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-rw-r--r--rust.html.markdown184
1 files changed, 113 insertions, 71 deletions
diff --git a/rust.html.markdown b/rust.html.markdown
index 0b9a5e58..d0c56b4a 100644
--- a/rust.html.markdown
+++ b/rust.html.markdown
@@ -5,11 +5,22 @@ contributors:
filename: learnrust.rs
---
-Rust is an in-development programming language developed by Mozilla Research.
-It is relatively unique among systems languages in that it can assert memory
-safety *at compile time*. Rust’s first alpha release occurred in January
-2012, and development moves so quickly that at the moment the use of stable
-releases is discouraged, and instead one should use nightly builds.
+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
@@ -24,7 +35,8 @@ Rust not only fast, but also easy and efficient to code in.
///////////////
// Functions
-fn add2(x: int, y: int) -> int {
+// `i32` is the type for 32-bit signed integers
+fn add2(x: i32, y: i32) -> i32 {
// Implicit return (no semicolon)
x + y
}
@@ -34,71 +46,90 @@ fn main() {
// Numbers //
// Immutable bindings
- let x: int = 1;
+ let x: i32 = 1;
// Integer/float suffixes
- let y: int = 13i;
+ let y: i32 = 13i32;
let f: f64 = 1.3f64;
// Type inference
- let implicit_x = 1i;
- let implicit_f = 1.3f64;
+ // 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;
- // Maths
- let sum = x + y + 13i;
+ // Arithmetic
+ let sum = x + y + 13;
// Mutable variable
let mut mutable = 1;
+ mutable = 4;
mutable += 2;
// Strings //
-
+
// String literals
- let x: &'static str = "hello world!";
+ let x: &str = "hello world!";
// Printing
println!("{} {}", f, x); // 1.3 hello world
- // A `String` - a heap-allocated string
+ // 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 characters of a string, just a pointer to
+ // 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.as_slice();
+ let s_slice: &str = &s;
println!("{} {}", s, s_slice); // hello world hello world
// Vectors/arrays //
// A fixed-size array
- let four_ints: [int, ..4] = [1, 2, 3, 4];
+ let four_ints: [i32; 4] = [1, 2, 3, 4];
- // A dynamically-sized vector
- let mut vector: Vec<int> = vec![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
+ // A slice – an immutable view into a vector or array
// This is much like a string slice, but for vectors
- let slice: &[int] = vector.as_slice();
+ 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);
- println!("{} {}", vector, slice); // [1, 2, 3, 4, 5] [1, 2, 3, 4, 5]
+ // 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: int,
- y: int,
+ x: i32,
+ y: i32,
}
let origin: Point = Point { x: 0, y: 0 };
- // Tuple struct
- struct Point2(int, int);
+ // A struct with unnamed fields, called a ‘tuple struct’
+ struct Point2(i32, i32);
let origin2 = Point2(0, 0);
@@ -110,16 +141,16 @@ fn main() {
Down,
}
- let up = Up;
+ let up = Direction::Up;
// Enum with fields
- enum OptionalInt {
- AnInt(int),
+ enum OptionalI32 {
+ AnI32(i32),
Nothing,
}
- let two: OptionalInt = AnInt(2);
- let nothing: OptionalInt = Nothing;
+ let two: OptionalI32 = OptionalI32::AnI32(2);
+ let nothing = OptionalI32::Nothing;
// Generics //
@@ -140,10 +171,10 @@ fn main() {
}
}
- let a_foo = Foo { bar: 1i };
+ let a_foo = Foo { bar: 1 };
println!("{}", a_foo.get_bar()); // 1
- // Traits (interfaces) //
+ // Traits (known as interfaces or typeclasses in other languages) //
trait Frobnicate<T> {
fn frobnicate(self) -> Option<T>;
@@ -155,30 +186,31 @@ fn main() {
}
}
- println!("{}", a_foo.frobnicate()); // Some(1)
+ let another_foo = Foo { bar: 1 };
+ println!("{:?}", another_foo.frobnicate()); // Some(1)
/////////////////////////
// 3. Pattern matching //
/////////////////////////
-
- let foo = AnInt(1);
+
+ let foo = OptionalI32::AnI32(1);
match foo {
- AnInt(n) => println!("it’s an int: {}", n),
- Nothing => println!("it’s nothing!"),
+ OptionalI32::AnI32(n) => println!("it’s an i32: {}", n),
+ OptionalI32::Nothing => println!("it’s nothing!"),
}
// Advanced pattern matching
- struct FooBar { x: int, y: OptionalInt }
- let bar = FooBar { x: 15, y: AnInt(32) };
+ struct FooBar { x: i32, y: OptionalI32 }
+ let bar = FooBar { x: 15, y: OptionalI32::AnI32(32) };
match bar {
- FooBar { x: 0, y: AnInt(0) } =>
+ FooBar { x: 0, y: OptionalI32::AnI32(0) } =>
println!("The numbers are zero!"),
- FooBar { x: n, y: AnInt(m) } if n == m =>
+ FooBar { x: n, y: OptionalI32::AnI32(m) } if n == m =>
println!("The numbers are the same"),
- FooBar { x: n, y: AnInt(m) } =>
+ FooBar { x: n, y: OptionalI32::AnI32(m) } =>
println!("Different numbers: {} {}", n, m),
- FooBar { x: _, y: Nothing } =>
+ FooBar { x: _, y: OptionalI32::Nothing } =>
println!("The second number is Nothing!"),
}
@@ -187,19 +219,20 @@ fn main() {
/////////////////////
// `for` loops/iteration
- let array = [1i, 2, 3];
+ let array = [1, 2, 3];
for i in array.iter() {
println!("{}", i);
}
- for i in range(0u, 10) {
+ // Ranges
+ for i in 0u32..10 {
print!("{} ", i);
}
println!("");
// prints `0 1 2 3 4 5 6 7 8 9 `
// `if`
- if 1i == 1 {
+ if 1 == 1 {
println!("Maths is working!");
} else {
println!("Oh no...");
@@ -213,7 +246,7 @@ fn main() {
};
// `while` loop
- while 1i == 1 {
+ while 1 == 1 {
println!("The universe is operating normally.");
}
@@ -225,40 +258,49 @@ fn main() {
/////////////////////////////////
// 5. Memory safety & pointers //
/////////////////////////////////
-
- // Owned pointer - only one thing can ‘own’ this pointer at a time
- let mut mine: Box<int> = box 3;
+
+ // 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 error
+ // println!("{}", mine); // this would not compile because `now_its_mine` now owns the pointer
- // Reference - an immutable pointer that refers to other data
- let mut var = 4i;
+ // 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: &int = &var;
+ let ref_var: &i32 = &var;
+
println!("{}", var); // Unlike `box`, `var` can still be used
println!("{}", *ref_var);
- // var = 5; // this would error
- // *ref_var = 6; // this would too
+ // 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
- let mut var2 = 4i;
- let ref_var2: &mut int = &mut var2;
- *ref_var2 += 2;
- println!("{}", *ref_var2); // 6
- // var2 = 2; // this would error
+ // 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 tutorial](http://doc.rust-lang.org/tutorial.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.
+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