Trait sp_std::iter::Sum

pub trait Sum<A = Self> {
    pub 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

pub 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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Implementations on Foreign Types

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

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

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

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

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

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

impl Sum<u8> for u8

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

impl Sum<usize> for usize

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

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

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

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

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

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

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

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

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

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

impl Sum<i64> for i64

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

impl Sum<i128> for i128

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

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

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

impl Sum<f64> for f64

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

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

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

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

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

impl Sum<u64> for u64

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

impl Sum<i8> for i8

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

impl Sum<u128> for u128

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

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

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

impl Sum<Duration> for Duration

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

impl Sum<u16> for u16

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

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

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

impl Sum<i16> for i16

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

impl Sum<u32> for u32

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

impl Sum<i32> for i32

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

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

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

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

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

impl Sum<f32> for f32

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

impl Sum<isize> for isize

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

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

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

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Implementors

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

pub 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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