# View Source List(Elixir v1.15.7)

Linked lists hold zero, one, or more elements in the chosen order.

Lists in Elixir are specified between square brackets:

iex> [1, "two", 3, :four]
[1, "two", 3, :four]

Two lists can be concatenated and subtracted using the ++/2 and --/2 operators:

iex> [1, 2, 3] ++ [4, 5, 6]
[1, 2, 3, 4, 5, 6]
iex> [1, true, 2, false, 3, true] -- [true, false]
[1, 2, 3, true]

An element can be prepended to a list using |:

iex> new = 0
iex> list = [1, 2, 3]
iex> [new | list]
[0, 1, 2, 3]

Lists in Elixir are effectively linked lists, which means they are internally represented in pairs containing the head and the tail of a list:

iex> [head | tail] = [1, 2, 3]
1
iex> tail
[2, 3]

Similarly, we could write the list [1, 2, 3] using only such pairs (called cons cells):

iex> [1 | [2 | [3 | []]]]
[1, 2, 3]

Some lists, called improper lists, do not have an empty list as the second element in the last cons cell:

iex> [1 | [2 | [3 | 4]]]
[1, 2, 3 | 4]

Although improper lists are generally avoided, they are used in some special circumstances like iodata and chardata entities (see the IO module).

Due to their cons cell based representation, prepending an element to a list is always fast (constant time), while appending becomes slower as the list grows in size (linear time):

iex> list = [1, 2, 3]
iex> [0 | list] # fast
[0, 1, 2, 3]
iex> list ++ [4] # slow
[1, 2, 3, 4]

Most of the functions in this module work in linear time. This means that, that the time it takes to perform an operation grows at the same rate as the length of the list. For example length/1 and last/1 will run in linear time because they need to iterate through every element of the list, but first/1 will run in constant time because it only needs the first element.

Lists also implement the Enumerable protocol, so many functions to work with lists are found in the Enum module. Additionally, the following functions and operators for lists are found in Kernel:

## Charlists

If a list is made of non-negative integers, where each integer represents a Unicode code point, the list can also be called a charlist. These integers must:

• be within the range 0..0x10FFFF (0..1_114_111);
• and be out of the range 0xD800..0xDFFF (55_296..57_343), which is reserved in Unicode for UTF-16 surrogate pairs.

Elixir uses the ~c sigil to define charlists:

iex> ~c"héllo"
[104, 233, 108, 108, 111]

In particular, charlists will be printed back by default with the ~c sigil if they contain only printable ASCII characters:

iex> ~c"abc"
~c"abc"

Even though the representation changed, the raw data does remain a list of integers, which can be handled as such:

iex> inspect(~c"abc", charlists: :as_list)
"[97, 98, 99]"
iex> Enum.map(~c"abc", fn num -> 1000 + num end)
[1097, 1098, 1099]

You can use the IEx.Helpers.i/1 helper to get a condensed rundown on charlists in IEx when you encounter them, which shows you the type, description and also the raw representation in one single summary.

The rationale behind this behaviour is to better support Erlang libraries which may return text as charlists instead of Elixir strings. In Erlang, charlists are the default way of handling strings, while in Elixir it's binaries. One example of such functions is Application.loaded_applications/0:

#=>  [
#=>    {:stdlib, ~c"ERTS  CXC 138 10", ~c"2.6"},
#=>    {:compiler, ~c"ERTS  CXC 138 10", ~c"6.0.1"},
#=>    {:elixir, ~c"elixir", ~c"1.0.0"},
#=>    {:kernel, ~c"ERTS  CXC 138 10", ~c"4.1"},
#=>    {:logger, ~c"logger", ~c"1.0.0"}
#=>  ]

A list can be checked if it is made of only printable ASCII characters with ascii_printable?/2.

Improper lists are never deemed as charlists.

# Summary

## Functions

Checks if list is a charlist made only of printable ASCII characters.

Deletes the given element from the list. Returns a new list without the element.

Produces a new list by removing the value at the specified index.

Duplicates the given element n times in a list.

Returns the first element in list or default if list is empty.

Flattens the given list of nested lists.

Flattens the given list of nested lists. The list tail will be added at the end of the flattened list.

Folds (reduces) the given list from the left with a function. Requires an accumulator, which can be any value.

Folds (reduces) the given list from the right with a function. Requires an accumulator, which can be any value.

Returns true if list is an improper list. Otherwise returns false.

Returns a list with value inserted at the specified index.

Receives a list of tuples and deletes the first tuple where the element at position matches the given key. Returns the new list.

Receives a list of tuples and returns the first tuple where the element at position in the tuple matches the given key.

Receives a list of tuples and returns the first tuple where the element at position in the tuple matches the given key.

Receives a list of tuples and returns true if there is a tuple where the element at position in the tuple matches the given key.

Receives a list of tuples and if the identified element by key at position exists, it is replaced with new_tuple.

Receives a list of tuples and sorts the elements at position of the tuples.

Receives a list of tuples and replaces the element identified by key at position with new_tuple.

Receives a list of tuples and returns the first tuple where the element at position in the tuple matches the given key, as well as the list without found tuple.

Returns the last element in list or default if list is empty.

Returns a keyword list that represents an edit script.

Returns a keyword list that represents an edit script with nested diffs.

Returns and removes the value at the specified index in the list.

Returns a list with a replaced value at the specified index.

Returns true if list starts with the given prefix list; otherwise returns false.

Converts a charlist to an atom.

Converts a list of integers representing Unicode code points, lists or strings into a charlist.

Converts a charlist to an existing atom.

Returns the float whose text representation is charlist.

Returns an integer whose text representation is charlist.

Returns an integer whose text representation is charlist in base base.

Converts a list of integers representing code points, lists or strings into a string.

Converts a list to a tuple.

Returns a list with an updated value at the specified index.

Wraps term in a list if this is not list.

Zips corresponding elements from each list in list_of_lists.

# ascii_printable?(list, limit \\ :infinity)

View Source (since 1.6.0)
@spec ascii_printable?(list(), 0) :: true
@spec ascii_printable?([], limit) :: true when limit: :infinity | pos_integer()
@spec ascii_printable?([...], limit) :: boolean()
when limit: :infinity | pos_integer()

Checks if list is a charlist made only of printable ASCII characters.

Takes an optional limit as a second argument. ascii_printable?/2 only checks the printability of the list up to the limit.

A printable charlist in Elixir contains only the printable characters in the standard seven-bit ASCII character encoding, which are characters ranging from 32 to 126 in decimal notation, plus the following control characters:

• ?\a - Bell
• ?\b - Backspace
• ?\t - Horizontal tab
• ?\n - Line feed
• ?\v - Vertical tab
• ?\f - Form feed
• ?\r - Carriage return
• ?\e - Escape

## Examples

iex> List.ascii_printable?(~c"abc")
true

iex> List.ascii_printable?(~c"abc" ++ [0])
false

iex> List.ascii_printable?(~c"abc" ++ [0], 2)
true

Improper lists are not printable, even if made only of ASCII characters:

iex> List.ascii_printable?(~c"abc" ++ ?d)
false

# delete(list, element)

View Source
@spec delete([], any()) :: []
@spec delete([...], any()) :: list()

Deletes the given element from the list. Returns a new list without the element.

If the element occurs more than once in the list, just the first occurrence is removed.

## Examples

iex> List.delete([:a, :b, :c], :a)
[:b, :c]

iex> List.delete([:a, :b, :c], :d)
[:a, :b, :c]

iex> List.delete([:a, :b, :b, :c], :b)
[:a, :b, :c]

iex> List.delete([], :b)
[]

# delete_at(list, index)

View Source
@spec delete_at(list(), integer()) :: list()

Produces a new list by removing the value at the specified index.

Negative indices indicate an offset from the end of the list. If index is out of bounds, the original list is returned.

## Examples

iex> List.delete_at([1, 2, 3], 0)
[2, 3]

iex> List.delete_at([1, 2, 3], 10)
[1, 2, 3]

iex> List.delete_at([1, 2, 3], -1)
[1, 2]

# duplicate(elem, n)

View Source
@spec duplicate(any(), 0) :: []
@spec duplicate(elem, pos_integer()) :: [elem, ...] when elem: var

Duplicates the given element n times in a list.

n is an integer greater than or equal to 0.

If n is 0, an empty list is returned.

## Examples

iex> List.duplicate("hello", 0)
[]

iex> List.duplicate("hi", 1)
["hi"]

iex> List.duplicate("bye", 2)
["bye", "bye"]

iex> List.duplicate([1, 2], 3)
[[1, 2], [1, 2], [1, 2]]

# first(list, default \\ nil)

View Source
@spec first([], any()) :: any()
@spec first([elem, ...], any()) :: elem when elem: var

Returns the first element in list or default if list is empty.

first/2 has been introduced in Elixir v1.12.0, while first/1 has been available since v1.0.0.

## Examples

iex> List.first([])
nil

iex> List.first([], 1)
1

iex> List.first([1])
1

iex> List.first([1, 2, 3])
1

# flatten(list)

View Source
@spec flatten(deep_list) :: list() when deep_list: [any() | deep_list]

Flattens the given list of nested lists.

## Examples

iex> List.flatten([1, [[2], 3]])
[1, 2, 3]

iex> List.flatten([[], [[], []]])
[]

# flatten(list, tail)

View Source
@spec flatten(deep_list, [elem]) :: [elem]
when deep_list: [elem | deep_list], elem: var

Flattens the given list of nested lists. The list tail will be added at the end of the flattened list.

Empty list elements from list are discarded, but not the ones from tail.

## Examples

iex> List.flatten([1, [[2], 3]], [4, 5])
[1, 2, 3, 4, 5]

iex> List.flatten([1, [], 2], [3, [], 4])
[1, 2, 3, [], 4]

# foldl(list, acc, fun)

View Source
@spec foldl([elem], acc, (elem, acc -> acc)) :: acc when elem: var, acc: var

Folds (reduces) the given list from the left with a function. Requires an accumulator, which can be any value.

## Examples

iex> List.foldl([5, 5], 10, fn x, acc -> x + acc end)
20

iex> List.foldl([1, 2, 3, 4], 0, fn x, acc -> x - acc end)
2

iex> List.foldl([1, 2, 3], {0, 0}, fn x, {a1, a2} -> {a1 + x, a2 - x} end)
{6, -6}

# foldr(list, acc, fun)

View Source
@spec foldr([elem], acc, (elem, acc -> acc)) :: acc when elem: var, acc: var

Folds (reduces) the given list from the right with a function. Requires an accumulator, which can be any value.

## Examples

iex> List.foldr([1, 2, 3, 4], 0, fn x, acc -> x - acc end)
-2

iex> List.foldr([1, 2, 3, 4], %{sum: 0, product: 1}, fn x, %{sum: a1, product: a2} -> %{sum: a1 + x, product: a2 * x} end)
%{product: 24, sum: 10}

# improper?(list)

View Source (since 1.8.0)
@spec improper?(maybe_improper_list()) :: boolean()

Returns true if list is an improper list. Otherwise returns false.

## Examples

iex> List.improper?([1, 2 | 3])
true

iex> List.improper?([1, 2, 3])
false

# insert_at(list, index, value)

View Source
@spec insert_at(list(), integer(), any()) :: list()

Returns a list with value inserted at the specified index.

Note that index is capped at the list length. Negative indices indicate an offset from the end of the list.

## Examples

iex> List.insert_at([1, 2, 3, 4], 2, 0)
[1, 2, 0, 3, 4]

iex> List.insert_at([1, 2, 3], 10, 0)
[1, 2, 3, 0]

iex> List.insert_at([1, 2, 3], -1, 0)
[1, 2, 3, 0]

iex> List.insert_at([1, 2, 3], -10, 0)
[0, 1, 2, 3]

# keydelete(list, key, position)

View Source
@spec keydelete([tuple()], any(), non_neg_integer()) :: [tuple()]

Receives a list of tuples and deletes the first tuple where the element at position matches the given key. Returns the new list.

## Examples

iex> List.keydelete([a: 1, b: 2], :a, 0)
[b: 2]

iex> List.keydelete([a: 1, b: 2], 2, 1)
[a: 1]

iex> List.keydelete([a: 1, b: 2], :c, 0)
[a: 1, b: 2]

This function works for any list of tuples:

iex> List.keydelete([{22, "SSH"}, {80, "HTTP"}], 80, 0)
[{22, "SSH"}]

# keyfind(list, key, position, default \\ nil)

View Source
@spec keyfind([tuple()], any(), non_neg_integer(), any()) :: any()

Receives a list of tuples and returns the first tuple where the element at position in the tuple matches the given key.

If no matching tuple is found, default is returned.

## Examples

iex> List.keyfind([a: 1, b: 2], :a, 0)
{:a, 1}

iex> List.keyfind([a: 1, b: 2], 2, 1)
{:b, 2}

iex> List.keyfind([a: 1, b: 2], :c, 0)
nil

This function works for any list of tuples:

iex> List.keyfind([{22, "SSH"}, {80, "HTTP"}], 22, 0)
{22, "SSH"}

# keyfind!(list, key, position)

View Source (since 1.13.0)
@spec keyfind!([tuple()], any(), non_neg_integer()) :: any()

Receives a list of tuples and returns the first tuple where the element at position in the tuple matches the given key.

If no matching tuple is found, an error is raised.

## Examples

iex> List.keyfind!([a: 1, b: 2], :a, 0)
{:a, 1}

iex> List.keyfind!([a: 1, b: 2], 2, 1)
{:b, 2}

iex> List.keyfind!([a: 1, b: 2], :c, 0)
** (KeyError) key :c at position 0 not found in: [a: 1, b: 2]

This function works for any list of tuples:

iex> List.keyfind!([{22, "SSH"}, {80, "HTTP"}], 22, 0)
{22, "SSH"}

# keymember?(list, key, position)

View Source
@spec keymember?([tuple()], any(), non_neg_integer()) :: boolean()

Receives a list of tuples and returns true if there is a tuple where the element at position in the tuple matches the given key.

## Examples

iex> List.keymember?([a: 1, b: 2], :a, 0)
true

iex> List.keymember?([a: 1, b: 2], 2, 1)
true

iex> List.keymember?([a: 1, b: 2], :c, 0)
false

This function works for any list of tuples:

iex> List.keymember?([{22, "SSH"}, {80, "HTTP"}], 22, 0)
true

# keyreplace(list, key, position, new_tuple)

View Source
@spec keyreplace([tuple()], any(), non_neg_integer(), tuple()) :: [tuple()]

Receives a list of tuples and if the identified element by key at position exists, it is replaced with new_tuple.

## Examples

iex> List.keyreplace([a: 1, b: 2], :a, 0, {:a, 3})
[a: 3, b: 2]

iex> List.keyreplace([a: 1, b: 2], :a, 1, {:a, 3})
[a: 1, b: 2]

This function works for any list of tuples:

iex> List.keyreplace([{22, "SSH"}, {80, "HTTP"}], 22, 0, {22, "Secure Shell"})
[{22, "Secure Shell"}, {80, "HTTP"}]

# keysort(list, position, sorter \\ :asc)

View Source (since 1.14.0)
@spec keysort(
[tuple()],
non_neg_integer(),
(any(), any() -> boolean())
| :asc
| :desc
| module()
| {:asc | :desc, module()}
) :: [tuple()]

Receives a list of tuples and sorts the elements at position of the tuples.

The sort is stable.

A sorter argument is available since Elixir v1.14.0. Similar to Enum.sort/2, the sorter can be an anonymous function, the atoms :asc or :desc, or module that implements a compare function.

## Examples

iex> List.keysort([a: 5, b: 1, c: 3], 1)
[b: 1, c: 3, a: 5]

iex> List.keysort([a: 5, c: 1, b: 3], 0)
[a: 5, b: 3, c: 1]

To sort in descending order:

iex> List.keysort([a: 5, c: 1, b: 3], 0, :desc)
[c: 1, b: 3, a: 5]

As in Enum.sort/2, avoid using the default sorting function to sort structs, as by default it performs structural comparison instead of a semantic one. In such cases, you shall pass a sorting function as third element or any module that implements a compare/2 function. For example, if you have tuples with user names and their birthday, and you want to sort on their birthday, in both ascending and descending order, you should do:

iex> users = [
...>   {"Ellis", ~D[1943-05-11]},
...>   {"Lovelace", ~D[1815-12-10]},
...>   {"Turing", ~D[1912-06-23]}
...> ]
iex> List.keysort(users, 1, Date)
[
{"Lovelace", ~D[1815-12-10]},
{"Turing", ~D[1912-06-23]},
{"Ellis", ~D[1943-05-11]}
]
iex> List.keysort(users, 1, {:desc, Date})
[
{"Ellis", ~D[1943-05-11]},
{"Turing", ~D[1912-06-23]},
{"Lovelace", ~D[1815-12-10]}
]

# keystore(list, key, position, new_tuple)

View Source
@spec keystore([tuple()], any(), non_neg_integer(), tuple()) :: [tuple(), ...]

Receives a list of tuples and replaces the element identified by key at position with new_tuple.

If the element does not exist, it is added to the end of the list.

## Examples

iex> List.keystore([a: 1, b: 2], :a, 0, {:a, 3})
[a: 3, b: 2]

iex> List.keystore([a: 1, b: 2], :c, 0, {:c, 3})
[a: 1, b: 2, c: 3]

This function works for any list of tuples:

iex> List.keystore([{22, "SSH"}], 80, 0, {80, "HTTP"})
[{22, "SSH"}, {80, "HTTP"}]

# keytake(list, key, position)

View Source
@spec keytake([tuple()], any(), non_neg_integer()) :: {tuple(), [tuple()]} | nil

Receives a list of tuples and returns the first tuple where the element at position in the tuple matches the given key, as well as the list without found tuple.

## Examples

iex> List.keytake([a: 1, b: 2], :a, 0)
{{:a, 1}, [b: 2]}

iex> List.keytake([a: 1, b: 2], 2, 1)
{{:b, 2}, [a: 1]}

iex> List.keytake([a: 1, b: 2], :c, 0)
nil

This function works for any list of tuples:

iex> List.keytake([{22, "SSH"}, {80, "HTTP"}], 80, 0)
{{80, "HTTP"}, [{22, "SSH"}]}

# last(list, default \\ nil)

View Source
@spec last([], any()) :: any()
@spec last([elem, ...], any()) :: elem when elem: var

Returns the last element in list or default if list is empty.

last/2 has been introduced in Elixir v1.12.0, while last/1 has been available since v1.0.0.

## Examples

iex> List.last([])
nil

iex> List.last([], 1)
1

iex> List.last([1])
1

iex> List.last([1, 2, 3])
3

# myers_difference(list1, list2)

View Source (since 1.4.0)
@spec myers_difference(list(), list()) :: [{:eq | :ins | :del, list()}]

Returns a keyword list that represents an edit script.

The algorithm is outlined in the "An O(ND) Difference Algorithm and Its Variations" paper by E. Myers.

An edit script is a keyword list. Each key describes the "editing action" to take in order to bring list1 closer to being equal to list2; a key can be :eq, :ins, or :del. Each value is a sublist of either list1 or list2 that should be inserted (if the corresponding key :ins), deleted (if the corresponding key is :del), or left alone (if the corresponding key is :eq) in list1 in order to be closer to list2.

See myers_difference/3 if you want to handle nesting in the diff scripts.

## Examples

iex> List.myers_difference([1, 4, 2, 3], [1, 2, 3, 4])
[eq: [1], del: [4], eq: [2, 3], ins: [4]]

# myers_difference(list1, list2, diff_script)

View Source (since 1.8.0)
@spec myers_difference(list(), list(), (term(), term() -> script | nil)) :: script
when script: [{:eq | :ins | :del | :diff, list()}]

Returns a keyword list that represents an edit script with nested diffs.

This is an extension of myers_difference/2 where a diff_script function can be given in case it is desired to compute nested differences. The function may return a list with the inner edit script or nil in case there is no such script. The returned inner edit script will be under the :diff key.

## Examples

iex> List.myers_difference(["a", "db", "c"], ["a", "bc"], &String.myers_difference/2)
[eq: ["a"], diff: [del: "d", eq: "b", ins: "c"], del: ["c"]]

# pop_at(list, index, default \\ nil)

View Source (since 1.4.0)
@spec pop_at(list(), integer(), any()) :: {any(), list()}

Returns and removes the value at the specified index in the list.

Negative indices indicate an offset from the end of the list. If index is out of bounds, the original list is returned.

## Examples

iex> List.pop_at([1, 2, 3], 0)
{1, [2, 3]}
iex> List.pop_at([1, 2, 3], 5)
{nil, [1, 2, 3]}
iex> List.pop_at([1, 2, 3], 5, 10)
{10, [1, 2, 3]}
iex> List.pop_at([1, 2, 3], -1)
{3, [1, 2]}

# replace_at(list, index, value)

View Source
@spec replace_at(list(), integer(), any()) :: list()

Returns a list with a replaced value at the specified index.

Negative indices indicate an offset from the end of the list. If index is out of bounds, the original list is returned.

## Examples

iex> List.replace_at([1, 2, 3], 0, 0)
[0, 2, 3]

iex> List.replace_at([1, 2, 3], 10, 0)
[1, 2, 3]

iex> List.replace_at([1, 2, 3], -1, 0)
[1, 2, 0]

iex> List.replace_at([1, 2, 3], -10, 0)
[1, 2, 3]

# starts_with?(list, prefix)

View Source (since 1.5.0)
@spec starts_with?([...], [...]) :: boolean()
@spec starts_with?(list(), []) :: true
@spec starts_with?([], [...]) :: false

Returns true if list starts with the given prefix list; otherwise returns false.

If prefix is an empty list, it returns true.

### Examples

iex> List.starts_with?([1, 2, 3], [1, 2])
true

iex> List.starts_with?([1, 2], [1, 2, 3])
false

iex> List.starts_with?([:alpha], [])
true

iex> List.starts_with?([], [:alpha])
false

# to_atom(charlist)

View Source
@spec to_atom(charlist()) :: atom()

Converts a charlist to an atom.

Elixir supports conversions from charlists which contains any Unicode code point.

Inlined by the compiler.

## Examples

iex> List.to_atom(~c"Elixir")
:Elixir

iex> List.to_atom(~c"🌢 Elixir")
:"🌢 Elixir"

# to_charlist(list)

View Source (since 1.8.0)
@spec to_charlist(:unicode.charlist()) :: charlist()

Converts a list of integers representing Unicode code points, lists or strings into a charlist.

Note that this function expects a list of integers representing Unicode code points. If you have a list of bytes, you must instead use the :binary module.

## Examples

iex> ~c"æß" = List.to_charlist([0x00E6, 0x00DF])
[230, 223]

iex> List.to_charlist([0x0061, "bc"])
~c"abc"

iex> List.to_charlist([0x0064, "ee", [~c"p"]])
~c"deep"

# to_existing_atom(charlist)

View Source
@spec to_existing_atom(charlist()) :: atom()

Converts a charlist to an existing atom.

Elixir supports conversions from charlists which contains any Unicode code point. Raises an ArgumentError if the atom does not exist.

Inlined by the compiler.

#### Atoms and modules

Since Elixir is a compiled language, the atoms defined in a module will only exist after said module is loaded, which typically happens whenever a function in the module is executed. Therefore, it is generally recommended to call List.to_existing_atom/1 only to convert atoms defined within the module making the function call to to_existing_atom/1.

## Examples

iex> _ = :my_atom
iex> List.to_existing_atom(~c"my_atom")
:my_atom

iex> _ = :"🌢 Elixir"
iex> List.to_existing_atom(~c"🌢 Elixir")
:"🌢 Elixir"

# to_float(charlist)

View Source
@spec to_float(charlist()) :: float()

Returns the float whose text representation is charlist.

Inlined by the compiler.

## Examples

iex> List.to_float(~c"2.2017764e+0")
2.2017764

# to_integer(charlist)

View Source
@spec to_integer(charlist()) :: integer()

Returns an integer whose text representation is charlist.

Inlined by the compiler.

## Examples

iex> List.to_integer(~c"123")
123

# to_integer(charlist, base)

View Source
@spec to_integer(
charlist(),
2..36
) :: integer()

Returns an integer whose text representation is charlist in base base.

Inlined by the compiler.

The base needs to be between 2 and 36.

## Examples

iex> List.to_integer(~c"3FF", 16)
1023

# to_string(list)

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@spec to_string(:unicode.charlist()) :: String.t()

Converts a list of integers representing code points, lists or strings into a string.

To be converted to a string, a list must either be empty or only contain the following elements:

• strings
• integers representing Unicode code points
• a list containing one of these three elements

Note that this function expects a list of integers representing Unicode code points. If you have a list of bytes, you must instead use the :binary module.

## Examples

iex> List.to_string([0x00E6, 0x00DF])
"æß"

iex> List.to_string([0x0061, "bc"])
"abc"

iex> List.to_string([0x0064, "ee", [~c"p"]])
"deep"

iex> List.to_string([])
""

# to_tuple(list)

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@spec to_tuple(list()) :: tuple()

Converts a list to a tuple.

Inlined by the compiler.

## Examples

iex> List.to_tuple([:share, [:elixir, 163]])
{:share, [:elixir, 163]}

# update_at(list, index, fun)

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@spec update_at([elem], integer(), (elem -> any())) :: list() when elem: var

Returns a list with an updated value at the specified index.

Negative indices indicate an offset from the end of the list. If index is out of bounds, the original list is returned.

## Examples

iex> List.update_at([1, 2, 3], 0, &(&1 + 10))
[11, 2, 3]

iex> List.update_at([1, 2, 3], 10, &(&1 + 10))
[1, 2, 3]

iex> List.update_at([1, 2, 3], -1, &(&1 + 10))
[1, 2, 13]

iex> List.update_at([1, 2, 3], -10, &(&1 + 10))
[1, 2, 3]

# wrap(term)

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@spec wrap(term()) :: maybe_improper_list()

Wraps term in a list if this is not list.

If term is already a list, it returns the list. If term is nil, it returns an empty list.

## Examples

iex> List.wrap("hello")
["hello"]

iex> List.wrap([1, 2, 3])
[1, 2, 3]

iex> List.wrap(nil)
[]

# zip(list_of_lists)

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@spec zip([list()]) :: [tuple()]

Zips corresponding elements from each list in list_of_lists.

The zipping finishes as soon as any list terminates.

## Examples

iex> List.zip([[1, 2], [3, 4], [5, 6]])
[{1, 3, 5}, {2, 4, 6}]

iex> List.zip([[1, 2], [3], [5, 6]])
[{1, 3, 5}]