mod.rs - source
Description: Source of the Rust file `library/std/src/prelude/mod.rs`.
Keywords: rust, rustlang, rust-lang

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    //! 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.
    //!
    //! # 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`]: crate::io::prelude
    //!
    //! 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`][`Option`], [`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`][`Result`], [`Ok`], [`Err`]}. A type
    //!   for functions that may succeed or fail. Like [`Option`], its variants are
    //!   exported as well.
    //! * [`std::string`]::{[`String`], [`ToString`]}, heap allocated strings.
    //! * [`std::vec`]::[`Vec`], a growable, heap-allocated
    //!   vector.
    //!
    //! [`mem::drop`]: crate::mem::drop
    //! [`std::borrow`]: crate::borrow
    //! [`std::boxed`]: crate::boxed
    //! [`std::clone`]: crate::clone
    //! [`std::cmp`]: crate::cmp
    //! [`std::convert`]: crate::convert
    //! [`std::default`]: crate::default
    //! [`std::iter`]: crate::iter
    //! [`std::marker`]: crate::marker
    //! [`std::mem`]: crate::mem
    //! [`std::ops`]: crate::ops
    //! [`std::option`]: crate::option
    //! [`std::prelude::v1`]: v1
    //! [`std::result`]: crate::result
    //! [`std::slice`]: crate::slice
    //! [`std::string`]: crate::string
    //! [`std::vec`]: mod@crate::vec
    //! [`to_owned`]: crate::borrow::ToOwned::to_owned
    //! [book-closures]: ../../book/ch13-01-closures.html
    //! [book-dtor]: ../../book/ch15-03-drop.html
    //! [book-enums]: ../../book/ch06-01-defining-an-enum.html
    //! [book-iter]: ../../book/ch13-02-iterators.html

    #![stable(feature = "rust1", since = "1.0.0")]

    pub mod v1;