A functional view to Rust

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For attending Still here feel free to interrupt @flaper87 [email protected]

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What’s up with this Rust-lang thingy ?

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Does it really buy me something?

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What does it have to do with functional languages?

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Boring Stuff ~ and @ sigils are gone

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Boring Stuff ~ and @ sigils are gone Immutable by default

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Boring Stuff ~ and @ sigils are gone Immutable by default raii

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Boring Stuff ~ and @ sigils are gone Immutable by default raii almost everything is an expression

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Boring Stuff ~ and @ sigils are gone Immutable by default raii almost everything is an expression static with local inference

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Boring Stuff ~ and @ sigils are gone Immutable by default raii almost everything is an expression static with local inference linear Types

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Boring Stuff ~ and @ sigils are gone Immutable by default raii almost everything is an expression static with local inference linear Types ...

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Boring Stuff ~ and @ sigils are gone Immutable by default raii almost everything is an expression static with local inference linear Types ... ...

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Memory Safety

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passing by-ref “lends” the value fn main() { let mut x = 5; add_one(&mut x); println!("{}", x); } fn add_one(num: &mut i32) { *num += 1; }

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fn main() { let x = Box::new(5); add_one(x); println!("{}", x); // error } fn add_one(mut num: Box) { *num += 1; } passing by-val “gives” the value

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fn main() { let x = 5; add_one(x); println!("{}", x); // No error } fn add_one(num:i32) -> i32 { num + 1 } wait, you said no-ref moves the value

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Type & Trait system

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Bounded Polymorphism

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Bounds T: Send T: Sync T: Sync+Copy T: U

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struct MyType {...}

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struct MyType {...}

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fn send {...}

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Lifetimes

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struct Foo<'a> { x: &'a i32, } fn main() { let x; // -+ x goes into scope // | { // | let y = &5; // ---+ y goes into scope let f = Foo { x: y }; // ---+ f goes into scope x = &f.x; // | | error here } // ---+ f and y go out of scope // | println!("{}", x); // | } lifetimes, regions, scope…

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Mutability

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Is mutability limited to linearity? fn main() { let mut x = 5; add_one(&mut x); println!("{}", x); } fn add_one(num: &mut i32) { *num += 1; }

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Inherited Mutability fn main() { let x = MyStruct {a: 5}; let mut z = x; // z.a is mutable println!("{}", x); }

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Internal Mutability fn main() { let x = Cell(5); x.set(6); }

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Soundness

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struct Foo<'a> { x: &'a mut i32, // ERROR: &mut T is not copyable } impl<’a> Copy for Foo {} fn is_copy() {} fn main() { is_copy::(); } unaliased mutable references

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struct Foo<'a> { x: &'a i32, } impl<’a> Copy for Foo {} fn is_copy() {} fn main() { is_copy::(); }

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Enough with the type system

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Pattern Matching

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Pattern Matching enum OptInt { Value(i32), Missing, // Warning on unused variant } match OptInt::Value(5) { OptInt::Value(a) if a > 5 => println!("{}", a), OptInt::Value(a) => println!("Got an int: {}!", a), OptInt::Missing => println!("No such luck."), }

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Pattern Matching let x = 5; match x { i @ 1 … 5 => println!("got range item: {}!", i), _ => println!("anything!") }

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Iterators

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Iterator trait: fold let sum = (1..4).fold(0, |sum, x| sum + x);

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Iterator trait: filter for i in (1..100).filter(|&x| x % 2 == 0) { println!("{}", i); }

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Iterator trait: map for i in (1..100).map(|x| x + 1) { println!("{}", i); }

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Thread, Mutex, Channel

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Channels use std::sync::{Arc, Mutex}; use std::thread; use std::sync::mpsc; fn main() { let data = Arc::new(Mutex::new(0u32)); let (tx, rx) = mpsc::channel(); for _ in 0..10 { let (data, tx) = (data.clone(), tx.clone()); thread::spawn(move || { let mut data = data.lock().unwrap(); *data += 1; tx.send(()); }); } for _ in 0..10 { rx.recv(); } } Multi-producer Single-consumer

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Questions?