# Primitive Type tuple

1.0.0 · []
Expand description

A finite heterogeneous sequence, `(T, U, ..)`.

Let’s cover each of those in turn:

Tuples are finite. In other words, a tuple has a length. Here’s a tuple of length `3`:

``("hello", 5, 'c');``
Run

‘Length’ is also sometimes called ‘arity’ here; each tuple of a different length is a different, distinct type.

Tuples are heterogeneous. This means that each element of the tuple can have a different type. In that tuple above, it has the type:

``(&'static str, i32, char)``
Run

Tuples are a sequence. This means that they can be accessed by position; this is called ‘tuple indexing’, and it looks like this:

``````let tuple = ("hello", 5, 'c');

assert_eq!(tuple.0, "hello");
assert_eq!(tuple.1, 5);
assert_eq!(tuple.2, 'c');``````
Run

The sequential nature of the tuple applies to its implementations of various traits. For example, in `PartialOrd` and `Ord`, the elements are compared sequentially until the first non-equal set is found.

For more about tuples, see the book.

## Trait implementations

In this documentation the shorthand `(T₁, T₂, …, Tₙ)` is used to represent tuples of varying length. When that is used, any trait bound expressed on `T` applies to each element of the tuple independently. Note that this is a convenience notation to avoid repetitive documentation, not valid Rust syntax.

Due to a temporary restriction in Rust’s type system, the following traits are only implemented on tuples of arity 12 or less. In the future, this may change:

The following traits are implemented for tuples of any length. These traits have implementations that are automatically generated by the compiler, so are not limited by missing language features.

## Examples

Basic usage:

``````let tuple = ("hello", 5, 'c');

assert_eq!(tuple.0, "hello");``````
Run

Tuples are often used as a return type when you want to return more than one value:

``````fn calculate_point() -> (i32, i32) {
// Don't do a calculation, that's not the point of the example
(4, 5)
}

let point = calculate_point();

assert_eq!(point.0, 4);
assert_eq!(point.1, 5);

// Combining this with patterns can be nicer.

let (x, y) = calculate_point();

assert_eq!(x, 4);
assert_eq!(y, 5);``````
Run

## Trait Implementations

This trait is implemented on arbitrary-length tuples.

Returns a copy of the value. Read more
Performs copy-assignment from `source`. Read more

This trait is implemented for tuples up to twelve items long.

Formats the value using the given formatter. Read more

This trait is implemented for tuples up to twelve items long.

Returns the “default value” for a type. Read more

Allows to `extend` a tuple of collections that also implement `Extend`.

See also: `Iterator::unzip`

##### Examples
``````let mut tuple = (vec![0], vec![1]);
tuple.extend([(2, 3), (4, 5), (6, 7)]);
assert_eq!(tuple.0, [0, 2, 4, 6]);
assert_eq!(tuple.1, [1, 3, 5, 7]);

// also allows for arbitrarily nested tuples as elements
let mut nested_tuple = (vec![1], (vec![2], vec![3]));
nested_tuple.extend([(4, (5, 6)), (7, (8, 9))]);

let (a, (b, c)) = nested_tuple;
assert_eq!(a, [1, 4, 7]);
assert_eq!(b, [2, 5, 8]);
assert_eq!(c, [3, 6, 9]);``````
Run
🔬This is a nightly-only experimental API. (`extend_one` #72631)
Extends a collection with exactly one element.
🔬This is a nightly-only experimental API. (`extend_one` #72631)
Reserves capacity in a collection for the given number of additional elements. Read more

This trait is implemented for tuples up to twelve items long.

Feeds this value into the given `Hasher`. Read more

This trait is implemented for tuples up to twelve items long.

This method returns an `Ordering` between `self` and `other`. Read more

This trait is implemented for tuples up to twelve items long.

This method tests for `self` and `other` values to be equal, and is used by `==`. Read more
This method tests for `!=`. The default implementation is almost always sufficient, and should not be overridden without very good reason. Read more

This trait is implemented for tuples up to twelve items long.

This method returns an ordering between `self` and `other` values if one exists. Read more
This method tests less than (for `self` and `other`) and is used by the `<` operator. Read more
This method tests less than or equal to (for `self` and `other`) and is used by the `<=` operator. Read more
This method tests greater than or equal to (for `self` and `other`) and is used by the `>=` operator. Read more
This method tests greater than (for `self` and `other`) and is used by the `>` operator. Read more
Returns `true` if `item` is contained in the range. Read more
Returns `true` if `item` is contained in the range. Read more
The output type returned by methods.
🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a shared reference to the output at this location, if in bounds. Read more
🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a mutable reference to the output at this location, if in bounds. Read more
🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a shared reference to the output at this location, without performing any bounds checking. Calling this method with an out-of-bounds index or a dangling `slice` pointer is undefined behavior even if the resulting reference is not used. Read more
🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a mutable reference to the output at this location, without performing any bounds checking. Calling this method with an out-of-bounds index or a dangling `slice` pointer is undefined behavior even if the resulting reference is not used. Read more
🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a shared reference to the output at this location, panicking if out of bounds. Read more
🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a mutable reference to the output at this location, panicking if out of bounds. Read more

This trait is implemented on arbitrary-length tuples.

This trait is implemented for tuples up to twelve items long.

## Blanket Implementations

Gets the `TypeId` of `self`. Read more
Immutably borrows from an owned value. Read more
Mutably borrows from an owned value. Read more

Returns the argument unchanged.

Calls `U::from(self)`.

That is, this conversion is whatever the implementation of `From<T> for U` chooses to do.

The type returned in the event of a conversion error.
Performs the conversion.
The type returned in the event of a conversion error.
Performs the conversion.