mirror of
https://github.com/adambard/learnxinyminutes-docs.git
synced 2024-12-24 15:51:41 +03:00
308 lines
8.7 KiB
Markdown
308 lines
8.7 KiB
Markdown
---
|
||
language: rust
|
||
contributors:
|
||
- ["P1start", "http://p1start.github.io/"]
|
||
filename: learnrust.rs
|
||
---
|
||
|
||
Rust is a programming language developed by Mozilla Research.
|
||
Rust combines low-level control over performance with high-level convenience and
|
||
safety guarantees.
|
||
|
||
It achieves these goals without requiring a garbage collector or runtime, making
|
||
it possible to use Rust libraries as a "drop-in replacement" for C.
|
||
|
||
Rust’s first release, 0.1, occurred in January 2012, and for 3 years development
|
||
moved so quickly that until recently the use of stable releases was discouraged
|
||
and instead the general advice was to use nightly builds.
|
||
|
||
On May 15th 2015, Rust 1.0 was released with a complete guarantee of backward
|
||
compatibility. Improvements to compile times and other aspects of the compiler are
|
||
currently available in the nightly builds. Rust has adopted a train-based release
|
||
model with regular releases every six weeks. Rust 1.1 beta was made available at
|
||
the same time of the release of Rust 1.0.
|
||
|
||
Although Rust is a relatively low-level language, Rust has some functional
|
||
concepts that are generally found in higher-level languages. This makes
|
||
Rust not only fast, but also easy and efficient to code in.
|
||
|
||
```rust
|
||
// This is a comment. Single-line look like this...
|
||
/* ...and multi-line comment look like this */
|
||
|
||
///////////////
|
||
// 1. Basics //
|
||
///////////////
|
||
|
||
// Functions
|
||
// `i32` is the type for 32-bit signed integers
|
||
fn add2(x: i32, y: i32) -> i32 {
|
||
// Implicit return (no semicolon)
|
||
x + y
|
||
}
|
||
|
||
// Main function
|
||
fn main() {
|
||
// Numbers //
|
||
|
||
// Immutable bindings
|
||
let x: i32 = 1;
|
||
|
||
// Integer/float suffixes
|
||
let y: i32 = 13i32;
|
||
let f: f64 = 1.3f64;
|
||
|
||
// Type inference
|
||
// Most of the time, the Rust compiler can infer what type a variable is, so
|
||
// you don’t have to write an explicit type annotation.
|
||
// Throughout this tutorial, types are explicitly annotated in many places,
|
||
// but only for demonstrative purposes. Type inference can handle this for
|
||
// you most of the time.
|
||
let implicit_x = 1;
|
||
let implicit_f = 1.3;
|
||
|
||
// Arithmetic
|
||
let sum = x + y + 13;
|
||
|
||
// Mutable variable
|
||
let mut mutable = 1;
|
||
mutable = 4;
|
||
mutable += 2;
|
||
|
||
// Strings //
|
||
|
||
// String literals
|
||
let x: &str = "hello world!";
|
||
|
||
// Printing
|
||
println!("{} {}", f, x); // 1.3 hello world
|
||
|
||
// A `String` – a heap-allocated string
|
||
let s: String = "hello world".to_string();
|
||
|
||
// A string slice – an immutable view into another string
|
||
// This is basically an immutable pointer to a string – it doesn’t
|
||
// actually contain the contents of a string, just a pointer to
|
||
// something that does (in this case, `s`)
|
||
let s_slice: &str = &s;
|
||
|
||
println!("{} {}", s, s_slice); // hello world hello world
|
||
|
||
// Vectors/arrays //
|
||
|
||
// A fixed-size array
|
||
let four_ints: [i32; 4] = [1, 2, 3, 4];
|
||
|
||
// A dynamic array (vector)
|
||
let mut vector: Vec<i32> = vec![1, 2, 3, 4];
|
||
vector.push(5);
|
||
|
||
// A slice – an immutable view into a vector or array
|
||
// This is much like a string slice, but for vectors
|
||
let slice: &[i32] = &vector;
|
||
|
||
// Use `{:?}` to print something debug-style
|
||
println!("{:?} {:?}", vector, slice); // [1, 2, 3, 4, 5] [1, 2, 3, 4, 5]
|
||
|
||
// Tuples //
|
||
|
||
// A tuple is a fixed-size set of values of possibly different types
|
||
let x: (i32, &str, f64) = (1, "hello", 3.4);
|
||
|
||
// Destructuring `let`
|
||
let (a, b, c) = x;
|
||
println!("{} {} {}", a, b, c); // 1 hello 3.4
|
||
|
||
// Indexing
|
||
println!("{}", x.1); // hello
|
||
|
||
//////////////
|
||
// 2. Types //
|
||
//////////////
|
||
|
||
// Struct
|
||
struct Point {
|
||
x: i32,
|
||
y: i32,
|
||
}
|
||
|
||
let origin: Point = Point { x: 0, y: 0 };
|
||
|
||
// A struct with unnamed fields, called a ‘tuple struct’
|
||
struct Point2(i32, i32);
|
||
|
||
let origin2 = Point2(0, 0);
|
||
|
||
// Basic C-like enum
|
||
enum Direction {
|
||
Left,
|
||
Right,
|
||
Up,
|
||
Down,
|
||
}
|
||
|
||
let up = Direction::Up;
|
||
|
||
// Enum with fields
|
||
enum OptionalI32 {
|
||
AnI32(i32),
|
||
Nothing,
|
||
}
|
||
|
||
let two: OptionalI32 = OptionalI32::AnI32(2);
|
||
let nothing = OptionalI32::Nothing;
|
||
|
||
// Generics //
|
||
|
||
struct Foo<T> { bar: T }
|
||
|
||
// This is defined in the standard library as `Option`
|
||
enum Optional<T> {
|
||
SomeVal(T),
|
||
NoVal,
|
||
}
|
||
|
||
// Methods //
|
||
|
||
impl<T> Foo<T> {
|
||
// Methods take an explicit `self` parameter
|
||
fn get_bar(self) -> T {
|
||
self.bar
|
||
}
|
||
}
|
||
|
||
let a_foo = Foo { bar: 1 };
|
||
println!("{}", a_foo.get_bar()); // 1
|
||
|
||
// Traits (known as interfaces or typeclasses in other languages) //
|
||
|
||
trait Frobnicate<T> {
|
||
fn frobnicate(self) -> Option<T>;
|
||
}
|
||
|
||
impl<T> Frobnicate<T> for Foo<T> {
|
||
fn frobnicate(self) -> Option<T> {
|
||
Some(self.bar)
|
||
}
|
||
}
|
||
|
||
let another_foo = Foo { bar: 1 };
|
||
println!("{:?}", another_foo.frobnicate()); // Some(1)
|
||
|
||
/////////////////////////
|
||
// 3. Pattern matching //
|
||
/////////////////////////
|
||
|
||
let foo = OptionalI32::AnI32(1);
|
||
match foo {
|
||
OptionalI32::AnI32(n) => println!("it’s an i32: {}", n),
|
||
OptionalI32::Nothing => println!("it’s nothing!"),
|
||
}
|
||
|
||
// Advanced pattern matching
|
||
struct FooBar { x: i32, y: OptionalI32 }
|
||
let bar = FooBar { x: 15, y: OptionalI32::AnI32(32) };
|
||
|
||
match bar {
|
||
FooBar { x: 0, y: OptionalI32::AnI32(0) } =>
|
||
println!("The numbers are zero!"),
|
||
FooBar { x: n, y: OptionalI32::AnI32(m) } if n == m =>
|
||
println!("The numbers are the same"),
|
||
FooBar { x: n, y: OptionalI32::AnI32(m) } =>
|
||
println!("Different numbers: {} {}", n, m),
|
||
FooBar { x: _, y: OptionalI32::Nothing } =>
|
||
println!("The second number is Nothing!"),
|
||
}
|
||
|
||
/////////////////////
|
||
// 4. Control flow //
|
||
/////////////////////
|
||
|
||
// `for` loops/iteration
|
||
let array = [1, 2, 3];
|
||
for i in array.iter() {
|
||
println!("{}", i);
|
||
}
|
||
|
||
// Ranges
|
||
for i in 0u32..10 {
|
||
print!("{} ", i);
|
||
}
|
||
println!("");
|
||
// prints `0 1 2 3 4 5 6 7 8 9 `
|
||
|
||
// `if`
|
||
if 1 == 1 {
|
||
println!("Maths is working!");
|
||
} else {
|
||
println!("Oh no...");
|
||
}
|
||
|
||
// `if` as expression
|
||
let value = if true {
|
||
"good"
|
||
} else {
|
||
"bad"
|
||
};
|
||
|
||
// `while` loop
|
||
while 1 == 1 {
|
||
println!("The universe is operating normally.");
|
||
}
|
||
|
||
// Infinite loop
|
||
loop {
|
||
println!("Hello!");
|
||
}
|
||
|
||
/////////////////////////////////
|
||
// 5. Memory safety & pointers //
|
||
/////////////////////////////////
|
||
|
||
// Owned pointer – only one thing can ‘own’ this pointer at a time
|
||
// This means that when the `Box` leaves its scope, it can be automatically deallocated safely.
|
||
let mut mine: Box<i32> = Box::new(3);
|
||
*mine = 5; // dereference
|
||
// Here, `now_its_mine` takes ownership of `mine`. In other words, `mine` is moved.
|
||
let mut now_its_mine = mine;
|
||
*now_its_mine += 2;
|
||
|
||
println!("{}", now_its_mine); // 7
|
||
// println!("{}", mine); // this would not compile because `now_its_mine` now owns the pointer
|
||
|
||
// Reference – an immutable pointer that refers to other data
|
||
// When a reference is taken to a value, we say that the value has been ‘borrowed’.
|
||
// While a value is borrowed immutably, it cannot be mutated or moved.
|
||
// A borrow lasts until the end of the scope it was created in.
|
||
let mut var = 4;
|
||
var = 3;
|
||
let ref_var: &i32 = &var;
|
||
|
||
println!("{}", var); // Unlike `box`, `var` can still be used
|
||
println!("{}", *ref_var);
|
||
// var = 5; // this would not compile because `var` is borrowed
|
||
// *ref_var = 6; // this would not too, because `ref_var` is an immutable reference
|
||
|
||
// Mutable reference
|
||
// While a value is mutably borrowed, it cannot be accessed at all.
|
||
let mut var2 = 4;
|
||
let ref_var2: &mut i32 = &mut var2;
|
||
*ref_var2 += 2; // '*' is used to point to the mutably borrowed var2
|
||
|
||
println!("{}", *ref_var2); // 6 , //var2 would not compile. //ref_var2 is of type &mut i32, so //stores a reference to an i32 not the value.
|
||
// var2 = 2; // this would not compile because `var2` is borrowed
|
||
}
|
||
```
|
||
|
||
## Further reading
|
||
|
||
There’s a lot more to Rust—this is just the basics of Rust so you can understand
|
||
the most important things. To learn more about Rust, read [The Rust Programming
|
||
Language](http://doc.rust-lang.org/book/index.html) and check out the
|
||
[/r/rust](http://reddit.com/r/rust) subreddit. The folks on the #rust channel on
|
||
irc.mozilla.org are also always keen to help newcomers.
|
||
|
||
You can also try out features of Rust with an online compiler at the official
|
||
[Rust playpen](http://play.rust-lang.org) or on the main
|
||
[Rust website](http://rust-lang.org).
|