Primitive Type unit1.0.0[−]
The () type, also called “unit”.
The () type has exactly one value (), and is used when there
is no other meaningful value that could be returned. () is most
commonly seen implicitly: functions without a -> ... implicitly
have return type (), that is, these are equivalent:
fn long() -> () {} fn short() {}Run
The semicolon ; can be used to discard the result of an
expression at the end of a block, making the expression (and thus
the block) evaluate to (). For example,
fn returns_i64() -> i64 { 1i64 } fn returns_unit() { 1i64; } let is_i64 = { returns_i64() }; let is_unit = { returns_i64(); };Run
Trait Implementations
impl Extend<()> for ()1.28.0[src]
impl Extend<()> for ()1.28.0[src]pub fn extend<T>(&mut self, iter: T) where
T: IntoIterator<Item = ()>, [src]
T: IntoIterator<Item = ()>,
pub fn extend_one(&mut self, _item: ())[src]
pub fn extend_reserve(&mut self, additional: usize)[src]
impl FromIterator<()> for ()1.23.0[src]
impl FromIterator<()> for ()1.23.0[src]Collapses all unit items from an iterator into one.
This is more useful when combined with higher-level abstractions, like
collecting to a Result<(), E> where you only care about errors:
use std::io::*; let data = vec![1, 2, 3, 4, 5]; let res: Result<()> = data.iter() .map(|x| writeln!(stdout(), "{}", x)) .collect(); assert!(res.is_ok());Run
pub fn from_iter<I>(iter: I) where
I: IntoIterator<Item = ()>, [src]
I: IntoIterator<Item = ()>,
impl PartialOrd<()> for ()[src]
impl PartialOrd<()> for ()[src]