1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134

//! # 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 first version of the prelude is used in Rust 2015 and Rust 2018,
//! and lives in [`std::prelude::v1`].
//! [`std::prelude::rust_2015`] and [`std::prelude::rust_2018`] re-export this prelude.
//! It re-exports the following:
//!
//! * <code>[std::marker]::{[Copy], [Send], [Sized], [Sync], [Unpin]}</code>,
//!   marker traits that indicate fundamental properties of types.
//! * <code>[std::ops]::{[Drop], [Fn], [FnMut], [FnOnce]}</code>, various
//!   operations for both destructors and overloading `()`.
//! * <code>[std::mem]::[drop][mem::drop]</code>, a convenience function for explicitly
//!   dropping a value.
//! * <code>[std::boxed]::[Box]</code>, a way to allocate values on the heap.
//! * <code>[std::borrow]::[ToOwned]</code>, the conversion trait that defines
//!   [`to_owned`], the generic method for creating an owned type from a
//!   borrowed type.
//! * <code>[std::clone]::[Clone]</code>, the ubiquitous trait that defines
//!   [`clone`][Clone::clone], the method for producing a copy of a value.
//! * <code>[std::cmp]::{[PartialEq], [PartialOrd], [Eq], [Ord]}</code>, the
//!   comparison traits, which implement the comparison operators and are often
//!   seen in trait bounds.
//! * <code>[std::convert]::{[AsRef], [AsMut], [Into], [From]}</code>, generic
//!   conversions, used by savvy API authors to create overloaded methods.
//! * <code>[std::default]::[Default]</code>, types that have default values.
//! * <code>[std::iter]::{[Iterator], [Extend], [IntoIterator], [DoubleEndedIterator], [ExactSizeIterator]}</code>,
//!   iterators of various
//!   kinds.
//! * <code>[std::option]::[Option]::{[self][Option], [Some], [None]}</code>, a
//!   type which expresses the presence or absence of a value. This type is so
//!   commonly used, its variants are also exported.
//! * <code>[std::result]::[Result]::{[self][Result], [Ok], [Err]}</code>, a type
//!   for functions that may succeed or fail. Like [`Option`], its variants are
//!   exported as well.
//! * <code>[std::string]::{[String], [ToString]}</code>, heap-allocated strings.
//! * <code>[std::vec]::[Vec]</code>, a growable, heap-allocated vector.
//!
//! The prelude used in Rust 2021, [`std::prelude::rust_2021`], includes all of the above,
//! and in addition re-exports:
//!
//! * <code>[std::convert]::{[TryFrom], [TryInto]}</code>,
//! * <code>[std::iter]::[FromIterator]</code>.
//!
//! [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::prelude::rust_2015`]: rust_2015
//! [`std::prelude::rust_2018`]: rust_2018
//! [`std::prelude::rust_2021`]: rust_2021
//! [std::result]: crate::result
//! [std::slice]: crate::slice
//! [std::string]: crate::string
//! [std::vec]: mod@crate::vec
//! [TryFrom]: crate::convert::TryFrom
//! [TryInto]: crate::convert::TryInto
//! [FromIterator]: crate::iter::FromIterator
//! [`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;

/// The 2015 version of the prelude of The Rust Standard Library.
///
/// See the [module-level documentation](self) for more.
#[stable(feature = "prelude_2015", since = "1.55.0")]
pub mod rust_2015 {
    #[stable(feature = "prelude_2015", since = "1.55.0")]
    #[doc(no_inline)]
    pub use super::v1::*;
}

/// The 2018 version of the prelude of The Rust Standard Library.
///
/// See the [module-level documentation](self) for more.
#[stable(feature = "prelude_2018", since = "1.55.0")]
pub mod rust_2018 {
    #[stable(feature = "prelude_2018", since = "1.55.0")]
    #[doc(no_inline)]
    pub use super::v1::*;
}

/// The 2021 version of the prelude of The Rust Standard Library.
///
/// See the [module-level documentation](self) for more.
#[stable(feature = "prelude_2021", since = "1.55.0")]
pub mod rust_2021 {
    #[stable(feature = "prelude_2021", since = "1.55.0")]
    #[doc(no_inline)]
    pub use super::v1::*;

    #[stable(feature = "prelude_2021", since = "1.55.0")]
    #[doc(no_inline)]
    pub use core::prelude::rust_2021::*;
}