1.12.0[−][src]Trait core::iter::Sum
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
Method which takes an iterator and generates Self
from the elements by
"summing up" the items.
Implementors
impl Sum<Wrapping<i128>> for Wrapping<i128>
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impl Sum<Wrapping<i16>> for Wrapping<i16>
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impl Sum<Wrapping<i32>> for Wrapping<i32>
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impl Sum<Wrapping<i64>> for Wrapping<i64>
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impl Sum<Wrapping<i8>> for Wrapping<i8>
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impl Sum<Wrapping<isize>> for Wrapping<isize>
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impl Sum<Wrapping<u128>> for Wrapping<u128>
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impl Sum<Wrapping<u16>> for Wrapping<u16>
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impl Sum<Wrapping<u32>> for Wrapping<u32>
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impl Sum<Wrapping<u64>> for Wrapping<u64>
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impl Sum<Wrapping<u8>> for Wrapping<u8>
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impl Sum<Wrapping<usize>> for Wrapping<usize>
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impl Sum<Duration> for Duration
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impl Sum<f32> for f32
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impl Sum<f64> for f64
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impl Sum<i128> for i128
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impl Sum<i16> for i16
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impl Sum<i32> for i32
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impl Sum<i64> for i64
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impl Sum<i8> for i8
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impl Sum<isize> for isize
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impl Sum<u128> for u128
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impl Sum<u16> for u16
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impl Sum<u32> for u32
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impl Sum<u64> for u64
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impl Sum<u8> for u8
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impl Sum<usize> for usize
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impl<'a> Sum<&'a Wrapping<i128>> for Wrapping<i128>
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impl<'a> Sum<&'a Wrapping<i16>> for Wrapping<i16>
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impl<'a> Sum<&'a Wrapping<i32>> for Wrapping<i32>
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impl<'a> Sum<&'a Wrapping<i64>> for Wrapping<i64>
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impl<'a> Sum<&'a Wrapping<i8>> for Wrapping<i8>
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impl<'a> Sum<&'a Wrapping<isize>> for Wrapping<isize>
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impl<'a> Sum<&'a Wrapping<u128>> for Wrapping<u128>
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impl<'a> Sum<&'a Wrapping<u16>> for Wrapping<u16>
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impl<'a> Sum<&'a Wrapping<u32>> for Wrapping<u32>
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impl<'a> Sum<&'a Wrapping<u64>> for Wrapping<u64>
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impl<'a> Sum<&'a Wrapping<u8>> for Wrapping<u8>
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impl<'a> Sum<&'a Wrapping<usize>> for Wrapping<usize>
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impl<'a> Sum<&'a Duration> for Duration
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impl<'a> Sum<&'a f32> for f32
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impl<'a> Sum<&'a f64> for f64
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impl<'a> Sum<&'a i128> for i128
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impl<'a> Sum<&'a i16> for i16
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impl<'a> Sum<&'a i32> for i32
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impl<'a> Sum<&'a i64> for i64
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impl<'a> Sum<&'a i8> for i8
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impl<'a> Sum<&'a isize> for isize
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impl<'a> Sum<&'a u128> for u128
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impl<'a> Sum<&'a u16> for u16
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impl<'a> Sum<&'a u32> for u32
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impl<'a> Sum<&'a u64> for u64
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impl<'a> Sum<&'a u8> for u8
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impl<'a> Sum<&'a usize> for usize
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impl<T, U> Sum<Option<U>> for Option<T> where
T: Sum<U>,
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T: Sum<U>,
fn sum<I>(iter: I) -> Option<T> where
I: Iterator<Item = Option<U>>,
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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));Run
impl<T, U, E> Sum<Result<U, E>> for Result<T, E> where
T: Sum<U>,
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T: Sum<U>,
fn sum<I>(iter: I) -> Result<T, E> where
I: Iterator<Item = Result<U, E>>,
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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));Run