# Chapter 12. Tuples

This chapter presents one more built-in type, the tuple, and then shows how arrays, dictionaries, and tuples work together. It also introduces a useful feature for variable-length argument arrays, the gather and scatter operators.

# Tuples Are Immutable

A tuple is a sequence of values. The values can be of any type, and they are indexed by integers, so in that respect tuples are a lot like arrays. The important difference is that tuples are immutable and that each element can have its own type.

Syntactically, a tuple is a comma-separated list of values:

````julia>` `t` `=` `'a'``,` `'b'``,` `'c'``,` `'d'``,` `'e'`
`('a', 'b', 'c', 'd', 'e')````

Although it is not necessary, it is common to enclose tuples in parentheses:

````julia>` `t` `=` `(``'a'``,` `'b'``,` `'c'``,` `'d'``,` `'e'``)`
`('a', 'b', 'c', 'd', 'e')````

To create a tuple with a single element, you have to include a final comma:

````julia>` `t1` `=` `(``'a'``,)`
`('a',)`
`julia>` `typeof``(``t1``)`
`Tuple{Char}````

A value in parentheses without comma is not a tuple:

````julia>` `t2` `=` `(``'a'``)`
`'a': ASCII/Unicode U+0061 (category Ll: Letter,`
`  lowercase)`
`julia>` `typeof``(``t2``)`
`Char````

Another way to create a tuple is using the built-in function `tuple`. With no argument, it creates an empty tuple:

````julia>` `tuple``()`
`()````

If multiple arguments are provided, the result is a tuple with the given arguments:

````julia>` `t3` `=` `tuple``(``1``,` `'a'``,` `pi``)`
`(1, 'a', π = 3.1415926535897...)````

Because `tuple` is the name of a built-in function, you should avoid using it as a variable name.

Most array operators also work on tuples. The bracket operator ...

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