| //! The Rust Prelude. |
| //! |
| //! Rust comes with a variety of things in its standard library. However, if |
| //! you had to manually import every single thing that you used, it would be |
| //! very verbose. But importing a lot of things that a program never uses isn't |
| //! good either. A balance needs to be struck. |
| //! |
| //! The *prelude* is the list of things that Rust automatically imports into |
| //! every Rust program. It's kept as small as possible, and is focused on |
| //! things, particularly traits, which are used in almost every single Rust |
| //! program. |
| //! |
| //! On a technical level, Rust inserts |
| //! |
| //! ``` |
| //! # #[allow(unused_extern_crates)] |
| //! extern crate std; |
| //! ``` |
| //! |
| //! into the crate root of every crate, and |
| //! |
| //! ``` |
| //! # #[allow(unused_imports)] |
| //! use std::prelude::v1::*; |
| //! ``` |
| //! |
| //! into every module. |
| //! |
| //! # Other preludes |
| //! |
| //! Preludes can be seen as a pattern to make using multiple types more |
| //! convenient. As such, you'll find other preludes in the standard library, |
| //! such as [`std::io::prelude`]. Various libraries in the Rust ecosystem may |
| //! also define their own preludes. |
| //! |
| //! [`std::io::prelude`]: ../io/prelude/index.html |
| //! |
| //! The difference between 'the prelude' and these other preludes is that they |
| //! are not automatically `use`'d, and must be imported manually. This is still |
| //! easier than importing all of their constituent components. |
| //! |
| //! # Prelude contents |
| //! |
| //! The current version of the prelude (version 1) lives in |
| //! [`std::prelude::v1`], and re-exports the following. |
| //! |
| //! * [`std::marker`]::{[`Copy`], [`Send`], [`Sized`], [`Sync`], [`Unpin`]}. The |
| //! marker traits indicate fundamental properties of types. |
| //! * [`std::ops`]::{[`Drop`], [`Fn`], [`FnMut`], [`FnOnce`]}. Various |
| //! operations for both destructors and overloading `()`. |
| //! * [`std::mem`]::[`drop`][`mem::drop`], a convenience function for explicitly |
| //! dropping a value. |
| //! * [`std::boxed`]::[`Box`], a way to allocate values on the heap. |
| //! * [`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`][`Clone::clone`], the method for producing a copy of a value. |
| //! * [`std::cmp`]::{[`PartialEq`], [`PartialOrd`], [`Eq`], [`Ord`] }. The |
| //! comparison 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 of various |
| //! kinds. |
| //! * [`std::option`]::[`Option`]::{`self`, `Some`, `None`}. A type which |
| //! expresses the presence or absence of a value. This type is so commonly |
| //! used, its variants are also exported. |
| //! * [`std::result`]::[`Result`]::{`self`, `Ok`, `Err`}. A type for functions |
| //! that may succeed or fail. Like [`Option`], its variants are exported as |
| //! well. |
| //! * [`std::slice`]::[`SliceConcatExt`], a trait that exists for technical |
| //! reasons, but shouldn't have to exist. It provides a few useful methods on |
| //! slices. |
| //! * [`std::string`]::{[`String`], [`ToString`]}, heap allocated strings. |
| //! * [`std::vec`]::[`Vec`](../vec/struct.Vec.html), a growable, heap-allocated |
| //! vector. |
| //! |
| //! [`AsMut`]: ../convert/trait.AsMut.html |
| //! [`AsRef`]: ../convert/trait.AsRef.html |
| //! [`Box`]: ../boxed/struct.Box.html |
| //! [`Clone`]: ../clone/trait.Clone.html |
| //! [`Copy`]: ../marker/trait.Copy.html |
| //! [`Default`]: ../default/trait.Default.html |
| //! [`DoubleEndedIterator`]: ../iter/trait.DoubleEndedIterator.html |
| //! [`Drop`]: ../ops/trait.Drop.html |
| //! [`Eq`]: ../cmp/trait.Eq.html |
| //! [`ExactSizeIterator`]: ../iter/trait.ExactSizeIterator.html |
| //! [`Extend`]: ../iter/trait.Extend.html |
| //! [`FnMut`]: ../ops/trait.FnMut.html |
| //! [`FnOnce`]: ../ops/trait.FnOnce.html |
| //! [`Fn`]: ../ops/trait.Fn.html |
| //! [`From`]: ../convert/trait.From.html |
| //! [`IntoIterator`]: ../iter/trait.IntoIterator.html |
| //! [`Into`]: ../convert/trait.Into.html |
| //! [`Iterator`]: ../iter/trait.Iterator.html |
| //! [`Option`]: ../option/enum.Option.html |
| //! [`Ord`]: ../cmp/trait.Ord.html |
| //! [`PartialEq`]: ../cmp/trait.PartialEq.html |
| //! [`PartialOrd`]: ../cmp/trait.PartialOrd.html |
| //! [`Result`]: ../result/enum.Result.html |
| //! [`Send`]: ../marker/trait.Send.html |
| //! [`Sized`]: ../marker/trait.Sized.html |
| //! [`SliceConcatExt`]: ../slice/trait.SliceConcatExt.html |
| //! [`String`]: ../string/struct.String.html |
| //! [`Sync`]: ../marker/trait.Sync.html |
| //! [`ToOwned`]: ../borrow/trait.ToOwned.html |
| //! [`ToString`]: ../string/trait.ToString.html |
| //! [`Unpin`]: ../marker/trait.Unpin.html |
| //! [`Vec`]: ../vec/struct.Vec.html |
| //! [`Clone::clone`]: ../clone/trait.Clone.html#tymethod.clone |
| //! [`mem::drop`]: ../mem/fn.drop.html |
| //! [`std::borrow`]: ../borrow/index.html |
| //! [`std::boxed`]: ../boxed/index.html |
| //! [`std::clone`]: ../clone/index.html |
| //! [`std::cmp`]: ../cmp/index.html |
| //! [`std::convert`]: ../convert/index.html |
| //! [`std::default`]: ../default/index.html |
| //! [`std::iter`]: ../iter/index.html |
| //! [`std::marker`]: ../marker/index.html |
| //! [`std::mem`]: ../mem/index.html |
| //! [`std::ops`]: ../ops/index.html |
| //! [`std::option`]: ../option/index.html |
| //! [`std::prelude::v1`]: v1/index.html |
| //! [`std::result`]: ../result/index.html |
| //! [`std::slice`]: ../slice/index.html |
| //! [`std::string`]: ../string/index.html |
| //! [`std::vec`]: ../vec/index.html |
| //! [`to_owned`]: ../borrow/trait.ToOwned.html#tymethod.to_owned |
| //! [book-closures]: ../../book/first-edition/closures.html |
| //! [book-dtor]: ../../book/first-edition/drop.html |
| //! [book-enums]: ../../book/first-edition/enums.html |
| //! [book-iter]: ../../book/first-edition/iterators.html |
| |
| #![stable(feature = "rust1", since = "1.0.0")] |
| |
| pub mod v1; |
