diff options
| -rw-r--r-- | library/core/src/iter/traits/accum.rs | 40 | ||||
| -rw-r--r-- | library/core/src/iter/traits/iterator.rs | 6 |
2 files changed, 42 insertions, 4 deletions
diff --git a/library/core/src/iter/traits/accum.rs b/library/core/src/iter/traits/accum.rs index e31669b3924..f9c7eb8f938 100644 --- a/library/core/src/iter/traits/accum.rs +++ b/library/core/src/iter/traits/accum.rs @@ -164,12 +164,13 @@ where /// element is encountered: /// /// ``` + /// let f = |&x: &i32| if x < 0 { Err("Negative element found") } else { Ok(x) }; /// 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(); + /// let res: Result<i32, _> = v.iter().map(f).sum(); /// assert_eq!(res, Ok(3)); + /// let v = vec![1, -2]; + /// let res: Result<i32, _> = v.iter().map(f).sum(); + /// assert_eq!(res, Err("Negative element found")); /// ``` fn sum<I>(iter: I) -> Result<T, E> where @@ -187,6 +188,20 @@ where /// 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 product of all elements is returned. + /// + /// # Examples + /// + /// This multiplies each number in a vector of strings, + /// if a string could not be parsed the operation returns `Err`: + /// + /// ``` + /// let nums = vec!["5", "10", "1", "2"]; + /// let total: Result<usize, _> = nums.iter().map(|w| w.parse::<usize>()).product(); + /// assert_eq!(total, Ok(100)); + /// let nums = vec!["5", "10", "one", "2"]; + /// let total: Result<usize, _> = nums.iter().map(|w| w.parse::<usize>()).product(); + /// assert!(total.is_err()); + /// ``` fn product<I>(iter: I) -> Result<T, E> where I: Iterator<Item = Result<U, E>>, @@ -213,6 +228,9 @@ where /// let words = vec!["have", "a", "great", "day"]; /// let total: Option<usize> = words.iter().map(|w| w.find('a')).sum(); /// assert_eq!(total, Some(5)); + /// let words = vec!["have", "a", "good", "day"]; + /// let total: Option<usize> = words.iter().map(|w| w.find('a')).sum(); + /// assert_eq!(total, None); /// ``` fn sum<I>(iter: I) -> Option<T> where @@ -230,6 +248,20 @@ where /// 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 product of all elements is returned. + /// + /// # Examples + /// + /// This multiplies each number in a vector of strings, + /// if a string could not be parsed the operation returns `None`: + /// + /// ``` + /// let nums = vec!["5", "10", "1", "2"]; + /// let total: Option<usize> = nums.iter().map(|w| w.parse::<usize>().ok()).product(); + /// assert_eq!(total, Some(100)); + /// let nums = vec!["5", "10", "one", "2"]; + /// let total: Option<usize> = nums.iter().map(|w| w.parse::<usize>().ok()).product(); + /// assert_eq!(total, None); + /// ``` fn product<I>(iter: I) -> Option<T> where I: Iterator<Item = Option<U>>, diff --git a/library/core/src/iter/traits/iterator.rs b/library/core/src/iter/traits/iterator.rs index 6c3030336c6..16c9f668b8e 100644 --- a/library/core/src/iter/traits/iterator.rs +++ b/library/core/src/iter/traits/iterator.rs @@ -3448,6 +3448,9 @@ pub trait Iterator { /// /// An empty iterator returns the zero value of the type. /// + /// `sum()` can be used to sum any type implementing [`Sum`][`core::iter::Sum`], + /// including [`Option`][`Option::sum`] and [`Result`][`Result::sum`]. + /// /// # Panics /// /// When calling `sum()` and a primitive integer type is being returned, this @@ -3478,6 +3481,9 @@ pub trait Iterator { /// /// An empty iterator returns the one value of the type. /// + /// `product()` can be used to multiply any type implementing [`Product`][`core::iter::Product`], + /// including [`Option`][`Option::product`] and [`Result`][`Result::product`]. + /// /// # Panics /// /// When calling `product()` and a primitive integer type is being returned, |