Primitive Type unit1.0.0[−]
Expand description
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() {}RunThe 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();
};RunTrait Implementations
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());RunCreates a value from an iterator. Read more
This method returns an ordering between self and other values if one exists. Read more
This method tests less than (for self and other) and is used by the < operator. Read more
This method tests less than or equal to (for self and other) and is used by the <=
operator. Read more
This method tests greater than (for self and other) and is used by the > operator. Read more