module List where

import Native.Utils (min, max)
import Native.List as L

-- Add an element to the front of a list `(1 :: [2,3] == [1,2,3])`
(::) : a -> [a] -> [a]

-- Puts two appendable things together:
--
--         [1,1] ++ [2,3] == [1,1,2,3]
--         "abc" ++ "123" == "abc123"
(++) : Appendable a -> Appendable a -> Appendable a

-- Extract the first element of a list. List must be non-empty.
-- `(head [1,2,3] == 1)`
head : [a] -> a

-- Extract the elements after the head of the list. List must be non-empty.
--  `(tail [1,2,3] == [2,3])`
tail : [a] -> [a]

-- Extract the last element of a list. List must be non-empty.
-- `(last [1,2,3] == 3)`
last : [a] -> a

-- Apply a function to every element of a list: `(map sqrt [1,4,9] == [1,2,3])`
map  : (a -> b) -> [a] -> [b]

-- Reduce a list from the left: `(foldl (::) [] "gateman" == "nametag")`
foldl  : (a -> b -> b) -> b -> [a] -> b

-- Reduce a list from the right: `(foldr (+) 0 [1,2,3] == 6)`
foldr  : (a -> b -> b) -> b -> [a] -> b

-- Reduce a list from the left without a base case. List must be non-empty.
foldl1 : (a -> a -> a) -> [a] -> a

-- Reduce a list from the right without a base case. List must be non-empty.
foldr1 : (a -> a -> a) -> [a] -> a

-- Reduce a list from the left, building up all of the intermediate results into a list.
--
--         scanl (+) 0 [1,2,3,4] == [0,1,3,6,10]
scanl  : (a -> b -> b) -> b -> [a] -> [b]

-- Same as scanl but it doesn't require a base case. List must be non-empty.
--
--         scanl1 (+) [1,2,3,4] == [1,3,6,10]
scanl1 : (a -> a -> a) -> [a] -> [a]

-- Filter out elements which do not satisfy the predicate: `(filter isLower "AaBbCc" == "abc")`
filter  : (a -> Bool) -> [a] -> [a]

-- Determine the length of a list: `(length "innumerable" == 11)`
length  : [a] -> Int

-- Reverse a list. `(reverse [1..4] == [4,3,2,1])`
reverse : [a] -> [a]

-- Check to see if all elements satisfy the predicate.
all : (a -> Bool) -> [a] -> Bool

-- Check to see if any elements satisfy the predicate.
any : (a -> Bool) -> [a] -> Bool

-- Check to see if all elements are True.
and : [Bool] -> Bool

-- Check to see if any elements are True.
or  : [Bool] -> Bool

-- Concatenate a list of appendable things:
--
--         concat ["tree","house"] == "treehouse"
concat : [Appendable a] -> Appendable a

-- Map a given function onto a list and flatten the resulting lists.
--
--         concatMap f xs == concat (map f xs)
concatMap : (a -> Appendable b) -> [a] -> Appendable b
concatMap f = L.concat . L.map f

-- Get the sum of the list elements. `(sum [1..4] == 10)`
sum : [Number a] -> Number a
sum = L.foldl (+) 0

-- Get the product of the list elements. `(product [1..4] == 24)`
product : [Number a] -> Number a
product = L.foldl (*) 1

-- Find the highest number in a non-empty list.
maximum : [Number a] -> Number a
maximum = L.foldl1 max

-- Find the lowest number in a non-empty list.
minimum : [Number a] -> Number a
minimum = L.foldl1 min

-- Split a list based on the predicate.
partition : (a -> Bool) -> [a] -> ([a],[a])
partition pred lst =
    case lst of
      []    -> ([],[])
      x::xs -> let (bs,cs) = partition pred xs in
               if pred x then (x::bs,cs) else (bs,x::cs)

-- Combine two lists, combining them into tuples pairwise.
-- If one list is longer, the extra elements are dropped.
--
--         zip [1,2,3] [6,7] == [(1,6),(2,7)]
--         zip == zipWith (,)
zip : [a] -> [b] -> [(a,b)]

-- Combine two lists, combining them with the given function.
-- If one list is longer, the extra elements are dropped.
--
--         zipWith (+) [1,2,3] [1,2,3,4] == [2,4,6]
zipWith : (a -> b -> c) -> [a] -> [b] -> [c]

-- Decompose a list of tuples.
unzip : [(a,b)] -> ([a],[b])
unzip pairs =
  case pairs of
    []        -> ([],[])
    (x,y)::ps -> let (xs,ys) = (unzip ps) in (x::xs,y::ys)

-- Split a list with a given seperator.
--
--         split "," "hello,there,friend" == ["hello", "there", "friend"]
split : [a] -> [a] -> [[a]]

-- Places the given value between all of the lists in the second argument
-- and concatenates the result. 
--
--         join "a" ["H","w","ii","n"] == "Hawaiian"
join  : Appendable a -> [Appendable a] -> Appendable a

-- Places the given value between all members of the given list.
--
--         intersperse ' ' "INCEPTION" == "I N C E P T I O N"
intersperse : a -> [a] -> [a]
intersperse sep xs =
  case xs of 
    a::b::cs -> a :: sep :: intersperse sep (b::cs)
    [a] -> [a]
    []  -> []

-- Take the first n members of a list: `(take 2 [1,2,3,4] == [1,2])`
take : Int -> [a] -> [a]

-- Drop the first n members of a list: `(drop 2 [1,2,3,4] == [3,4])`
drop : Int -> [a] -> [a]