# Trait core::iter::Sum 1.12.0[−][src]

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

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: Iterator<Item = A>>(iter: I) -> Self`[src]

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

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## Implementors

### `impl Sum<Wrapping<i8>> for Wrapping<i8>`1.14.0[src]

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

### `impl Sum<Wrapping<i16>> for Wrapping<i16>`1.14.0[src]

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

### `impl Sum<Wrapping<i32>> for Wrapping<i32>`1.14.0[src]

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

### `impl Sum<Wrapping<i64>> for Wrapping<i64>`1.14.0[src]

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

### `impl Sum<Wrapping<i128>> for Wrapping<i128>`1.14.0[src]

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

### `impl Sum<Wrapping<isize>> for Wrapping<isize>`1.14.0[src]

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

### `impl Sum<Wrapping<u8>> for Wrapping<u8>`1.14.0[src]

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

### `impl Sum<Wrapping<u16>> for Wrapping<u16>`1.14.0[src]

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

### `impl Sum<Wrapping<u32>> for Wrapping<u32>`1.14.0[src]

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

### `impl Sum<Wrapping<u64>> for Wrapping<u64>`1.14.0[src]

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

### `impl Sum<Wrapping<u128>> for Wrapping<u128>`1.14.0[src]

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

### `impl Sum<Wrapping<usize>> for Wrapping<usize>`1.14.0[src]

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

### `impl Sum<Duration> for Duration` 1.16.0[src]

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

### `impl<'a> Sum<&'a Wrapping<i8>> for Wrapping<i8>`1.14.0[src]

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

### `impl<'a> Sum<&'a Wrapping<i16>> for Wrapping<i16>`1.14.0[src]

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

### `impl<'a> Sum<&'a Wrapping<i32>> for Wrapping<i32>`1.14.0[src]

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

### `impl<'a> Sum<&'a Wrapping<i64>> for Wrapping<i64>`1.14.0[src]

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

### `impl<'a> Sum<&'a Wrapping<i128>> for Wrapping<i128>`1.14.0[src]

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

### `impl<'a> Sum<&'a Wrapping<isize>> for Wrapping<isize>`1.14.0[src]

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

### `impl<'a> Sum<&'a Wrapping<u8>> for Wrapping<u8>`1.14.0[src]

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

### `impl<'a> Sum<&'a Wrapping<u16>> for Wrapping<u16>`1.14.0[src]

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

### `impl<'a> Sum<&'a Wrapping<u32>> for Wrapping<u32>`1.14.0[src]

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

### `impl<'a> Sum<&'a Wrapping<u64>> for Wrapping<u64>`1.14.0[src]

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

### `impl<'a> Sum<&'a Wrapping<u128>> for Wrapping<u128>`1.14.0[src]

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

### `impl<'a> Sum<&'a Wrapping<usize>> for Wrapping<usize>`1.14.0[src]

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

### `impl<'a> Sum<&'a Duration> for Duration` 1.16.0[src]

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

### `impl<T, U> Sum<Option<U>> for Option<T> where
T: Sum<U>,` 1.37.0[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>,` 1.16.0[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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