the
--   extracted value used for equality testing.
--
-- > groupOnKey abs [1,-1,2] == [(1, [1,-1]), (2, [2])]
groupOnKey :: Eq k => (a -> k) -> [a] -> [(k, [a])]
groupOnKey :: forall k a. Eq k => (a -> k) -> [a] -> [(k, [a])]
groupOnKey a -> k
_ []     = []
groupOnKey a -> k
f (a
x:[a]
xs) = (k
fx, a
xforall a. a -> [a] -> [a]
:[a]
yes) forall a. a -> [a] -> [a]
: forall k a. Eq k => (a -> k) -> [a] -> [(k, [a])]
groupOnKey a -> k
f [a]
no
    where
        fx :: k
fx = a -> k
f a
x
        ([a]
yes, [a]
no) = forall a. (a -> Bool) -> [a] -> ([a], [a])
span (\a
y -> k
fx forall a. Eq a => a -> a -> Bool
== a -> k
f a
y) [a]
xs


-- | /DEPRECATED/ Use 'nubOrdOn', since this function is _O(n^2)_.
--
--   A version of 'nub' where the equality is done on some extracted value.
--   @nubOn f@ is equivalent to @nubBy ((==) `on` f)@, but has the
--   performance advantage of only evaluating @f@ once for each element in the
--   input list.
{-# DEPRECATED nubOn "Use nubOrdOn, since this function is O(n^2)" #-}
nubOn :: Eq b => (a -> b) -> [a] -> [a]
nubOn :: forall b a. Eq b => (a -> b) -> [a] -> [a]
nubOn a -> b
f = forall a b. (a -> b) -> [a] -> [b]
map forall a b. (a, b) -> b
snd forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a. (a -> a -> Bool) -> [a] -> [a]
nubBy (forall a. Eq a => a -> a -> Bool
(==) forall {t} {t} {p}. (t -> t -> t) -> (p -> t) -> p -> p -> t
`on` forall a b. (a, b) -> a
fst) forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a b. (a -> b) -> [a] -> [b]
map (\a
x -> let y :: b
y = a -> b
f a
x in b
y seq :: forall a b. a -> b -> b
`seq` (b
y, a
x))

-- | A version of 'maximum' where the comparison is done on some extracted value.
--   Raises an error if the list is empty. Only calls the function once per element.
--
-- > maximumOn id [] == undefined
-- > maximumOn length ["test","extra","a"] == "extra"
maximumOn :: (Partial, Ord b) => (a -> b) -> [a] -> a
maximumOn :: forall b a. (Partial, Ord b) => (a -> b) -> [a] -> a
maximumOn a -> b
f [] = forall a. Partial => String -> a
error String
"Data.List.Extra.maximumOn: empty list"
maximumOn a -> b
f (a
x:[a]
xs) = a -> b -> [a] -> a
g a
x (a -> b
f a
x) [a]
xs
    where
        g :: a -> b -> [a] -> a
g a
v b
mv [] = a
v
        g a
v b
mv (a
x:[a]
xs) | b
mx forall a. Ord a => a -> a -> Bool
> b
mv = a -> b -> [a] -> a
g a
x b
mx [a]
xs
                      | Bool
otherwise = a -> b -> [a] -> a
g a
v b
mv [a]
xs
            where mx :: b
mx = a -> b
f a
x


-- | A version of 'minimum' where the comparison is done on some extracted value.
--   Raises an error if the list is empty. Only calls the function once per element.
--
-- > minimumOn id [] == undefined
-- > minimumOn length ["test","extra","a"] == "a"
minimumOn :: (Partial, Ord b) => (a -> b) -> [a] -> a
minimumOn :: forall b a. (Partial, Ord b) => (a -> b) -> [a] -> a
minimumOn a -> b
f [] = forall a. Partial => String -> a
error String
"Data.List.Extra.minimumOn: empty list"
minimumOn a -> b
f (a
x:[a]
xs) = a -> b -> [a] -> a
g a
x (a -> b
f a
x) [a]
xs
    where
        g :: a -> b -> [a] -> a
g a
v b
mv [] = a
v
        g a
v b
mv (a
x:[a]
xs) | b
mx forall a. Ord a => a -> a -> Bool
< b
mv = a -> b -> [a] -> a
g a
x b
mx [a]
xs
                      | Bool
otherwise = a -> b -> [a] -> a
g a
v b
mv [a]
xs
            where mx :: b
mx = a -> b
f a
x

-- | A combination of 'group' and 'sort'.
--
-- > groupSort [(1,'t'),(3,'t'),(2,'e'),(2,'s')] == [(1,"t"),(2,"es"),(3,"t")]
-- > \xs -> map fst (groupSort xs) == sort (nub (map fst xs))
-- > \xs -> concatMap snd (groupSort xs) == map snd (sortOn fst xs)
groupSort :: Ord k => [(k, v)] -> [(k, [v])]
groupSort :: forall k v. Ord k => [(k, v)] -> [(k, [v])]
groupSort = forall a b. (a -> b) -> [a] -> [b]
map (\[(k, v)]
x -> (forall a b. (a, b) -> a
fst forall a b. (a -> b) -> a -> b
$ forall a. [a] -> a
head [(k, v)]
x, forall a b. (a -> b) -> [a] -> [b]
map forall a b. (a, b) -> b
snd [(k, v)]
x)) forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall k a. Eq k => (a -> k) -> [a] -> [[a]]
groupOn forall a b. (a, b) -> a
fst forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall b a. Ord b => (a -> b) -> [a] -> [a]
sortOn forall a b. (a, b) -> a
fst

-- | A combination of 'group' and 'sort', using a part of the value to compare on.
--
-- > groupSortOn length ["test","of","sized","item"] == [["of"],["test","item"],["sized"]]
groupSortOn :: Ord b => (a -> b) -> [a] -> [[a]]
groupSortOn :: forall b a. Ord b => (a -> b) -> [a] -> [[a]]
groupSortOn a -> b
f = forall a b. (a -> b) -> [a] -> [b]
map (forall a b. (a -> b) -> [a] -> [b]
map forall a b. (a, b) -> b
snd) forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a. (a -> a -> Bool) -> [a] -> [[a]]
groupBy (forall a. Eq a => a -> a -> Bool
(==) forall {t} {t} {p}. (t -> t -> t) -> (p -> t) -> p -> p -> t
`on` forall a b. (a, b) -> a
fst) forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a. (a -> a -> Ordering) -> [a] -> [a]
sortBy (forall a. Ord a => a -> a -> Ordering
compare forall {t} {t} {p}. (t -> t -> t) -> (p -> t) -> p -> p -> t
`on` forall a b. (a, b) -> a
fst) forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a b. (a -> b) -> [a] -> [b]
map (a -> b
f forall a b c. (a -> b) -> (a -> c) -> a -> (b, c)
&&& forall a. a -> a
id)

-- | A combination of 'group' and 'sort', using a predicate to compare on.
--
-- > groupSortBy (compare `on` length) ["test","of","sized","item"] == [["of"],["test","item"],["sized"]]
groupSortBy :: (a -> a -> Ordering) -> [a] -> [[a]]
groupSortBy :: forall a. (a -> a -> Ordering) -> [a] -> [[a]]
groupSortBy a -> a -> Ordering
f = forall a. (a -> a -> Bool) -> [a] -> [[a]]
groupBy (\a
a a
b -> a -> a -> Ordering
f a
a a
b forall a. Eq a => a -> a -> Bool
== Ordering
EQ) forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a. (a -> a -> Ordering) -> [a] -> [a]
sortBy a -> a -> Ordering
f


-- | A strict version of 'sum'.
--   Unlike 'sum' this function is always strict in the `Num` argument,
--   whereas the standard version is only strict if the optimiser kicks in.
--
-- > sum' [1, 2, 3] == 6
sum' :: (Num a) => [a] -> a
sum' :: forall a. Num a => [a] -> a
sum' = forall (t :: * -> *) b a.
Foldable t =>
(b -> a -> b) -> b -> t a -> b
foldl' forall a. Num a => a -> a -> a
(+) a
0

-- | A strict version of 'sum', using a custom valuation function.
--
-- > sumOn' read ["1", "2", "3"] == 6
sumOn' :: (Num b) => (a -> b) -> [a] -> b
sumOn' :: forall b a. Num b => (a -> b) -> [a] -> b
sumOn' a -> b
f = forall (t :: * -> *) b a.
Foldable t =>
(b -> a -> b) -> b -> t a -> b
foldl' (\b
acc a
x -> b
acc forall a. Num a => a -> a -> a
+ a -> b
f a
x) b
0

-- | A strict version of 'product'.
--
-- > product' [1, 2, 4] == 8
product' :: (Num a) => [a] -> a
product' :: forall a. Num a => [a] -> a
product' = forall (t :: * -> *) b a.
Foldable t =>
(b -> a -> b) -> b -> t a -> b
foldl' forall a. Num a => a -> a -> a
(*) a
1

-- | A strict version of 'product', using a custom valuation function.
--
-- > productOn' read ["1", "2", "4"] == 8
productOn' :: (Num b) => (a -> b) -> [a] -> b
productOn' :: forall b a. Num b => (a -> b) -> [a] -> b
productOn' a -> b
f = forall (t :: * -> *) b a.
Foldable t =>
(b -> a -> b) -> b -> t a -> b
foldl' (\b
acc a
x -> b
acc forall a. Num a => a -> a -> a
* a -> b
f a
x) b
1

-- | Merge two lists which are assumed to be ordered.
--
-- > merge "ace" "bd" == "abcde"
-- > \xs ys -> merge (sort xs) (sort ys) == sort (xs ++ ys)
merge :: Ord a => [a] -> [a] -> [a]
merge :: forall a. Ord a => [a] -> [a] -> [a]
merge = forall a. (a -> a -> Ordering) -> [a] -> [a] -> [a]
mergeBy forall a. Ord a => a -> a -> Ordering
compare


-- | Like 'merge', but with a custom ordering function.
mergeBy :: (a -> a -> Ordering) -> [a] -> [a] -> [a]
mergeBy :: forall a. (a -> a -> Ordering) -> [a] -> [a] -> [a]
mergeBy a -> a -> Ordering
f [a]
xs [] = [a]
xs
mergeBy a -> a -> Ordering
f [] [a]
ys = [a]
ys
mergeBy a -> a -> Ordering
f (a
x:[a]
xs) (a
y:[a]
ys)
    | a -> a -> Ordering
f a
x a
y forall a. Eq a => a -> a -> Bool
/= Ordering
GT = a
x forall a. a -> [a] -> [a]
: forall a. (a -> a -> Ordering) -> [a] -> [a] -> [a]
mergeBy a -> a -> Ordering
f [a]
xs (a
yforall a. a -> [a] -> [a]
:[a]
ys)
    | Bool
otherwise = a
y forall a. a -> [a] -> [a]
: forall a. (a -> a -> Ordering) -> [a] -> [a] -> [a]
mergeBy a -> a -> Ordering
f (a
xforall a. a -> [a] -> [a]
:[a]
xs) [a]
ys


-- | Replace a subsequence everywhere it occurs.
--
-- > replace "el" "_" "Hello Bella" == "H_lo B_la"
-- > replace "el" "e" "Hello"       == "Helo"
-- > replace "" "x" "Hello"         == "xHxexlxlxox"
-- > replace "" "x" ""              == "x"
-- > \xs ys -> replace xs xs ys == ys
replace :: Eq a => [a] -> [a] -> [a] -> [a]
replace :: forall a. Eq a => [a] -> [a] -> [a] -> [a]
replace [] [a]
to [a]
xs = [a] -> [a]
go [a]
xs
    where go :: [a] -> [a]
go [] = [a]
to
          go (a
x:[a]
xs) = [a]
to forall a. [a] -> [a] -> [a]
++ a
x forall a. a -> [a] -> [a]
: [a] -> [a]
go [a]
xs
replace [a]
from [a]
to [a]
xs | Just [a]
xs <- forall a. Eq a => [a] -> [a] -> Maybe [a]
stripPrefix [a]
from [a]
xs = [a]
to forall a. [a] -> [a] -> [a]
++ forall a. Eq a => [a] -> [a] -> [a] -> [a]
replace [a]
from [a]
to [a]
xs
replace [a]
from [a]
to (a
x:[a]
xs) = a
x forall a. a -> [a] -> [a]
: forall a. Eq a => [a] -> [a] -> [a] -> [a]
replace [a]
from [a]
to [a]
xs
replace [a]
from [a]
to [] = []


-- | Break, but from the end.
--
-- > breakEnd isLower "youRE" == ("you","RE")
-- > breakEnd isLower "youre" == ("youre","")
-- > breakEnd isLower "YOURE" == ("","YOURE")
-- > \f xs -> breakEnd (not . f) xs == spanEnd f  xs
breakEnd :: (a -> Bool) -> [a] -> ([a], [a])
breakEnd :: forall a. (a -> Bool) -> [a] -> ([a], [a])
breakEnd a -> Bool
f = forall a b. (a, b) -> (b, a)
swap forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a b. (a -> b) -> (a, a) -> (b, b)
both forall a. [a] -> [a]
reverse forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a. (a -> Bool) -> [a] -> ([a], [a])
break a -> Bool
f forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a. [a] -> [a]
reverse

-- | Span, but from the end.
--
-- > spanEnd isUpper "youRE" == ("you","RE")
-- > spanEnd (not . isSpace) "x y z" == ("x y ","z")
-- > \f xs -> uncurry (++) (spanEnd f xs) == xs
-- > \f xs -> spanEnd f xs == swap (both reverse (span f (reverse xs)))
spanEnd :: (a -> Bool) -> [a] -> ([a], [a])
spanEnd :: forall a. (a -> Bool) -> [a] -> ([a], [a])
spanEnd a -> Bool
f = forall a. (a -> Bool) -> [a] -> ([a], [a])
breakEnd (Bool -> Bool
not forall b c a. (b -> c) -> (a -> b) -> a -> c
. a -> Bool
f)


-- | A variant of 'words' with a custom test. In particular,
--   adjacent separators are discarded, as are leading or trailing separators.
--
-- > wordsBy (== ':') "::xyz:abc::123::" == ["xyz","abc","123"]
-- > \s -> wordsBy isSpace s == words s
wordsBy :: (a -> Bool) -> [a] -> [[a]]
wordsBy :: forall a. (a -> Bool) -> [a] -> [[a]]
wordsBy a -> Bool
f [a]
s = case forall a. (a -> Bool) -> [a] -> [a]
dropWhile a -> Bool
f [a]
s of
    [] -> []
    a
x:[a]
xs -> (a
xforall a. a -> [a] -> [a]
:[a]
w) forall a. a -> [a] -> [a]
: forall a. (a -> Bool) -> [a] -> [[a]]
wordsBy a -> Bool
f (forall a. [a] -> [a]
drop1 [a]
z)
        where ([a]
w,[a]
z) = forall a. (a -> Bool) -> [a] -> ([a], [a])
break a -> Bool
f [a]
xs

-- | A variant of 'lines' with a custom test. In particular,
--   if there is a trailing separator it will be discarded.
--
-- > linesBy (== ':') "::xyz:abc::123::" == ["","","xyz","abc","","123",""]
-- > \s -> linesBy (== '\n') s == lines s
-- > linesBy (== ';') "my;list;here;" == ["my","list","here"]
linesBy :: (a -> Bool) -> [a] -> [[a]]
linesBy :: forall a. (a -> Bool) -> [a] -> [[a]]
linesBy a -> Bool
f [] = []
linesBy a -> Bool
f [a]
s = forall {a}. (a, [a]) -> [a]
cons forall a b. (a -> b) -> a -> b
$ case forall a. (a -> Bool) -> [a] -> ([a], [a])
break a -> Bool
f [a]
s of
    ([a]
l, [a]
s) -> ([a]
l,) forall a b. (a -> b) -> a -> b
$ case [a]
s of
        [] -> []
        a
_:[a]
s -> forall a. (a -> Bool) -> [a] -> [[a]]
linesBy a -> Bool
f [a]
s
  where
    cons :: (a, [a]) -> [a]
cons ~(a
h, [a]
t) = a
h forall a. a -> [a] -> [a]
: [a]
t -- to fix a space leak, see the GHC defn of lines

-- | Find the first element of a list for which the operation returns 'Just', along
--   with the result of the operation. Like 'find' but useful where the function also
--   computes some expensive information that can be reused. Particular useful
--   when the function is monadic, see 'firstJustM'.
--
-- > firstJust id [Nothing,Just 3]  == Just 3
-- > firstJust id [Nothing,Nothing] == Nothing
firstJust :: (a -> Maybe b) -> [a] -> Maybe b
firstJust :: forall a b. (a -> Maybe b) -> [a] -> Maybe b
firstJust a -> Maybe b
f = forall a. [a] -> Maybe a
listToMaybe forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a b. (a -> Maybe b) -> [a] -> [b]
mapMaybe a -> Maybe b
f


-- | Equivalent to @drop 1@, but likely to be faster and a single lexeme.
--
-- > drop1 ""         == ""
-- > drop1 "test"     == "est"
-- > \xs -> drop 1 xs == drop1 xs
drop1 :: [a] -> [a]
drop1 :: forall a. [a] -> [a]
drop1 [] = []
drop1 (a
x:[a]
xs) = [a]
xs


-- | Equivalent to @dropEnd 1@, but likely to be faster and a single lexeme.
--
-- > dropEnd1 ""         == ""
-- > dropEnd1 "test"     == "tes"
-- > \xs -> dropEnd 1 xs == dropEnd1 xs
dropEnd1 :: [a] -> [a]
dropEnd1 :: forall a. [a] -> [a]
dropEnd1 [] = []
dropEnd1 (a
x:[a]
xs) = forall (t :: * -> *) a b.
Foldable t =>
(a -> b -> b) -> b -> t a -> b
foldr (\a
z a -> [a]
f a
y -> a
y forall a. a -> [a] -> [a]
: a -> [a]
f a
z) (forall a b. a -> b -> a
const []) [a]
xs a
x


-- | Version on `concatMap` generalised to a `Monoid` rather than just a list.
--
-- > mconcatMap Sum [1,2,3] == Sum 6
-- > \f xs -> mconcatMap f xs == concatMap f xs
mconcatMap :: Monoid b => (a -> b) -> [a] -> b
mconcatMap :: forall b a. Monoid b => (a -> b) -> [a] -> b
mconcatMap a -> b
f = forall a. Monoid a => [a] -> a
mconcat forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a b. (a -> b) -> [a] -> [b]
map a -> b
f


-- | Find the first instance of @needle@ in @haystack@.
-- The first element of the returned tuple
-- is the prefix of @haystack@ before @needle@ is matched.  The second
-- is the remainder of @haystack@, starting with the match.
-- If you want the remainder /without/ the match, use 'stripInfix'.
--
-- > breakOn "::" "a::b::c" == ("a", "::b::c")
-- > breakOn "/" "foobar"   == ("foobar", "")
-- > \needle haystack -> let (prefix,match) = breakOn needle haystack in prefix ++ match == haystack
breakOn :: Eq a => [a] -> [a] -> ([a], [a])
breakOn :: forall a. Eq a => [a] -> [a] -> ([a], [a])
breakOn [a]
needle [a]
haystack | [a]
needle forall a. Eq a => [a] -> [a] -> Bool
`isPrefixOf` [a]
haystack = ([], [a]
haystack)
breakOn [a]
needle [] = ([], [])
breakOn [a]
needle (a
x:[a]
xs) = forall a a' b. (a -> a') -> (a, b) -> (a', b)
first (a
xforall a. a -> [a] -> [a]
:) forall a b. (a -> b) -> a -> b
$ forall a. Eq a => [a] -> [a] -> ([a], [a])
breakOn [a]
needle [a]
xs

-- | Similar to 'breakOn', but searches from the end of the
-- string.
--
-- The first element of the returned tuple is the prefix of @haystack@
-- up to and including the last match of @needle@.  The second is the
-- remainder of @haystack@, following the match.
--
-- > breakOnEnd "::" "a::b::c" == ("a::b::", "c")
breakOnEnd :: Eq a => [a] -> [a] -> ([a], [a])
breakOnEnd :: forall a. Eq a => [a] -> [a] -> ([a], [a])
breakOnEnd [a]
needle [a]
haystack = forall a b. (a -> b) -> (a, a) -> (b, b)
both forall a. [a] -> [a]
reverse forall a b. (a -> b) -> a -> b
$ forall a b. (a, b) -> (b, a)
swap forall a b. (a -> b) -> a -> b
$ forall a. Eq a => [a] -> [a] -> ([a], [a])
breakOn (forall a. [a] -> [a]
reverse [a]
needle) (forall a. [a] -> [a]
reverse [a]
haystack)


-- | Break a list into pieces separated by the first
-- list argument, consuming the delimiter. An empty delimiter is
-- invalid, and will cause an error to be raised.
--
-- > splitOn "\r\n" "a\r\nb\r\nd\r\ne" == ["a","b","d","e"]
-- > splitOn "aaa"  "aaaXaaaXaaaXaaa"  == ["","X","X","X",""]
-- > splitOn "x"    "x"                == ["",""]
-- > splitOn "x"    ""                 == [""]
-- > \s x -> s /= "" ==> intercalate s (splitOn s x) == x
-- > \c x -> splitOn [c] x                           == split (==c) x
splitOn :: (Partial, Eq a) => [a] -> [a] -> [[a]]
splitOn :: forall a. (Partial, Eq a) => [a] -> [a] -> [[a]]
splitOn [] [a]
_ = forall a. Partial => String -> a
error String
"splitOn, needle may not be empty"
splitOn [a]
_ [] = [[]]
splitOn [a]
needle [a]
haystack = [a]
a forall a. a -> [a] -> [a]
: if forall (t :: * -> *) a. Foldable t => t a -> Bool
null [a]
b then [] else forall a. (Partial, Eq a) => [a] -> [a] -> [[a]]
splitOn [a]
needle forall a b. (a -> b) -> a -> b
$ forall a. Int -> [a] -> [a]
drop (forall (t :: * -> *) a. Foldable t => t a -> Int
length [a]
needle) [a]
b
    where ([a]
a,[a]
b) = forall a. Eq a => [a] -> [a] -> ([a], [a])
breakOn [a]
needle [a]
haystack


-- | Splits a list into components delimited by separators,
-- where the predicate returns True for a separator element.  The
-- resulting components do not contain the separators.  Two adjacent
-- separators result in an empty component in the output.
--
-- > split (== 'a') "aabbaca" == ["","","bb","c",""]
-- > split (== 'a') ""        == [""]
-- > split (== ':') "::xyz:abc::123::" == ["","","xyz","abc","","123","",""]
-- > split (== ',') "my,list,here" == ["my","list","here"]
split :: (a -> Bool) -> [a] -> [[a]]
split :: forall a. (a -> Bool) -> [a] -> [[a]]
split a -> Bool
f [] = [[]]
split a -> Bool
f (a
x:[a]
xs) | a -> Bool
f a
x = [] forall a. a -> [a] -> [a]
: forall a. (a -> Bool) -> [a] -> [[a]]
split a -> Bool
f [a]
xs
split a -> Bool
f (a
x:[a]
xs) | [a]
y:[[a]]
ys <- forall a. (a -> Bool) -> [a] -> [[a]]
split a -> Bool
f [a]
xs = (a
xforall a. a -> [a] -> [a]
:[a]
y) forall a. a -> [a] -> [a]
: [[a]]
ys


-- | A version of 'dropWhileEnd' but with different strictness properties.
--   The function 'dropWhileEnd' can be used on an infinite list and tests the property
--   on each character. In contrast, 'dropWhileEnd'' is strict in the spine of the list
--   but only tests the trailing suffix.
--   This version usually outperforms 'dropWhileEnd' if the list is short or the test is expensive.
--   Note the tests below cover both the prime and non-prime variants.
--
-- > dropWhileEnd  isSpace "ab cde  " == "ab cde"
-- > dropWhileEnd' isSpace "ab cde  " == "ab cde"
-- > last (dropWhileEnd  even [undefined,3]) == undefined
-- > last (dropWhileEnd' even [undefined,3]) == 3
-- > head (dropWhileEnd  even (3:undefined)) == 3
-- > head (dropWhileEnd' even (3:undefined)) == undefined
dropWhileEnd' :: (a -> Bool) -> [a] -> [a]
dropWhileEnd' :: forall a. (a -> Bool) -> [a] -> [a]
dropWhileEnd' a -> Bool
p = forall (t :: * -> *) a b.
Foldable t =>
(a -> b -> b) -> b -> t a -> b
foldr (\a
x [a]
xs -> if forall (t :: * -> *) a. Foldable t => t a -> Bool
null [a]
xs Bool -> Bool -> Bool
&& a -> Bool
p a
x then [] else a
x forall a. a -> [a] -> [a]
: [a]
xs) []


-- | Drops the given prefix from a list.
--   It returns the original sequence if the sequence doesn't start with the given prefix.
--
-- > dropPrefix "Mr. " "Mr. Men" == "Men"
-- > dropPrefix "Mr. " "Dr. Men" == "Dr. Men"
dropPrefix :: Eq a => [a] -> [a] -> [a]
dropPrefix :: forall a. Eq a => [a] -> [a] -> [a]
dropPrefix [a]
a [a]
b = forall a. a -> Maybe a -> a
fromMaybe [a]
b forall a b. (a -> b) -> a -> b
$ forall a. Eq a => [a] -> [a] -> Maybe [a]
stripPrefix [a]
a [a]
b


-- | Drops the given suffix from a list.
--   It returns the original sequence if the sequence doesn't end with the given suffix.
--
-- > dropSuffix "!" "Hello World!"  == "Hello World"
-- > dropSuffix "!" "Hello World!!" == "Hello World!"
-- > dropSuffix "!" "Hello World."  == "Hello World."
dropSuffix :: Eq a => [a] -> [a] -> [a]
dropSuffix :: forall a. Eq a => [a] -> [a] -> [a]
dropSuffix [a]
a [a]
b = forall a. a -> Maybe a -> a
fromMaybe [a]
b forall a b. (a -> b) -> a -> b
$ forall a. Eq a => [a] -> [a] -> Maybe [a]
stripSuffix [a]
a [a]
b

-- | Return the prefix of the second list if its suffix
--   matches the entire first list.
--
-- Examples:
--
-- > stripSuffix "bar" "foobar" == Just "foo"
-- > stripSuffix ""    "baz"    == Just "baz"
-- > stripSuffix "foo" "quux"   == Nothing
stripSuffix :: Eq a => [a] -> [a] -> Maybe [a]
stripSuffix :: forall a. Eq a => [a] -> [a] -> Maybe [a]
stripSuffix [a]
a [a]
b = forall a. [a] -> [a]
reverse forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> forall a. Eq a => [a] -> [a] -> Maybe [a]
stripPrefix (forall a. [a] -> [a]
reverse [a]
a) (forall a. [a] -> [a]
reverse [a]
b)


-- | Return the the string before and after the search string,
--   or 'Nothing' if the search string is not present.
--
-- Examples:
--
-- > stripInfix "::" "a::b::c" == Just ("a", "b::c")
-- > stripInfix "/" "foobar"   == Nothing
stripInfix :: Eq a => [a] -> [a] -> Maybe ([a], [a])
stripInfix :: forall a. Eq a => [a] -> [a] -> Maybe ([a], [a])
stripInfix [a]
needle [a]
haystack | Just [a]
rest <- forall a. Eq a => [a] -> [a] -> Maybe [a]
stripPrefix [a]
needle [a]
haystack = forall a. a -> Maybe a
Just ([], [a]
rest)
stripInfix [a]
needle [] = forall a. Maybe a
Nothing
stripInfix [a]
needle (a
x:[a]
xs) = forall a a' b. (a -> a') -> (a, b) -> (a', b)
first (a
xforall a. a -> [a] -> [a]
:) forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> forall a. Eq a => [a] -> [a] -> Maybe ([a], [a])
stripInfix [a]
needle [a]
xs


-- | Similar to 'stripInfix', but searches from the end of the
-- string.
--
-- > stripInfixEnd "::" "a::b::c" == Just ("a::b", "c")
stripInfixEnd :: Eq a => [a] -> [a] -> Maybe ([a], [a])
stripInfixEnd :: forall a. Eq a => [a] -> [a] -> Maybe ([a], [a])
stripInfixEnd [a]
needle [a]
haystack = forall a b. (a -> b) -> (a, a) -> (b, b)
both forall a. [a] -> [a]
reverse forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a b. (a, b) -> (b, a)
swap forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> forall a. Eq a => [a] -> [a] -> Maybe ([a], [a])
stripInfix (forall a. [a] -> [a]
reverse [a]
needle) (forall a. [a] -> [a]
reverse [a]
haystack)


-- | Split a list into chunks of a given size. The last chunk may contain
--   fewer than n elements. The chunk size must be positive.
--
-- > chunksOf 3 "my test" == ["my ","tes","t"]
-- > chunksOf 3 "mytest"  == ["myt","est"]
-- > chunksOf 8 ""        == []
-- > chunksOf 0 "test"    == undefined
chunksOf :: Partial => Int -> [a] -> [[a]]
chunksOf :: forall a. Partial => Int -> [a] -> [[a]]
chunksOf Int
i [a]
xs | Int
i forall a. Ord a => a -> a -> Bool
<= Int
0 = forall a. Partial => String -> a
error forall a b. (a -> b) -> a -> b
$ String
"chunksOf, number must be positive, got " forall a. [a] -> [a] -> [a]
++ forall a. Show a => a -> String
show Int
i
chunksOf Int
i [a]
xs = forall a b. ([a] -> (b, [a])) -> [a] -> [b]
repeatedly (forall a. Int -> [a] -> ([a], [a])
splitAt Int
i) [a]
xs


-- | /O(n log n)/. The 'nubSort' function sorts and removes duplicate elements from a list.
-- In particular, it keeps only the first occurrence of each element.
--
-- > nubSort "this is a test" == " aehist"
-- > \xs -> nubSort xs == nub (sort xs)
nubSort :: Ord a => [a] -> [a]
nubSort :: forall a. Ord a => [a] -> [a]
nubSort = forall a. (a -> a -> Ordering) -> [a] -> [a]
nubSortBy forall a. Ord a => a -> a -> Ordering
compare

-- | A version of 'nubSort' which operates on a portion of the value.
--
-- > nubSortOn length ["a","test","of","this"] == ["a","of","test"]
nubSortOn :: Ord b => (a -> b) -> [a] -> [a]
nubSortOn :: forall b a. Ord b => (a -> b) -> [a] -> [a]
nubSortOn a -> b
f = forall a. (a -> a -> Ordering) -> [a] -> [a]
nubSortBy (forall a. Ord a => a -> a -> Ordering
compare forall {t} {t} {p}. (t -> t -> t) -> (p -> t) -> p -> p -> t
`on` a -> b
f)

-- | A version of 'nubSort' with a custom predicate.
--
-- > nubSortBy (compare `on` length) ["a","test","of","this"] == ["a","of","test"]
nubSortBy :: (a -> a -> Ordering) -> [a] -> [a]
nubSortBy :: forall a. (a -> a -> Ordering) -> [a] -> [a]
nubSortBy a -> a -> Ordering
cmp = [a] -> [a]
f forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a. (a -> a -> Ordering) -> [a] -> [a]
sortBy a -> a -> Ordering
cmp
    where f :: [a] -> [a]
f (a
x1:a
x2:[a]
xs) | a -> a -> Ordering
cmp a
x1 a
x2 forall a. Eq a => a -> a -> Bool
== Ordering
EQ = [a] -> [a]
f (a
x1forall a. a -> [a] -> [a]
:[a]
xs)
          f (a
x:[a]
xs) = a
x forall a. a -> [a] -> [a]
: [a] -> [a]
f [a]
xs
          f [] = []

-- | /O(n log n)/. The 'nubOrd' function removes duplicate elements from a list.
-- In particular, it keeps only the first occurrence of each element.
-- Unlike the standard 'nub' operator, this version requires an 'Ord' instance
-- and consequently runs asymptotically faster.
--
-- > nubOrd "this is a test" == "this ae"
-- > nubOrd (take 4 ("this" ++ undefined)) == "this"
-- > \xs -> nubOrd xs == nub xs
nubOrd :: Ord a => [a] -> [a]
nubOrd :: forall a. Ord a => [a] -> [a]
nubOrd = forall a. (a -> a -> Ordering) -> [a] -> [a]
nubOrdBy forall a. Ord a => a -> a -> Ordering
compare

-- | A version of 'nubOrd' which operates on a portion of the value.
--
-- > nubOrdOn length ["a","test","of","this"] == ["a","test","of"]
nubOrdOn :: Ord b => (a -> b) -> [a] -> [a]
nubOrdOn :: forall b a. Ord b => (a -> b) -> [a] -> [a]
nubOrdOn a -> b
f = forall a b. (a -> b) -> [a] -> [b]
map forall a b. (a, b) -> b
snd forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a. (a -> a -> Ordering) -> [a] -> [a]
nubOrdBy (forall a. Ord a => a -> a -> Ordering
compare forall {t} {t} {p}. (t -> t -> t) -> (p -> t) -> p -> p -> t
`on` forall a b. (a, b) -> a
fst) forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a b. (a -> b) -> [a] -> [b]
map (a -> b
f forall a b c. (a -> b) -> (a -> c) -> a -> (b, c)
&&& forall a. a -> a
id)

-- | A version of 'nubOrd' with a custom predicate.
--
-- > nubOrdBy (compare `on` length) ["a","test","of","this"] == ["a","test","of"]
nubOrdBy :: (a -> a -> Ordering) -> [a] -> [a]
nubOrdBy :: forall a. (a -> a -> Ordering) -> [a] -> [a]
nubOrdBy a -> a -> Ordering
cmp [a]
xs = RB a -> [a] -> [a]
f forall a. RB a
E [a]
xs
    where f :: RB a -> [a] -> [a]
f RB a
seen [] = []
          f RB a
seen (a
x:[a]
xs) | forall a. (a -> a -> Ordering) -> a -> RB a -> Bool
memberRB a -> a -> Ordering
cmp a
x RB a
seen = RB a -> [a] -> [a]
f RB a
seen [a]
xs
                        | Bool
otherwise = a
x forall a. a -> [a] -> [a]
: RB a -> [a] -> [a]
f (forall a. (a -> a -> Ordering) -> a -> RB a -> RB a
insertRB a -> a -> Ordering
cmp a
x RB a
seen) [a]
xs

---------------------------------------------------------------------
-- OKASAKI RED BLACK TREE
-- Taken from https://www.cs.kent.ac.uk/people/staff/smk/redblack/Untyped.hs
-- But with the Color = R|B fused into the tree

data RB a = E | T_R (RB a) a (RB a) | T_B (RB a) a (RB a) deriving Int -> RB a -> String -> String
forall a. Show a => Int -> RB a -> String -> String
forall a. Show a => [RB a] -> String -> String
forall a. Show a => RB a -> String
forall a.
(Int -> a -> String -> String)
-> (a -> String) -> ([a] -> String -> String) -> Show a
showList :: [RB a] -> String -> String
$cshowList :: forall a. Show a => [RB a] -> String -> String
show :: RB a -> String
$cshow :: forall a. Show a => RB a -> String
showsPrec :: Int -> RB a -> String -> String
$cshowsPrec :: forall a. Show a => Int -> RB a -> String -> String
Show

{- Insertion and membership test as by Okasaki -}
insertRB :: (a -> a -> Ordering) -> a -> RB a -> RB a
insertRB :: forall a. (a -> a -> Ordering) -> a -> RB a -> RB a
insertRB a -> a -> Ordering
cmp a
x RB a
s = case RB a -> RB a
ins RB a
s of
    T_R RB a
a a
z RB a
b -> forall a. RB a -> a -> RB a -> RB a
T_B RB a
a a
z RB a
b
    RB a
x -> RB a
x
    where
    ins :: RB a -> RB a
ins RB a
E = forall a. RB a -> a -> RB a -> RB a
T_R forall a. RB a
E a
x forall a. RB a
E
    ins s :: RB a
s@(T_B RB a
a a
y RB a
b) = case a -> a -> Ordering
cmp a
x a
y of
        Ordering
LT -> forall a. RB a -> a -> RB a -> RB a
lbalance (RB a -> RB a
ins RB a
a) a
y RB a
b
        Ordering
GT -> forall a. RB a -> a -> RB a -> RB a
rbalance RB a
a a
y (RB a -> RB a
ins RB a
b)
        Ordering
EQ -> RB a
s
    ins s :: RB a
s@(T_R RB a
a a
y RB a
b) = case a -> a -> Ordering
cmp a
x a
y of
        Ordering
LT -> forall a. RB a -> a -> RB a -> RB a
T_R (RB a -> RB a
ins RB a
a) a
y RB a
b
        Ordering
GT -> forall a. RB a -> a -> RB a -> RB a
T_R RB a
a a
y (RB a -> RB a
ins RB a
b)
        Ordering
EQ -> RB a
s

memberRB :: (a -> a -> Ordering) -> a -> RB a -> Bool
memberRB :: forall a. (a -> a -> Ordering) -> a -> RB a -> Bool
memberRB a -> a -> Ordering
cmp a
x RB a
E = Bool
False
memberRB a -> a -> Ordering
cmp a
x (T_R RB a
a a
y RB a
b) = case a -> a -> Ordering
cmp a
x a
y of
    Ordering
LT -> forall a. (a -> a -> Ordering) -> a -> RB a -> Bool
memberRB a -> a -> Ordering
cmp a
x RB a
a
    Ordering
GT -> forall a. (a -> a -> Ordering) -> a -> RB a -> Bool
memberRB a -> a -> Ordering
cmp a
x RB a
b
    Ordering
EQ -> Bool
True
memberRB a -> a -> Ordering
cmp a
x (T_B RB a
a a
y RB a
b) = case a -> a -> Ordering
cmp a
x a
y of
    Ordering
LT -> forall a. (a -> a -> Ordering) -> a -> RB a -> Bool
memberRB a -> a -> Ordering
cmp a
x RB a
a
    Ordering
GT -> forall a. (a -> a -> Ordering) -> a -> RB a -> Bool
memberRB a -> a -> Ordering
cmp a
x RB a
b
    Ordering
EQ -> Bool
True

{- balance: first equation is new,
   to make it work with a weaker invariant -}
lbalance, rbalance :: RB a -> a -> RB a -> RB a
lbalance :: forall a. RB a -> a -> RB a -> RB a
lbalance (T_R RB a
a a
x RB a
b) a
y (T_R RB a
c a
z RB a
d) = forall a. RB a -> a -> RB a -> RB a
T_R (forall a. RB a -> a -> RB a -> RB a
T_B RB a
a a
x RB a
b) a
y (forall a. RB a -> a -> RB a -> RB a
T_B RB a
c a
z RB a
d)
lbalance (T_R (T_R RB a
a a
x RB a
b) a
y RB a
c) a
z RB a
d = forall a. RB a -> a -> RB a -> RB a
T_R (forall a. RB a -> a -> RB a -> RB a
T_B RB a
a a
x RB a
b) a
y (forall a. RB a -> a -> RB a -> RB a
T_B RB a
c a
z RB a
d)
lbalance (T_R RB a
a a
x (T_R RB a
b a
y RB a
c)) a
z RB a
d = forall a. RB a -> a -> RB a -> RB a
T_R (forall a. RB a -> a -> RB a -> RB a
T_B RB a
a a
x RB a
b) a
y (forall a. RB a -> a -> RB a -> RB a
T_B RB a
c a
z RB a
d)
lbalance RB a
a a
x RB a
b = forall a. RB a -> a -> RB a -> RB a
T_B RB a
a a
x RB a
b
rbalance :: forall a. RB a -> a -> RB a -> RB a
rbalance (T_R RB a
a a
x RB a
b) a
y (T_R RB a
c a
z RB a
d) = forall a. RB a -> a -> RB a -> RB a
T_R (forall a. RB a -> a -> RB a -> RB a
T_B RB a
a a
x RB a
b) a
y (forall a. RB a -> a -> RB a -> RB a
T_B RB a
c a
z RB a
d)
rbalance RB a
a a
x (T_R RB a
b a
y (T_R RB a
c a
z RB a
d)) = forall a. RB a -> a -> RB a -> RB a
T_R (forall a. RB a -> a -> RB a -> RB a
T_B RB a
a a
x RB a
b) a
y (forall a. RB a -> a -> RB a -> RB a
T_B RB a
c a
z RB a
d)
rbalance RB a
a a
x (T_R (T_R RB a
b a
y RB a
c) a
z RB a
d) = forall a. RB a -> a -> RB a -> RB a
T_R (forall a. RB a -> a -> RB a -> RB a
T_B RB a
a a
x RB a
b) a
y (forall a. RB a -> a -> RB a -> RB a
T_B RB a
c a
z RB a
d)
rbalance RB a
a a
x RB a
b = forall a. RB a -> a -> RB a -> RB a
T_B RB a
a a
x RB a
b


-- | Like 'zipWith', but keep going to the longest value. The function
--   argument will always be given at least one 'Just', and while both
--   lists have items, two 'Just' values.
--
-- > zipWithLongest (,) "a" "xyz" == [(Just 'a', Just 'x'), (Nothing, Just 'y'), (Nothing, Just 'z')]
-- > zipWithLongest (,) "a" "x" == [(Just 'a', Just 'x')]
-- > zipWithLongest (,) "" "x" == [(Nothing, Just 'x')]
zipWithLongest :: (Maybe a -> Maybe b -> c) -> [a] -> [b] -> [c]
zipWithLongest :: forall a b c. (Maybe a -> Maybe b -> c) -> [a] -> [b] -> [c]
zipWithLongest Maybe a -> Maybe b -> c
f [] [] = []
zipWithLongest Maybe a -> Maybe b -> c
f (a
x:[a]
xs) (b
y:[b]
ys) = Maybe a -> Maybe b -> c
f (forall a. a -> Maybe a
Just a
x) (forall a. a -> Maybe a
Just b
y) forall a. a -> [a] -> [a]
: forall a b c. (Maybe a -> Maybe b -> c) -> [a] -> [b] -> [c]
zipWithLongest Maybe a -> Maybe b -> c
f [a]
xs [b]
ys
zipWithLongest Maybe a -> Maybe b -> c
f [] [b]
ys = forall a b. (a -> b) -> [a] -> [b]
map (Maybe a -> Maybe b -> c
f forall a. Maybe a
Nothing forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a. a -> Maybe a
Just) [b]
ys
zipWithLongest Maybe a -> Maybe b -> c
f [a]
xs [] = forall a b. (a -> b) -> [a] -> [b]
map ((Maybe a -> Maybe b -> c
`f` forall a. Maybe a
Nothing) forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a. a -> Maybe a
Just) [a]
xs

-- | Lazily compare the length of a 'Foldable' with a number.
--
-- > compareLength [1,2,3] 1 == GT
-- > compareLength [1,2] 2 == EQ
-- > \(xs :: [Int]) n -> compareLength xs n == compare (length xs) n
-- > compareLength (1:2:3:undefined) 2 == GT
compareLength :: (Ord b, Num b, Foldable f) => f a -> b -> Ordering
compareLength :: forall b (f :: * -> *) a.
(Ord b, Num b, Foldable f) =>
f a -> b -> Ordering
compareLength = forall (t :: * -> *) a b.
Foldable t =>
(a -> b -> b) -> b -> t a -> b
foldr (\a
_ b -> Ordering
acc b
n -> if b
n forall a. Ord a => a -> a -> Bool
> b
0 then b -> Ordering
acc (b
n forall a. Num a => a -> a -> a
- b
1) else Ordering
GT) (forall a. Ord a => a -> a -> Ordering
compare b
0)

-- | Lazily compare the length of two 'Foldable's.
-- > comparingLength [1,2,3] [False] == GT
-- > comparingLength [1,2] "ab" == EQ
-- > \(xs :: [Int]) (ys :: [Int]) -> comparingLength xs ys == Data.Ord.comparing length xs ys
-- > comparingLength [1,2] (1:2:3:undefined) == LT
-- > comparingLength (1:2:3:undefined) [1,2] == GT
comparingLength :: (Foldable f1, Foldable f2) => f1 a -> f2 b -> Ordering
comparingLength :: forall (f1 :: * -> *) (f2 :: * -> *) a b.
(Foldable f1, Foldable f2) =>
f1 a -> f2 b -> Ordering
comparingLength f1 a
x f2 b
y = forall {a} {a}. [a] -> [a] -> Ordering
go (forall (t :: * -> *) a. Foldable t => t a -> [a]
toList f1 a
x) (forall (t :: * -> *) a. Foldable t => t a -> [a]
toList f2 b
y)
  where
    go :: [a] -> [a] -> Ordering
go [] [] = Ordering
EQ
    go [] (a
_:[a]
_) = Ordering
LT
    go (a
_:[a]
_) [] = Ordering
GT
    go (a
_:[a]
xs) (a
_:[a]
ys) = [a] -> [a] -> Ordering
go [a]
xs [a]
ys