Module std::prelude

The Rust Prelude

Because std is required by most serious Rust software, it is imported at the topmost level of every crate by default, as if each crate contains the following:

extern crate std;

This means that the contents of std can be accessed from any context with the std:: path prefix, as in use std::vec, use std::thread::spawn, etc.

Additionally, std contains a versioned prelude that reexports many of the most common traits, types, and functions. The contents of the prelude are imported into every module by default. Implicitly, all modules behave as if they contained the following use statement:

use std::prelude::v1::*;

The prelude is primarily concerned with exporting traits that are so pervasive that they would be onerous to import for every use, particularly those that are commonly mentioned in generic type bounds.

The current version of the prelude (version 1) lives in std::prelude::v1, and reexports the following.

• std::marker::{ Copy, Send, Sized, Sync }. The marker traits indicate fundamental properties of types.
• std::ops::{ Drop, Fn, FnMut, FnOnce }. The destructor trait and the closure traits, reexported from the same module that also defines overloaded operators.
• std::mem::drop. A convenience function for explicitly dropping a value.
• std::boxed::Box. The owned heap pointer.
• std::borrow::ToOwned. The conversion trait that defines to_owned, the generic method for creating an owned type from a borrowed type.
• std::clone::Clone. The ubiquitous trait that defines clone, the method for producing copies of values that are consider expensive to copy.
• std::cmp::{ PartialEq, PartialOrd, Eq, Ord }. The comparision traits, which implement the comparison operators and are often seen in trait bounds.
• std::convert::{ AsRef, AsMut, Into, From }. Generic conversions, used by savvy API authors to create overloaded methods.
• std::default::Default. Types that have default values.
• std::iter::{ Iterator, Extend, IntoIterator, DoubleEndedIterator, ExactSizeIterator }. Iterators.
• std::option::Option::{ self, Some, None }. The ubiquitous Option type and its two variants, Some and None.
• std::result::Result::{ self, Ok, Err }. The ubiquitous Result type and its two variants, Ok and Err.
• std::slice::SliceConcatExt. An unstable extension to slices that shouldn't have to exist.
• std::string::{ String, ToString }. Heap allocated strings.
• std::vec::Vec. Heap allocated vectors.

Reexports

use core::prelude::v1::*;

Modules

v1	The first version of the prelude of The Rust Standard Library.