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

fn sum<I>(iter: I) -> f32 where
    I: Iterator<Item = f32>, 

impl Sum<f64> for f64

fn sum<I>(iter: I) -> f64 where
    I: Iterator<Item = f64>, 

impl Sum<i128> for i128

fn sum<I>(iter: I) -> i128 where
    I: Iterator<Item = i128>, 

impl Sum<i16> for i16

fn sum<I>(iter: I) -> i16 where
    I: Iterator<Item = i16>, 

impl Sum<i32> for i32

fn sum<I>(iter: I) -> i32 where
    I: Iterator<Item = i32>, 

impl Sum<i64> for i64

fn sum<I>(iter: I) -> i64 where
    I: Iterator<Item = i64>, 

impl Sum<i8> for i8

fn sum<I>(iter: I) -> i8 where
    I: Iterator<Item = i8>, 

impl Sum<isize> for isize

fn sum<I>(iter: I) -> isize where
    I: Iterator<Item = isize>, 

impl Sum<u128> for u128

fn sum<I>(iter: I) -> u128 where
    I: Iterator<Item = u128>, 

impl Sum<u16> for u16

fn sum<I>(iter: I) -> u16 where
    I: Iterator<Item = u16>, 

impl Sum<u32> for u32

fn sum<I>(iter: I) -> u32 where
    I: Iterator<Item = u32>, 

impl Sum<u64> for u64

fn sum<I>(iter: I) -> u64 where
    I: Iterator<Item = u64>, 

impl Sum<u8> for u8

fn sum<I>(iter: I) -> u8 where
    I: Iterator<Item = u8>, 

impl Sum<usize> for usize

fn sum<I>(iter: I) -> usize where
    I: Iterator<Item = usize>, 

impl Sum<Wrapping<i128>> for Wrapping<i128>

fn sum<I>(iter: I) -> Wrapping<i128> where
    I: Iterator<Item = Wrapping<i128>>, 

impl Sum<Wrapping<i16>> for Wrapping<i16>

fn sum<I>(iter: I) -> Wrapping<i16> where
    I: Iterator<Item = Wrapping<i16>>, 

impl Sum<Wrapping<i32>> for Wrapping<i32>

fn sum<I>(iter: I) -> Wrapping<i32> where
    I: Iterator<Item = Wrapping<i32>>, 

impl Sum<Wrapping<i64>> for Wrapping<i64>

fn sum<I>(iter: I) -> Wrapping<i64> where
    I: Iterator<Item = Wrapping<i64>>, 

impl Sum<Wrapping<i8>> for Wrapping<i8>

fn sum<I>(iter: I) -> Wrapping<i8> where
    I: Iterator<Item = Wrapping<i8>>, 

impl Sum<Wrapping<isize>> for Wrapping<isize>

fn sum<I>(iter: I) -> Wrapping<isize> where
    I: Iterator<Item = Wrapping<isize>>, 

impl Sum<Wrapping<u128>> for Wrapping<u128>

fn sum<I>(iter: I) -> Wrapping<u128> where
    I: Iterator<Item = Wrapping<u128>>, 

impl Sum<Wrapping<u16>> for Wrapping<u16>

fn sum<I>(iter: I) -> Wrapping<u16> where
    I: Iterator<Item = Wrapping<u16>>, 

impl Sum<Wrapping<u32>> for Wrapping<u32>

fn sum<I>(iter: I) -> Wrapping<u32> where
    I: Iterator<Item = Wrapping<u32>>, 

impl Sum<Wrapping<u64>> for Wrapping<u64>

fn sum<I>(iter: I) -> Wrapping<u64> where
    I: Iterator<Item = Wrapping<u64>>, 

impl Sum<Wrapping<u8>> for Wrapping<u8>

fn sum<I>(iter: I) -> Wrapping<u8> where
    I: Iterator<Item = Wrapping<u8>>, 

impl Sum<Wrapping<usize>> for Wrapping<usize>

fn sum<I>(iter: I) -> Wrapping<usize> where
    I: Iterator<Item = Wrapping<usize>>, 

impl Sum<Duration> for Duration

fn sum<I>(iter: I) -> Duration where
    I: Iterator<Item = Duration>, 

impl<'a> Sum<&'a f32> for f32

fn sum<I>(iter: I) -> f32 where
    I: Iterator<Item = &'a f32>, 

impl<'a> Sum<&'a f64> for f64

fn sum<I>(iter: I) -> f64 where
    I: Iterator<Item = &'a f64>, 

impl<'a> Sum<&'a i128> for i128

fn sum<I>(iter: I) -> i128 where
    I: Iterator<Item = &'a i128>, 

impl<'a> Sum<&'a i16> for i16

fn sum<I>(iter: I) -> i16 where
    I: Iterator<Item = &'a i16>, 

impl<'a> Sum<&'a i32> for i32

fn sum<I>(iter: I) -> i32 where
    I: Iterator<Item = &'a i32>, 

impl<'a> Sum<&'a i64> for i64

fn sum<I>(iter: I) -> i64 where
    I: Iterator<Item = &'a i64>, 

impl<'a> Sum<&'a i8> for i8

fn sum<I>(iter: I) -> i8 where
    I: Iterator<Item = &'a i8>, 

impl<'a> Sum<&'a isize> for isize

fn sum<I>(iter: I) -> isize where
    I: Iterator<Item = &'a isize>, 

impl<'a> Sum<&'a u128> for u128

fn sum<I>(iter: I) -> u128 where
    I: Iterator<Item = &'a u128>, 

impl<'a> Sum<&'a u16> for u16

fn sum<I>(iter: I) -> u16 where
    I: Iterator<Item = &'a u16>, 

impl<'a> Sum<&'a u32> for u32

fn sum<I>(iter: I) -> u32 where
    I: Iterator<Item = &'a u32>, 

impl<'a> Sum<&'a u64> for u64

fn sum<I>(iter: I) -> u64 where
    I: Iterator<Item = &'a u64>, 

impl<'a> Sum<&'a u8> for u8

fn sum<I>(iter: I) -> u8 where
    I: Iterator<Item = &'a u8>, 

impl<'a> Sum<&'a usize> for usize

fn sum<I>(iter: I) -> usize where
    I: Iterator<Item = &'a usize>, 

impl<'a> Sum<&'a Wrapping<i128>> for Wrapping<i128>

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

impl<'a> Sum<&'a Wrapping<i16>> for Wrapping<i16>

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

impl<'a> Sum<&'a Wrapping<i32>> for Wrapping<i32>

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

impl<'a> Sum<&'a Wrapping<i64>> for Wrapping<i64>

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

impl<'a> Sum<&'a Wrapping<i8>> for Wrapping<i8>

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

impl<'a> Sum<&'a Wrapping<isize>> for Wrapping<isize>

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

impl<'a> Sum<&'a Wrapping<u128>> for Wrapping<u128>

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

impl<'a> Sum<&'a Wrapping<u16>> for Wrapping<u16>

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

impl<'a> Sum<&'a Wrapping<u32>> for Wrapping<u32>

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

impl<'a> Sum<&'a Wrapping<u64>> for Wrapping<u64>

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

impl<'a> Sum<&'a Wrapping<u8>> for Wrapping<u8>

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

impl<'a> Sum<&'a Wrapping<usize>> for Wrapping<usize>

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

impl<'a> Sum<&'a Duration> for Duration

fn sum<I>(iter: I) -> Duration where
    I: Iterator<Item = &'a Duration>, 

impl<T, U> Sum<Option<U>> for Option<T> where
    T: Sum<U>, 

fn sum<I>(iter: I) -> Option<T> where
    I: Iterator<Item = Option<U>>, 

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));

impl<T, U, E> Sum<Result<U, E>> for Result<T, E> where
    T: Sum<U>, 

fn sum<I>(iter: I) -> Result<T, E> where
    I: Iterator<Item = Result<U, E>>, 

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));

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