Trait async_std::stream::Sum

pub trait Sum<A = Self>: Sized {
    fn sum<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'a>>
    where
        S: Stream<Item = A> + 'a;
}

This is supported on unstable only.

Trait to represent types that can be created by summing up a stream.

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

Required methods

fn sum<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'a>> where
    S: Stream<Item = A> + 'a, 

Method which takes a stream and generates Self from the elements by "summing up" the items.

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Implementations on Foreign Types

impl Sum<i8> for i8

fn sum<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'a>> where
    S: Stream<Item = i8> + 'a, 

This is supported on unstable only.

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

fn sum<'b, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'b>> where
    S: Stream<Item = &'a i8> + 'b, 

This is supported on unstable only.

impl Sum<i16> for i16

fn sum<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'a>> where
    S: Stream<Item = i16> + 'a, 

This is supported on unstable only.

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

fn sum<'b, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'b>> where
    S: Stream<Item = &'a i16> + 'b, 

This is supported on unstable only.

impl Sum<i32> for i32

fn sum<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'a>> where
    S: Stream<Item = i32> + 'a, 

This is supported on unstable only.

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

fn sum<'b, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'b>> where
    S: Stream<Item = &'a i32> + 'b, 

This is supported on unstable only.

impl Sum<i64> for i64

fn sum<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'a>> where
    S: Stream<Item = i64> + 'a, 

This is supported on unstable only.

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

fn sum<'b, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'b>> where
    S: Stream<Item = &'a i64> + 'b, 

This is supported on unstable only.

impl Sum<i128> for i128

fn sum<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'a>> where
    S: Stream<Item = i128> + 'a, 

This is supported on unstable only.

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

fn sum<'b, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'b>> where
    S: Stream<Item = &'a i128> + 'b, 

This is supported on unstable only.

impl Sum<isize> for isize

fn sum<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'a>> where
    S: Stream<Item = isize> + 'a, 

This is supported on unstable only.

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

fn sum<'b, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'b>> where
    S: Stream<Item = &'a isize> + 'b, 

This is supported on unstable only.

impl Sum<u8> for u8

fn sum<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'a>> where
    S: Stream<Item = u8> + 'a, 

This is supported on unstable only.

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

fn sum<'b, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'b>> where
    S: Stream<Item = &'a u8> + 'b, 

This is supported on unstable only.

impl Sum<u16> for u16

fn sum<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'a>> where
    S: Stream<Item = u16> + 'a, 

This is supported on unstable only.

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

fn sum<'b, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'b>> where
    S: Stream<Item = &'a u16> + 'b, 

This is supported on unstable only.

impl Sum<u32> for u32

fn sum<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'a>> where
    S: Stream<Item = u32> + 'a, 

This is supported on unstable only.

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

fn sum<'b, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'b>> where
    S: Stream<Item = &'a u32> + 'b, 

This is supported on unstable only.

impl Sum<u64> for u64

fn sum<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'a>> where
    S: Stream<Item = u64> + 'a, 

This is supported on unstable only.

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

fn sum<'b, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'b>> where
    S: Stream<Item = &'a u64> + 'b, 

This is supported on unstable only.

impl Sum<u128> for u128

fn sum<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'a>> where
    S: Stream<Item = u128> + 'a, 

This is supported on unstable only.

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

fn sum<'b, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'b>> where
    S: Stream<Item = &'a u128> + 'b, 

This is supported on unstable only.

impl Sum<usize> for usize

fn sum<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'a>> where
    S: Stream<Item = usize> + 'a, 

This is supported on unstable only.

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

fn sum<'b, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'b>> where
    S: Stream<Item = &'a usize> + 'b, 

This is supported on unstable only.

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

fn sum<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'a>> where
    S: Stream<Item = Wrapping<i8>> + 'a, 

This is supported on unstable only.

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

fn sum<'b, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'b>> where
    S: Stream<Item = &'a Wrapping<i8>> + 'b, 

This is supported on unstable only.

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

fn sum<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'a>> where
    S: Stream<Item = Wrapping<i16>> + 'a, 

This is supported on unstable only.

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

fn sum<'b, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'b>> where
    S: Stream<Item = &'a Wrapping<i16>> + 'b, 

This is supported on unstable only.

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

fn sum<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'a>> where
    S: Stream<Item = Wrapping<i32>> + 'a, 

This is supported on unstable only.

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

fn sum<'b, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'b>> where
    S: Stream<Item = &'a Wrapping<i32>> + 'b, 

This is supported on unstable only.

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

fn sum<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'a>> where
    S: Stream<Item = Wrapping<i64>> + 'a, 

This is supported on unstable only.

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

fn sum<'b, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'b>> where
    S: Stream<Item = &'a Wrapping<i64>> + 'b, 

This is supported on unstable only.

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

fn sum<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'a>> where
    S: Stream<Item = Wrapping<i128>> + 'a, 

This is supported on unstable only.

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

fn sum<'b, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'b>> where
    S: Stream<Item = &'a Wrapping<i128>> + 'b, 

This is supported on unstable only.

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

fn sum<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'a>> where
    S: Stream<Item = Wrapping<isize>> + 'a, 

This is supported on unstable only.

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

fn sum<'b, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'b>> where
    S: Stream<Item = &'a Wrapping<isize>> + 'b, 

This is supported on unstable only.

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

fn sum<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'a>> where
    S: Stream<Item = Wrapping<u8>> + 'a, 

This is supported on unstable only.

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

fn sum<'b, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'b>> where
    S: Stream<Item = &'a Wrapping<u8>> + 'b, 

This is supported on unstable only.

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

fn sum<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'a>> where
    S: Stream<Item = Wrapping<u16>> + 'a, 

This is supported on unstable only.

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

fn sum<'b, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'b>> where
    S: Stream<Item = &'a Wrapping<u16>> + 'b, 

This is supported on unstable only.

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

fn sum<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'a>> where
    S: Stream<Item = Wrapping<u32>> + 'a, 

This is supported on unstable only.

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

fn sum<'b, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'b>> where
    S: Stream<Item = &'a Wrapping<u32>> + 'b, 

This is supported on unstable only.

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

fn sum<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'a>> where
    S: Stream<Item = Wrapping<u64>> + 'a, 

This is supported on unstable only.

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

fn sum<'b, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'b>> where
    S: Stream<Item = &'a Wrapping<u64>> + 'b, 

This is supported on unstable only.

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

fn sum<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'a>> where
    S: Stream<Item = Wrapping<u128>> + 'a, 

This is supported on unstable only.

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

fn sum<'b, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'b>> where
    S: Stream<Item = &'a Wrapping<u128>> + 'b, 

This is supported on unstable only.

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

fn sum<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'a>> where
    S: Stream<Item = Wrapping<usize>> + 'a, 

This is supported on unstable only.

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

fn sum<'b, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'b>> where
    S: Stream<Item = &'a Wrapping<usize>> + 'b, 

This is supported on unstable only.

impl Sum<f32> for f32

fn sum<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'a>> where
    S: Stream<Item = f32> + 'a, 

This is supported on unstable only.

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

fn sum<'b, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'b>> where
    S: Stream<Item = &'a f32> + 'b, 

This is supported on unstable only.

impl Sum<f64> for f64

fn sum<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'a>> where
    S: Stream<Item = f64> + 'a, 

This is supported on unstable only.

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

fn sum<'b, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'b>> where
    S: Stream<Item = &'a f64> + 'b, 

This is supported on unstable only.

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

fn sum<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Result<T, E>> + 'a>> where
    S: Stream<Item = Result<U, E>> + 'a, 

This is supported on unstable only.

Takes each element in the Stream: 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:

use async_std::prelude::*;
use async_std::stream;

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

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

fn sum<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Option<T>> + 'a>> where
    S: Stream<Item = Option<U>> + 'a, 

This is supported on unstable only.

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:

use async_std::prelude::*;
use async_std::stream;

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

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Implementors

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