Elixir v1.7.2 Tuple View Source

Functions for working with tuples.

Please note the following functions for tuples are found in Kernel:

Tuples are intended as fixed-size containers for multiple elements. To manipulate a collection of elements, use a list instead. Enum functions do not work on tuples.

Tuples are denoted with curly braces:

iex> {}
{}
iex> {1, :two, "three"}
{1, :two, "three"}

A tuple may contain elements of different types, which are stored contiguously in memory. Accessing any element takes constant time, but modifying a tuple, which produces a shallow copy, takes linear time. Tuples are good for reading data while lists are better for traversals.

Tuples are typically used either when a function has multiple return values or for error handling. File.read/1 returns {:ok, contents} if reading the given file is successful, or else {:error, reason} such as when the file does not exist.

The functions in this module that add and remove elements from tuples are rarely used in practice, as they typically imply tuples are being used as collections. To append to a tuple, it is preferrable to use pattern matching:

tuple = {:ok, :example}

# Avoid
Tuple.insert_at(tuple, 2, %{}}

# Prefer
{:ok, atom} = tuple
{:ok, atom, %{}}

Link to this section Summary

Functions

Inserts an element at the end of a tuple

Removes an element from a tuple

Creates a new tuple

Inserts an element into a tuple

Converts a tuple to a list

Link to this section Functions

Link to this function append(tuple, value) View Source
append(tuple(), term()) :: tuple()

Inserts an element at the end of a tuple.

Returns a new tuple with the element appended at the end, and contains the elements in tuple followed by value as the last element.

Inlined by the compiler.

Examples

iex> tuple = {:foo, :bar}
iex> Tuple.append(tuple, :baz)
{:foo, :bar, :baz}
Link to this function delete_at(tuple, index) View Source
delete_at(tuple(), non_neg_integer()) :: tuple()

Removes an element from a tuple.

Deletes the element at the given index from tuple. Raises an ArgumentError if index is negative or greater than or equal to the length of tuple. Index is zero-based.

Inlined by the compiler.

Examples

iex> tuple = {:foo, :bar, :baz}
iex> Tuple.delete_at(tuple, 0)
{:bar, :baz}
Link to this function duplicate(data, size) View Source
duplicate(term(), non_neg_integer()) :: tuple()

Creates a new tuple.

Creates a tuple of size containing the given data at every position.

Inlined by the compiler.

Examples

iex> Tuple.duplicate(:hello, 3)
{:hello, :hello, :hello}
Link to this function insert_at(tuple, index, value) View Source
insert_at(tuple(), non_neg_integer(), term()) :: tuple()

Inserts an element into a tuple.

Inserts value into tuple at the given index. Raises an ArgumentError if index is negative or greater than the length of tuple. Index is zero-based.

Inlined by the compiler.

Examples

iex> tuple = {:bar, :baz}
iex> Tuple.insert_at(tuple, 0, :foo)
{:foo, :bar, :baz}
iex> Tuple.insert_at(tuple, 2, :bong)
{:bar, :baz, :bong}
Link to this function to_list(tuple) View Source
to_list(tuple()) :: list()

Converts a tuple to a list.

Returns a new list with all the tuple elements.

Inlined by the compiler.

Examples

iex> tuple = {:foo, :bar, :baz}
iex> Tuple.to_list(tuple)
[:foo, :bar, :baz]