Rust from Python & Ruby

Introduction to Rust for people that use Python and Ruby. Notice that this is about a work in progress Rust around version 0.4. YMMV.

Transcript

1. Rust
   from
   Python
   & Ruby
   

   View Slide

2. Armin Ronacher
   @mitsuhiko
   Python Dude
   (with Ruby experience)
   

   View Slide

3. What is Rust?
   

   View Slide

4. Programming
   Language
   printf("Hello "
   "World!\n");
   

   View Slide

5. UNDER CONSTRUCTION
   

   View Slide

6. def main():
   for name in ["Peter", "Paul", "Mary"]:
   print "Hello %s!" % name
   

   View Slide

7. def main
   ["Peter", "Paul", "Mary"].each do |name|
   puts "Hello %s!" % name
   end
   end
   

   View Slide

8. fn main() {
   for ["Peter", "Paul", "Mary"].each |name| {
   io::println(fmt!("Hello %s!", *name));
   }
   }
   

   View Slide

9. fn main() {
   let s = [1, 2, 3, 4].map(|x| (*x * *x).to_str());
   for s.each |item| {
   io::println(*item);
   }
   }
   

   View Slide

10. fn main() {
    let s = [1, 2, 3, 4].map(|&x| (x * x).to_str());
    for s.each |&item| {
    io::println(item);
    }
    }
    Soon TM
    

    View Slide

11. fn main() {
    let x = 42;
    let y = &x;
    let &z = y;
    io::println(fmt!("%d", z + z));
    }
    

    View Slide

12. $ cat hello.rs
    fn main() {
    io::println("Hello World!");
    }
    $ rustc -g hello.rs
    $ ./hello
    Hello World!
    Compile that
    

    View Slide

13. In a Nutshell
    

    View Slide

14. ✤ immutable by default
    ✤ static, algebraic, locally inferred types
    ✤ no dangling pointers, no overflows
    ✤ lightweight green tasks
    ✤ ahead-of-time compiled
    ✤ C compatible
    

    View Slide

15. -FUTMPPLDMPTFS
    

    View Slide

16. fn main() {
    for ["Peter", "Paul", "Mary"].each |name| {
    io::println(fmt!("Hello %s!", *name));
    }
    }
    

    View Slide

17. fn main() {
    ["Peter", "Paul", "Mary"].each(|name| {
    io::println(fmt!("Hello %s!", *name));
    true
    });
    }
    

    View Slide

18. Expressions
    

    View Slide

19. fn main() {
    let a = [1, 2, 3].map(|x| { *x; });
    let b = [1, 2, 3].map(|x| { *x });
    io::println(fmt!("a=%? b=%?", a, b));
    }
    /* a=~[ (), (), () ] b=~[ 1, 2, 3 ] */
    

    View Slide

20. Traits and
    Implementations
    

    View Slide

21. trait LengthPrintable {
    fn print_length();
    }
    

    View Slide

22. impl &[T]: LengthPrintable {
    fn print_length() {
    io::println(fmt!("length = %u", self.len()));
    }
    }
    

    View Slide

23. fn main() {
    ["Peter", "Paul", "Mary"].print_length();
    }
    

    View Slide

24. Memory Ownership
    

    View Slide

25. fn main() {
    let name = ~"Peter";
    let new_name = name;
    io::println(fmt!("Hello %s!", name));
    }
    Does not compile: string (currently) does not copy
    

    View Slide

26. fn main() {
    let name = ~"Peter";
    let new_name = move name;
    io::println(fmt!("Hello %s!", name));
    }
    Does not compile: using moved-out value
    

    View Slide

27. fn main() {
    let name = ~"Peter";
    let new_name = move name;
    io::println(fmt!("Hello %s!", new_name));
    }
    That compiles!
    

    View Slide

28. Not Null
    (algebraic data types)
    

    View Slide

29. def first_larger(seq, x):
    for item in seq:
    if item > x:
    return x
    Where is the NULL?
    

    View Slide

30. fn first_larger(seq: &[int], x: int) -> Option {
    for seq.each |item| {
    if *item > x { return Some(*item); }
    }
    None
    }
    

    View Slide

31. fn main() {
    let rv = first_larger([1, 2, 3, 4, 5], 3);
    io::println(match rv {
    Some(num) => fmt!("Found %d", num),
    None => ~"No number found"
    });
    }
    

    View Slide

32. Pattern Matching!
    

    View Slide

33. Enums
    (better than C's)
    

    View Slide

34. enum Shape {
    Point,
    Circle(float),
    Rect(float, float)
    }
    

    View Slide

35. impl Shape : ToStr {
    pure fn to_str() -> ~str {
    match self {
    Point => ~"point",
    Circle(r) => fmt!("circle of %f", r),
    Rect(w, h) => fmt!("rect of %f by %f", w, h)
    }
    }
    }
    

    View Slide

36. fn main() {
    let p = Point;
    let c = Circle(4.0f);
    io::println(fmt!("p=%s, c=%s",
    p.to_str(), c.to_str()));
    }
    

    View Slide

37. “Classes”
    

    View Slide

38. struct Point {
    mut x: float,
    mut y: float,
    }
    impl Point {
    static fn new(x: float, y: float) -> Point {
    Point { x: x, y: y }
    }
    }
    

    View Slide

39. impl Point : ToStr {
    pure fn to_str() -> ~str {
    fmt!("(%f, %f)", self.x, self.y)
    }
    }
    

    View Slide

40. fn main() {
    let p = Point::new(0.0f, 0.0f);
    io::println(p.to_str());
    }
    

    View Slide

41. Hold on a second!
    */)&3*5"/$& ?
    

    View Slide

42. trait inheritance
    no data inheritance !
    

    View Slide

43. Tasks
    

    View Slide

44. fn main() {
    for ["Peter", "Paul", "Mary"].each |name| {
    let name = *name;
    do task::spawn {
    let v = rand::Rng().shuffle([1, 2, 3]);
    for v.each |num| {
    io::print(fmt!("%s says: '%d'\n",
    name, *num));
    }
    }
    }
    }
    

    View Slide

45. FFI
    

    View Slide

46. #[link_args="-lcrypto"]
    extern {
    fn SHA1(s: *u8, l: libc::c_uint, d: *u8) -> *u8;
    }
    fn sha1(data: &str) -> ~str {
    unsafe {
    let bytes = str::to_bytes(data);
    let mut buf = [0u8, ..20];
    SHA1(vec::raw::to_ptr(bytes),
    bytes.len() as libc::c_uint,
    vec::raw::to_ptr(buf));
    as_hex(buf)
    }
    }
    

    View Slide

47. fn as_hex(data: &[u8]) -> ~str {
    let mut rv = ~"";
    for data.each |b| {
    rv += fmt!("%02x", *b as uint);
    }
    move rv
    }
    fn main() {
    io::println(sha1("Hello World!"));
    }
    

    View Slide

48. bindgen
    for the lazy:
    

    View Slide

49. Dear god …
    Why?
    

    View Slide

50. Why a new language?
    

    View Slide

51. Hello Concurrency
    

    View Slide

52. Why is concurrency
    messy?
    

    View Slide

53. Q: Why are global variables bad?
    A: there is only one of them!
    

    View Slide

54. Concurrency in web apps:
    What do you actually share?
    

    View Slide

55. Memory Tracking Enables
    Cheap Message Passing
    

    View Slide

56. Spaghetti Stacks
    

    View Slide

57. The Problems
    with Rust
    

    View Slide

58. strings not implicitly copyable
    

    View Slide

59. ownership tracking not perfect yet
    

    View Slide

60. generics are harder to implement
    

    View Slide

61. Option is a bit of a pain
    

    View Slide

62. directly using C APIs is icky
    

    View Slide

63. task scheduler oblivious of libuv
    

    View Slide

64. incomplete / work in progress
    

    View Slide

65. Q&A
    Thanks, now there is time for …
    @mitsuhiko
    http://lucumr.pocoo.org/
    http:// reteam.net/
    

    View Slide