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diff --git a/rust.html.markdown b/rust.html.markdown index 3717a7d9..dcb54733 100644 --- a/rust.html.markdown +++ b/rust.html.markdown @@ -7,9 +7,13 @@ 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. +safety *at compile time* without resorting to garbage collection. Rust’s first +release, 0.1, 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. On January 9 2015, Rust 1.0 Alpha was released, and the rate of +changes to the Rust compiler that break existing code has dropped significantly +since. However, a complete guarantee of backward compatibility will not exist +until the final 1.0 release. 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 +28,8 @@ 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 +39,90 @@ 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 // - println!("{} {}", vector, slice); // [1, 2, 3, 4, 5] [1, 2, 3, 4, 5] + // 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: 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 +134,16 @@ 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 +164,10 @@ 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 +179,31 @@ 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 +212,20 @@ 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 +239,7 @@ fn main() { }; // `while` loop - while 1i == 1 { + while 1 == 1 { println!("The universe is operating normally."); } @@ -225,40 +251,49 @@ 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 too, because `ref_var` is an immutable reference // Mutable reference - let mut var2 = 4i; - let ref_var2: &mut int = &mut var2; + // 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; + println!("{}", *ref_var2); // 6 - // var2 = 2; // this would error + // 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 -Guide](http://doc.rust-lang.org/guide.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 |