PyCon Otto 6-9 April 2017 Florence. Rusty Python. Rust, a new language for our programmer tool belt. Matteo

Transcription

1 PyCon Otto 6-9 April 2017 Florence Rusty Python Rust, a new language for our programmer tool belt Matteo 1

2 Rust Born as a personal project started in 2006 by Mozilla employee Graydon Hoare Mozilla began sponsoring the project in 2009 and announced it in 2010 A young language, with a growing usage in production (Dropbox, Mozilla, Canonical, OVH,...) 2. 1

3 2. 2

4 Hello, World! install the Rust toolchain with `rustup` $ cargo new hello-world --bin Created binary (application) `hello-world` project $ cd hello-world/ $ tree. Cargo.toml src main.rs 1 directory, 2 files 3

5 Hello, World! fn main() { println!("hello, World!"); huhu? `println!`? 4

6 How we run it? `cargo run` $ cargo run Compiling hello-world v0.1.0 (file:///home/naufraghi/.../hello-world) Finished dev [unoptimized + debuginfo] target(s) in 0.41 secs Running `target/debug/hello-world` Hello world! 5

7 Docstrings? //! Programma di esempio per _PyCon Otto_, //! l'immancabile «Hello, World!». fn main() { println!("hello, World!"); `cargo doc --open` 6

8 Integrated docs Cool, but in Python have `doctest`, I can't live without it! 7

9 And Rust "borrowed" the idea! //! Libreria di esempio per _PyCon Otto_, //! l'immancabile «Hello, World!». //! //! ``` //! use hello_world_lib::greater; //! let message = greater("world"); //! assert_eq!(message, "Hello, World!"); //! ``` pub fn greater(name: &str) -> String { format!("hello, {!", name) in fact a lot of ideas from Python 8

10 Run `cargo test --doc` $ cargo test --doc Finished dev [unoptimized + debuginfo] target(s) in 0.0 secs Doc-tests hello-world-lib running 1 test test greater_0... ok test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured 9

11 Let me see that code again... pub fn greater(name: &str) -> String { format!("hello, {!", name) Where is the `return`? It's implicit, the last expression is returned... beware of forgetting some `return` in Python after a switch :) 10

12 Optional arguments pub fn greater2(optional_name: Option<&str>) -> String { //! Restituisce un saluto di default se il nome è None //! //! ``` //! use hello_world_lib::greater2; //! let message = greater2(none); //! assert_eq!(message, "Hello, World!"); //! //! let message = greater2(some("matteo")); //! assert_eq!(message, "Hello, Matteo!"); //! ``` let name = match optional_name { Some(name) => name, None => "World", ; format!("hello, {!", name) no default values... yet `if` and `match`are expressions in Rust 11

13 Managing None Python var = some_optional_value() if var is not None: res = do_something_with(var) else: res = None Rust res = if let Some(var) = some_optional_value() { Some(do_something_with(var)) else { None 12

14 `None` is a serious thing fn main() { let out = if let Some(value) = some_optional_value("some") { do_something_with(value) else { None ; println!("out: {:?", out); 13

15 Nice error messages 14. 1

16 Rust Playground

17 In Rust we have other ways some_optional_value().map(do_something_with) pub enum Option<T> { None, Some(T), `Option::map` will not call `do_something_with` if the value is `None` 15

18 `Option` docs 16

19 Methods struct Circle { x: f64, y: f64, radius: f64, impl Circle { fn area(&self) -> f64 { std::f64::consts::pi * (self.radius * self.radius) self &self &mut self 17

20 Traits struct Circle { x: f64, y: f64, radius: f64, trait HasArea { fn area(&self) -> f64; this is what your lib users will need to implement impl HasArea for Circle { fn area(&self) -> f64 { std::f64::consts::pi * (self.radius * self.radius) 18

21 Duck typing Python def print_area(shape) { print("this shape has an area of {".format(shape.area())); Rust fn print_area<t: HasArea>(shape: T) { println!("this shape has an area of {", shape.area()); Traits are something we can use where in Python we were using duck typing 19

22 Implementing Traits class Counter(abc.Iterator): struct Counter { def init (self): count: usize, self.count = 0 def nxt (self): impl Counter { self.count += 1 fn new() -> Counter { return self.count Counter { count: 0 impl Iterator for Counter { type Item = usize; fn nxt(&mut self) -> Option<Self::Item> { self.count += 1; Some(self.count) with a typo in both Traits are somewhat similar to the `collections.abc` in Python 20

23 error[e0407]: method `nxt` is not a member of trait `Iterator` --> <anon>:11:5 Implementing Traits 11 fn nxt(&mut self) -> Option<Self::Item> { ^ starting here self.count += 1; >>> 13 c = Counter() Some(self.count) Traceback 14 (most recent call last): File ^ "<ipython-input-29-f3cf168481b9>",...ending here: not a member line of trait 1, in `Iterator` <module> c = Counter() TypeError: error[e0046]: Can't not instantiate all trait items abstract implemented, class Counter missing: with `next` abstract --> <anon>:9:1 methods next 9 impl Iterator for Counter { _^ starting here type Item = usize; 11 fn nxt(&mut self) -> Option<Self::Item> { 12 self.count += 1; 13 Some(self.count) _^...ending here: missing `next` in implementation = note: `next` from trait: `fn(&mut Self) -> std::option::option<<self as std::iter::iterator>::item>` Runtime check Compile time check 21

24 We have barely seen Rust as a language Rust is not easy, there are a lot of concepts, one can learn step-by-step. The tooling is good The docs are good Let's use Rust! 22

25 Let's rewrite Electric Sheep Fly down! Paper on 41 pages 23

26 Iterated Function System Barnsley fern Given 4 linear function with some magic parameters (a,b,c,d,e,f) / a b \ / x \ / e \ f(x,y) = + \ c d / \ y / \ f / Choose a random starting point, say (0,0) Loop: pick a random function apply the func on the last point collect the result 24

27 Iterated Function System F (x, y) w 1 1 F (x, y) w 2 2 F (x, y) w 3 3 F (x, y) w 4 4 p = F (p ) i+1 k i Plot the histogram Take one at random and collect the points 25. 1

28 Python for i in range(iterations): f = np.random.choice(arange(4), p=weights) if f == 0: P = F1 * P + F1c elif f == 1: P = F2 * P + F2c elif f == 2: P = F3 * P + F3c else: P = F4 * P + F4c if i > pointstoskip: drawpoints[frame][i-pointstoskip] = squeeze(asarray(p)) 25. 2

29 Rust for i in 0..iterations + 1 { let f = wc.ind_sample(&mut rng); if f == 1 { p = f1 * p + f1c; else if f == 2 { p = f2 * p + f2c; else if f == 3 { p = f3 * p + f3c; else { p = f4 * p + f4c; if i > points_to_skip { points.push((p.x, p.y)); 25. 3

30 How does it work? 26. 1

31 Build the extension $ python setup.py develop running develop running egg_info writing top-level names to ifs.egg-info/top_level.txt writing dependency_links to ifs.egg-info/dependency_links.txt writing ifs.egg-info/pkg-info reading manifest file 'ifs.egg-info/sources.txt' writing manifest file 'ifs.egg-info/sources.txt' running build_ext running build_rust cargo rustc --lib --manifest-path Cargo.toml \ --features cpython/extension-module cpython/python3-sys \ --release -- --crate-type cdylib Finished release [optimized] target(s) in 0.0 secs Creating /home/naufraghi/.../python3.5/site-packages/ifs.egg-link (link to.) ifs 1.0 is already the active version in easy-install.pth Installed /home/naufraghi/documents/src/rusty-python-pyconotto/barnsley-fern Processing dependencies for ifs==1.0 Finished processing dependencies for ifs==

32 Generating the fern $ python fern.py Using Python Frame 0 generated... Frame 11 generated Fern data generation completed in 23.3s Rendered frame Rendered frame 0011 Converting to animated gif... Gif Generated 26. 3

33 Generating the fern $ python fern.py rust Using Rust Frame 0 generated... Frame 11 generated Fern data generation completed in 0.4s Rendered frame Rendered frame 0011 Converting to animated gif... Gif Generated 26. 4

34 Generating the fern image size 300 -> 600 iterations > $ python fern.py rust Using Rust Frame 0 generated... Frame 11 generated Fern data generation completed in 3.3s Rendered frame Rendered frame 0011 Converting to animated gif... Gif Generated 26. 5

35 Python wrapper use cpython::{pyresult, Python; use barnsley_fern; py_module_initializer!(_iterated_function_systems, _inititerated_function_systems, PyInit iterated_function_systems, py, m { try!(m.add(py, " doc ", "Rust iterated function systems")); try!(m.add(py, "barnsley_fern", py_fn!(py, py_barnsley_fern(iterations: usize, points_to_skip: usize, bending: f64)))); Ok(()) ); fn py_barnsley_fern(py: Python, iterations: usize, points_to_skip: usize, bending: f64) -> PyResult<Vec<(f64, f64)>> { Ok(barnsley_fern(iterations, points_to_skip, bending)) 27

36 Python wrapper rust-cpython has an impl for most builtin types 28

37 from setuptools import setup from setuptools_rust import RustExtension setup.py setup(name='ifs', version='1.0', rust_extensions=[ RustExtension('ifs._iterated_function_systems', 'Cargo.toml', debug=false)], packages=['ifs'], # rust extensions are not zip safe, just like C-extensions. zip_safe=false) [package] name = "ifs" version = "0.1.0" authors = ["Matteo Bertini <matteo@naufraghi.net>"] [lib] name = "iterated_function_systems" crate-type = ["cdylib"] Cargo.toml [dependencies] nalgebra = "0.11.2" rand = "0.3.15" cpython = "0.1" 29

38 CI up and running matrix: allow_failures: os: osx include: - language: generic os: osx python: 2.7 env: [tox] envlist = py27, py35 [testenv] commands = - RUST_VERSION=stable - language: python python: 2.7 env: - RUST_VERSION=stabledeps =... pytest python setup.py install pip install example/ py.test # Manually install python on osx before_install: - if [[ $TRAVIS_OS_NAME == 'osx' ]]; then ci/osx-install.sh; fi install: - curl -ssf sh -s -- -y --default-toolchain $RUST_VERSION - export PATH="$HOME/.cargo/bin:$PATH" - rustc -V script: - sudo pip install tox - tox 30

39 Take away Rust seems to be here to stay Rust is high level enough Integrating Rust in Python is easy We can write fast and safe Rust extensions! 31

40 Thanks! Questions? 32. 1

41 Other choices Cython C: CPython / ffi c++: SIP (PyQt) c++: pybind11 (modern boost::python) fortran: f2py Rust: CPython / ffi 32. 2

42 Resources