Deep drive into rust programming language

Introduction to Rust
@dvigneshwer

Viki::About();
- Lives in Bengaluru, India
- Works at MuSigma Research
- Mozilla Representative in India
- Developing DeepRust Crate
- Author of Rust CookBook by Packt
- Mozilla TechSpeaker Program member

Agenda
1. Basic Terminologies
2. Common System programming bugs
3. Why Rust?
4. Intro to Rust
5. Type System
6. Ownership and Borrowing
7. Getting started with Rust community
8. ???

Basic Terminologies
● Low and high level language
● System programming
● Stack and heap
● Concurrency and parallelism
● Compile time and run time
● Type system
● Garbage collector
● Mutability
● Scope

Common System Programming Errors
● Segmentation Fault
● Buffer OverFlow

Segmentation Fault
● Dereference a null pointer
● Try to write to a portion of memory that was marked as read-only

Buffer OverFlow
● Writing and reading the past end of buffer

Sample Error Outputs
● Segmentation fault
● BufferOverFlow

Why do we need a new system programming
language?
● State or art programming language
● Solves a lot of common system programming bugs
● Cargo : Rust Package manager
● Improving your toolkit
● Self learning
● It's FUN ...

Rust
● System programming language
● Has great control like C/C++
● Safety and expressive like python

Best things about Rust
● Strong type system
○ Reduces a lot of common bugs
● Borrowing and Ownership
○ Memory safety
○ Freedom from data races
● Zero Cost abstraction

Installing Rust
# Ubuntu / MacOS
● Open your terminal (cntrl + Alt +T)
● curl -sSf https://static.rust-lang.org/rustup.sh | sh

Installing Rust
rustc --version
cargo --version
# Windows
● Go to https://win.rustup.rs/
○ This will download rustup-init.exe
● Double click and start the installation

Hello World
fn main() {
let greet = “world”;
println!("Hello {}!”, greet);
}

A bit complex example
fn avg(list: &[f64]) -> f64 {
let mut total = 0;
for el in list{
total += *el
}
total/list.len() as f64
}

HLL version
fn avg(list: &[f64]) -> f64 {
list.iter().sum::<f64>() / list.len() as f64
}

Parallel Version (Rayon)
fn avg(list: &[f64]) -> f64 {
list.par_iter().sum::<f64>() / list.len() as f64
}

Fold
fn avg(list: &[f64]) -> f64 {
list.par_iter().fold(0., |a,b| a + b) / list.len() as f64
}

bool
let bool_val: bool = true;
println!("Bool value is {}", bool_val);

char
let x_char: char = 'a';
// Printing the character
println!("x char is {}", x_char);

i8/i16/i32/i64/isize
let num =10;
println!("Num is {}", num);
let age: i32 =40;
println!("Age is {}", age);
println!("Max i32 {}",i32::MAX);
println!("Max i32 {}",i32::MIN);

Other Primitive Types
● u8/u16/u32/u64/usize
● f32/f64

Tuples
// Declaring a tuple
let rand_tuple = ("Mozilla Science Lab", 2016);
let rand_tuple2 : (&str, i8) = ("Viki",4);
// tuple operations
println!(" Name : {}", rand_tuple2.0);
println!(" Lucky no : {}", rand_tuple2.1);

Arrays
let rand_array = [1,2,3]; // Defining an array
println!("random array {:?}",rand_array );
println!("random array 1st element {}",rand_array[0] ); // indexing starts with 0
println!("random array length {}",rand_array.len() );
println!("random array {:?}",&rand_array[1..3] ); // last two elements

String
let rand_string = "I love Mozilla Science <3"; // declaring a random string
println!("length of the string is {}",rand_string.len() ); // printing the length of the
string
let (first,second) = rand_string.split_at(7); // Splits in string
let count = rand_string.chars().count(); // Count using iterator count

struct
// define your custom user datatype
struct Circle {
x : f64,
radius : f64,
}

Rust “Class”
impl Circle {
// pub makes this function public which makes it accessible outsite the scope {}
pub fn get_x(&self) -> f64 {
self.x
}
}

Traits
● Interfaces
● Operator overloading
● Indicators of behaviour
● Bounds for generic
● Dynamic dispatch

Trait Sample
// create a functionality for the datatypes
trait HasArea {
fn area(&self) -> f64;
}
// implement area for circle
impl HasArea for Circle {
fn area(&self) -> f64 {
3.14 * (self.r *self.r)
}
}

Ownership
In Rust, every value has an “owning scope,” and passing or returning a value
means transferring ownership (“moving” it) to a new scope

Example 1
fn foo{
let v = vec![1,2,3];
let x = v;
println!(“{:?}”,v); // ERROR : use of moved value: “v”
}

fn print(v : Vec<u32>) {
println!(“{:?}”, v);
}
fn make_vec() {
let v = vec![1,2,3];
print(v);
print(v); // ERROR : use of moved value: “v”
}

Ownership
Step 1.
Step 2. Step 3.

Aliasing
More than one pointer to the same memory
Ownership concepts avoids Aliasing

Borrowing
If you have access to a value in Rust, you can lend out that access to the
functions you call

Types of Borrowing
There is two type of borrowing in Rust, both the cases aliasing and mutation do
not happen simultaneously
● Shared Borrowing (&T)
● Mutable Borrow (&mut T)

&mut T
fn add_one(v: &mut Vec<u32> ) {
v.push(1)
}
fn foo() {
let mut v = Vec![1,2,3];
add_one(&mut v);
}

Rules of Borrowing
● Mutable borrows are exclusive
● Cannot outlive the object being borrowed

Cannot outlive the object being borrowed
fn foo{
let mut v = vec![1,2,3];
let borrow1 = &v;
let borrow2 = &v;
add_one(&mut v): // ERROR : cannot borrow ‘v’ as mutuable because
} it is also borrowed as immutable

Lifetimes
let outer;
{
let v = 1;
outer = &v; // ERROR: ‘v’ doesn’t live long
}
println!(“{}”, outer);

Getting started with Rust community
● Follow all the latest news at Reddit Channel
○ https://www.reddit.com/r/rust/
● Have doubts, post in
○ https://users.rust-lang.org
○ #rust IRC channel
● Want to publish a crate,
○ https://crates.io
● Follow @rustlang in twitter,
○ https://twitter.com/rustlang
● Subscribe to https://this-week-in-rust.org/ newsletter

Getting started with Rust community
● Create your rustaceans profile,
○ Fork https://github.com/nrc/rustaceans.org
○ Create a file in data directory with <github_id>.json
■ Ex: dvigneshwer.json

References
● Segfault:
http://stackoverflow.com/questions/2346806/what-is-a-segmentation-fault
● BufferOverFlow:
http://stackoverflow.com/questions/574159/what-is-a-buffer-overflow-and-how
-do-i-cause-one
● Rust Website: https://www.rust-lang.org/en-US/
● Community Forum: https://users.rust-lang.org/
● Rust Book: https://doc.rust-lang.org/book/
● Unraveling Rust Design:
https://dvigneshwer.wordpress.com/2017/02/25/unraveling-rust-design/
● Rust Cookbook:
https://www.packtpub.com/application-development/rust-cookbook

Contribute
● https://github.com/MozillaTN/Rust
● https://github.com/dvigneshwer/deeprust
● https://github.com/dvigneshwer/Benchmarking_Rust
● https://github.com/servo

Thank You
● Tweet at #RustIndia
● Join RustIndia Telegram group

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