162 lines
4.7 KiB
Elm
162 lines
4.7 KiB
Elm
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module List where
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import Native.Utils (min, max)
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import Native.List as L
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-- Add an element to the front of a list `(1 :: [2,3] == [1,2,3])`
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(::) : a -> [a] -> [a]
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-- Puts two appendable things together:
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--
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-- [1,1] ++ [2,3] == [1,1,2,3]
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-- "abc" ++ "123" == "abc123"
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(++) : Appendable a -> Appendable a -> Appendable a
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-- Extract the first element of a list. List must be non-empty.
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-- `(head [1,2,3] == 1)`
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head : [a] -> a
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-- Extract the elements after the head of the list. List must be non-empty.
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-- `(tail [1,2,3] == [2,3])`
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tail : [a] -> [a]
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-- Extract the last element of a list. List must be non-empty.
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-- `(last [1,2,3] == 3)`
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last : [a] -> a
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-- Check if a list is empty `(isEmpty [] == True)`
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isEmpty : [a] -> Bool
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isEmpty xs =
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case xs of
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[] -> True
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_ -> False
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-- Apply a function to every element of a list: `(map sqrt [1,4,9] == [1,2,3])`
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map : (a -> b) -> [a] -> [b]
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-- Reduce a list from the left: `(foldl (::) [] "gateman" == "nametag")`
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foldl : (a -> b -> b) -> b -> [a] -> b
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-- Reduce a list from the right: `(foldr (+) 0 [1,2,3] == 6)`
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foldr : (a -> b -> b) -> b -> [a] -> b
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-- Reduce a list from the left without a base case. List must be non-empty.
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foldl1 : (a -> a -> a) -> [a] -> a
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-- Reduce a list from the right without a base case. List must be non-empty.
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foldr1 : (a -> a -> a) -> [a] -> a
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-- Reduce a list from the left, building up all of the intermediate results into a list.
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--
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-- scanl (+) 0 [1,2,3,4] == [0,1,3,6,10]
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scanl : (a -> b -> b) -> b -> [a] -> [b]
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-- Same as scanl but it doesn't require a base case. List must be non-empty.
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--
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-- scanl1 (+) [1,2,3,4] == [1,3,6,10]
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scanl1 : (a -> a -> a) -> [a] -> [a]
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-- Filter out elements which do not satisfy the predicate: `(filter isLower "AaBbCc" == "abc")`
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filter : (a -> Bool) -> [a] -> [a]
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-- Determine the length of a list: `(length "innumerable" == 11)`
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length : [a] -> Int
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-- Reverse a list. `(reverse [1..4] == [4,3,2,1])`
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reverse : [a] -> [a]
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-- Check to see if all elements satisfy the predicate.
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all : (a -> Bool) -> [a] -> Bool
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-- Check to see if any elements satisfy the predicate.
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any : (a -> Bool) -> [a] -> Bool
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-- Check to see if all elements are True.
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and : [Bool] -> Bool
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-- Check to see if any elements are True.
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or : [Bool] -> Bool
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-- Concatenate a list of appendable things:
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--
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-- concat ["tree","house"] == "treehouse"
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concat : [Appendable a] -> Appendable a
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-- Map a given function onto a list and flatten the resulting lists.
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--
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-- concatMap f xs == concat (map f xs)
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concatMap : (a -> Appendable b) -> [a] -> Appendable b
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concatMap f = L.concat . L.map f
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-- Get the sum of the list elements. `(sum [1..4] == 10)`
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sum : [Number a] -> Number a
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sum = L.foldl (+) 0
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-- Get the product of the list elements. `(product [1..4] == 24)`
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product : [Number a] -> Number a
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product = L.foldl (*) 1
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-- Find the highest number in a non-empty list.
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maximum : [Number a] -> Number a
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maximum = L.foldl1 max
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-- Find the lowest number in a non-empty list.
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minimum : [Number a] -> Number a
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minimum = L.foldl1 min
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-- Split a list based on the predicate.
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partition : (a -> Bool) -> [a] -> ([a],[a])
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partition pred lst =
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case lst of
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[] -> ([],[])
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x::xs -> let (bs,cs) = partition pred xs in
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if pred x then (x::bs,cs) else (bs,x::cs)
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-- Combine two lists, combining them into tuples pairwise.
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-- If one list is longer, the extra elements are dropped.
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--
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-- zip [1,2,3] [6,7] == [(1,6),(2,7)]
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-- zip == zipWith (,)
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zip : [a] -> [b] -> [(a,b)]
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-- Combine two lists, combining them with the given function.
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-- If one list is longer, the extra elements are dropped.
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--
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-- zipWith (+) [1,2,3] [1,2,3,4] == [2,4,6]
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zipWith : (a -> b -> c) -> [a] -> [b] -> [c]
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-- Decompose a list of tuples.
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unzip : [(a,b)] -> ([a],[b])
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unzip pairs =
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case pairs of
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[] -> ([],[])
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(x,y)::ps -> let (xs,ys) = (unzip ps) in (x::xs,y::ys)
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-- Split a list with a given seperator.
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--
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-- split "," "hello,there,friend" == ["hello", "there", "friend"]
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split : [a] -> [a] -> [[a]]
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-- Places the given value between all of the lists in the second argument
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-- and concatenates the result.
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--
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-- join "a" ["H","w","ii","n"] == "Hawaiian"
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join : Appendable a -> [Appendable a] -> Appendable a
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-- Places the given value between all members of the given list.
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--
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-- intersperse ' ' "INCEPTION" == "I N C E P T I O N"
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intersperse : a -> [a] -> [a]
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intersperse sep xs =
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case xs of
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a::b::cs -> a :: sep :: intersperse sep (b::cs)
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[a] -> [a]
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[] -> []
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-- Take the first n members of a list: `(take 2 [1,2,3,4] == [1,2])`
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take : Int -> [a] -> [a]
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-- Drop the first n members of a list: `(drop 2 [1,2,3,4] == [3,4])`
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drop : Int -> [a] -> [a]
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