# 1.12.0[−][src]Trait std::iter::Sum

    pub trait Sum<A = Self> {
        fn sum<I>(iter: I) -> Self
        where
            I: Iterator<Item = A>;
    }

Trait to represent types that can be created by summing up an iterator.

This trait is used to implement the `sum` method on iterators. Types which implement the trait can be generated by the `sum` method. Like `FromIterator` this trait should rarely be called directly and instead interacted with through `Iterator::sum`.

## Required methods

### `fn sum<I>(iter: I) -> Self where
I: Iterator<Item = A>,`

Method which takes an iterator and generates `Self` from the elements by "summing up" the items.

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## Implementors

### `impl Sum<f32> for f32`[src]

#### `fn sum<I>(iter: I) -> f32 where
I: Iterator<Item = f32>,` [src]

### `impl Sum<f64> for f64`[src]

#### `fn sum<I>(iter: I) -> f64 where
I: Iterator<Item = f64>,` [src]

### `impl Sum<i128> for i128`[src]

#### `fn sum<I>(iter: I) -> i128 where
I: Iterator<Item = i128>,` [src]

### `impl Sum<i16> for i16`[src]

#### `fn sum<I>(iter: I) -> i16 where
I: Iterator<Item = i16>,` [src]

### `impl Sum<i32> for i32`[src]

#### `fn sum<I>(iter: I) -> i32 where
I: Iterator<Item = i32>,` [src]

### `impl Sum<i64> for i64`[src]

#### `fn sum<I>(iter: I) -> i64 where
I: Iterator<Item = i64>,` [src]

### `impl Sum<i8> for i8`[src]

#### `fn sum<I>(iter: I) -> i8 where
I: Iterator<Item = i8>,` [src]

### `impl Sum<isize> for isize`[src]

#### `fn sum<I>(iter: I) -> isize where
I: Iterator<Item = isize>,` [src]

### `impl Sum<u128> for u128`[src]

#### `fn sum<I>(iter: I) -> u128 where
I: Iterator<Item = u128>,` [src]

### `impl Sum<u16> for u16`[src]

#### `fn sum<I>(iter: I) -> u16 where
I: Iterator<Item = u16>,` [src]

### `impl Sum<u32> for u32`[src]

#### `fn sum<I>(iter: I) -> u32 where
I: Iterator<Item = u32>,` [src]

### `impl Sum<u64> for u64`[src]

#### `fn sum<I>(iter: I) -> u64 where
I: Iterator<Item = u64>,` [src]

### `impl Sum<u8> for u8`[src]

#### `fn sum<I>(iter: I) -> u8 where
I: Iterator<Item = u8>,` [src]

### `impl Sum<usize> for usize`[src]

#### `fn sum<I>(iter: I) -> usize where
I: Iterator<Item = usize>,` [src]

### `impl Sum<Wrapping<i128>> for Wrapping<i128>`[src]

#### `fn sum<I>(iter: I) -> Wrapping<i128> where
I: Iterator<Item = Wrapping<i128>>,` [src]

### `impl Sum<Wrapping<i16>> for Wrapping<i16>`[src]

#### `fn sum<I>(iter: I) -> Wrapping<i16> where
I: Iterator<Item = Wrapping<i16>>,` [src]

### `impl Sum<Wrapping<i32>> for Wrapping<i32>`[src]

#### `fn sum<I>(iter: I) -> Wrapping<i32> where
I: Iterator<Item = Wrapping<i32>>,` [src]

### `impl Sum<Wrapping<i64>> for Wrapping<i64>`[src]

#### `fn sum<I>(iter: I) -> Wrapping<i64> where
I: Iterator<Item = Wrapping<i64>>,` [src]

### `impl Sum<Wrapping<i8>> for Wrapping<i8>`[src]

#### `fn sum<I>(iter: I) -> Wrapping<i8> where
I: Iterator<Item = Wrapping<i8>>,` [src]

### `impl Sum<Wrapping<isize>> for Wrapping<isize>`[src]

#### `fn sum<I>(iter: I) -> Wrapping<isize> where
I: Iterator<Item = Wrapping<isize>>,` [src]

### `impl Sum<Wrapping<u128>> for Wrapping<u128>`[src]

#### `fn sum<I>(iter: I) -> Wrapping<u128> where
I: Iterator<Item = Wrapping<u128>>,` [src]

### `impl Sum<Wrapping<u16>> for Wrapping<u16>`[src]

#### `fn sum<I>(iter: I) -> Wrapping<u16> where
I: Iterator<Item = Wrapping<u16>>,` [src]

### `impl Sum<Wrapping<u32>> for Wrapping<u32>`[src]

#### `fn sum<I>(iter: I) -> Wrapping<u32> where
I: Iterator<Item = Wrapping<u32>>,` [src]

### `impl Sum<Wrapping<u64>> for Wrapping<u64>`[src]

#### `fn sum<I>(iter: I) -> Wrapping<u64> where
I: Iterator<Item = Wrapping<u64>>,` [src]

### `impl Sum<Wrapping<u8>> for Wrapping<u8>`[src]

#### `fn sum<I>(iter: I) -> Wrapping<u8> where
I: Iterator<Item = Wrapping<u8>>,` [src]

### `impl Sum<Wrapping<usize>> for Wrapping<usize>`[src]

#### `fn sum<I>(iter: I) -> Wrapping<usize> where
I: Iterator<Item = Wrapping<usize>>,` [src]

### `impl Sum<Duration> for Duration`[src]

#### `fn sum<I>(iter: I) -> Duration where
I: Iterator<Item = Duration>,` [src]

### `impl<'a> Sum<&'a f32> for f32`[src]

#### `fn sum<I>(iter: I) -> f32 where
I: Iterator<Item = &'a f32>,` [src]

### `impl<'a> Sum<&'a f64> for f64`[src]

#### `fn sum<I>(iter: I) -> f64 where
I: Iterator<Item = &'a f64>,` [src]

### `impl<'a> Sum<&'a i128> for i128`[src]

#### `fn sum<I>(iter: I) -> i128 where
I: Iterator<Item = &'a i128>,` [src]

### `impl<'a> Sum<&'a i16> for i16`[src]

#### `fn sum<I>(iter: I) -> i16 where
I: Iterator<Item = &'a i16>,` [src]

### `impl<'a> Sum<&'a i32> for i32`[src]

#### `fn sum<I>(iter: I) -> i32 where
I: Iterator<Item = &'a i32>,` [src]

### `impl<'a> Sum<&'a i64> for i64`[src]

#### `fn sum<I>(iter: I) -> i64 where
I: Iterator<Item = &'a i64>,` [src]

### `impl<'a> Sum<&'a i8> for i8`[src]

#### `fn sum<I>(iter: I) -> i8 where
I: Iterator<Item = &'a i8>,` [src]

### `impl<'a> Sum<&'a isize> for isize`[src]

#### `fn sum<I>(iter: I) -> isize where
I: Iterator<Item = &'a isize>,` [src]

### `impl<'a> Sum<&'a u128> for u128`[src]

#### `fn sum<I>(iter: I) -> u128 where
I: Iterator<Item = &'a u128>,` [src]

### `impl<'a> Sum<&'a u16> for u16`[src]

#### `fn sum<I>(iter: I) -> u16 where
I: Iterator<Item = &'a u16>,` [src]

### `impl<'a> Sum<&'a u32> for u32`[src]

#### `fn sum<I>(iter: I) -> u32 where
I: Iterator<Item = &'a u32>,` [src]

### `impl<'a> Sum<&'a u64> for u64`[src]

#### `fn sum<I>(iter: I) -> u64 where
I: Iterator<Item = &'a u64>,` [src]

### `impl<'a> Sum<&'a u8> for u8`[src]

#### `fn sum<I>(iter: I) -> u8 where
I: Iterator<Item = &'a u8>,` [src]

### `impl<'a> Sum<&'a usize> for usize`[src]

#### `fn sum<I>(iter: I) -> usize where
I: Iterator<Item = &'a usize>,` [src]

### `impl<'a> Sum<&'a Wrapping<i128>> for Wrapping<i128>`[src]

#### `fn sum<I>(iter: I) -> Wrapping<i128> where
I: Iterator<Item = &'a Wrapping<i128>>,` [src]

### `impl<'a> Sum<&'a Wrapping<i16>> for Wrapping<i16>`[src]

#### `fn sum<I>(iter: I) -> Wrapping<i16> where
I: Iterator<Item = &'a Wrapping<i16>>,` [src]

### `impl<'a> Sum<&'a Wrapping<i32>> for Wrapping<i32>`[src]

#### `fn sum<I>(iter: I) -> Wrapping<i32> where
I: Iterator<Item = &'a Wrapping<i32>>,` [src]

### `impl<'a> Sum<&'a Wrapping<i64>> for Wrapping<i64>`[src]

#### `fn sum<I>(iter: I) -> Wrapping<i64> where
I: Iterator<Item = &'a Wrapping<i64>>,` [src]

### `impl<'a> Sum<&'a Wrapping<i8>> for Wrapping<i8>`[src]

#### `fn sum<I>(iter: I) -> Wrapping<i8> where
I: Iterator<Item = &'a Wrapping<i8>>,` [src]

### `impl<'a> Sum<&'a Wrapping<isize>> for Wrapping<isize>`[src]

#### `fn sum<I>(iter: I) -> Wrapping<isize> where
I: Iterator<Item = &'a Wrapping<isize>>,` [src]

### `impl<'a> Sum<&'a Wrapping<u128>> for Wrapping<u128>`[src]

#### `fn sum<I>(iter: I) -> Wrapping<u128> where
I: Iterator<Item = &'a Wrapping<u128>>,` [src]

### `impl<'a> Sum<&'a Wrapping<u16>> for Wrapping<u16>`[src]

#### `fn sum<I>(iter: I) -> Wrapping<u16> where
I: Iterator<Item = &'a Wrapping<u16>>,` [src]

### `impl<'a> Sum<&'a Wrapping<u32>> for Wrapping<u32>`[src]

#### `fn sum<I>(iter: I) -> Wrapping<u32> where
I: Iterator<Item = &'a Wrapping<u32>>,` [src]

### `impl<'a> Sum<&'a Wrapping<u64>> for Wrapping<u64>`[src]

#### `fn sum<I>(iter: I) -> Wrapping<u64> where
I: Iterator<Item = &'a Wrapping<u64>>,` [src]

### `impl<'a> Sum<&'a Wrapping<u8>> for Wrapping<u8>`[src]

#### `fn sum<I>(iter: I) -> Wrapping<u8> where
I: Iterator<Item = &'a Wrapping<u8>>,` [src]

### `impl<'a> Sum<&'a Wrapping<usize>> for Wrapping<usize>`[src]

#### `fn sum<I>(iter: I) -> Wrapping<usize> where
I: Iterator<Item = &'a Wrapping<usize>>,` [src]

### `impl<'a> Sum<&'a Duration> for Duration`[src]

#### `fn sum<I>(iter: I) -> Duration where
I: Iterator<Item = &'a Duration>,` [src]

### `impl<T, U> Sum<Option<U>> for Option<T> where
T: Sum<U>,` [src]

#### `fn sum<I>(iter: I) -> Option<T> where
I: Iterator<Item = Option<U>>,` [src]

Takes each element in the `Iterator`: if it is a `None`, no further elements are taken, and the `None` is returned. Should no `None` occur, the sum of all elements is returned.

# Examples

This sums up the position of the character 'a' in a vector of strings, if a word did not have the character 'a' the operation returns `None`:

    let words = vec!["have", "a", "great", "day"];
    let total: Option<usize> = words.iter().map(|w| w.find('a')).sum();
    assert_eq!(total, Some(5));

Run

### `impl<T, U, E> Sum<Result<U, E>> for Result<T, E> where
T: Sum<U>,` [src]

#### `fn sum<I>(iter: I) -> Result<T, E> where
I: Iterator<Item = Result<U, E>>,` [src]

Takes each element in the `Iterator`: if it is an `Err`, no further elements are taken, and the `Err` is returned. Should no `Err` occur, the sum of all elements is returned.

# Examples

This sums up every integer in a vector, rejecting the sum if a negative element is encountered:

    let v = vec![1, 2];
    let res: Result<i32, &'static str> = v.iter().map(|&x: &i32|
        if x < 0 { Err("Negative element found") }
        else { Ok(x) }
    ).sum();
    assert_eq!(res, Ok(3));

Run
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