Primitive Type unit1.0.0 [−]
The () type, sometimes called "unit" or "nil".
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 Default for ()[src]
impl PartialOrd<()> for ()[src]
fn partial_cmp(&self, &()) -> Option<Ordering>[src]
This method returns an ordering between self and other values if one exists. Read more
fn lt(&self, other: &Rhs) -> bool[src]
This method tests less than (for self and other) and is used by the < operator. Read more
fn le(&self, other: &Rhs) -> bool[src]
This method tests less than or equal to (for self and other) and is used by the <= operator. Read more
fn gt(&self, other: &Rhs) -> bool[src]
This method tests greater than (for self and other) and is used by the > operator. Read more
fn ge(&self, other: &Rhs) -> bool[src]
This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more
impl Eq for ()[src]
impl Hash for ()[src]
fn hash<H>(&self, _state: &mut H) where
H: Hasher, [src]
H: Hasher,
Feeds this value into the given [Hasher]. Read more
fn hash_slice<H>(data: &[Self], state: &mut H) where
H: Hasher, 1.3.0[src]
H: Hasher,
Feeds a slice of this type into the given [Hasher]. Read more
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
fn from_iter<I>(iter: I) where
I: IntoIterator<Item = ()>, [src]
I: IntoIterator<Item = ()>,
Creates a value from an iterator. Read more
impl Ord for ()[src]
fn cmp(&self, _other: &()) -> Ordering[src]
This method returns an Ordering between self and other. Read more
fn max(self, other: Self) -> Self1.21.0[src]
Compares and returns the maximum of two values. Read more
fn min(self, other: Self) -> Self1.21.0[src]
Compares and returns the minimum of two values. Read more
impl PartialEq<()> for ()[src]
fn eq(&self, _other: &()) -> bool[src]
This method tests for self and other values to be equal, and is used by ==. Read more
fn ne(&self, _other: &()) -> bool[src]
This method tests for !=.