feat(arrived at types)

.gitignore

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+/target

Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "rust-by-example"
+version = "0.1.0"

Cargo.toml

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+[package]
+name = "rust-by-example"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]

src/customtypes.rs

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+#![allow(dead_code)]
+
+pub fn custom_types_module() {
+    // struct
+    // 1. Tuple structs, basically named tuples
+    struct Pair(i32, i32);
+    let pair = Pair(1, 2);
+    let Pair(_int1, _int2) = pair; // tuple structs can be destructured
+
+    // 2. C structs
+    struct Point {
+        x: f32,
+        y: f32,
+    }
+
+    struct Polygon<'a, T> {
+        points: [Point; 1],
+        sliced_points: &'a [T],
+    }
+
+    let point_top: Point = Point { x: 1.0, y: 1.0 };
+    let point_list: [Point; 2] = [Point { x: 2.0, y: 3.0 }, Point { x: 3.0, y: 4.0 }];
+
+    let _point_borrow: Point = Point {
+        x: 6.0,
+        ..point_top
+    };
+
+    let _my_triangle = Polygon {
+        points: [point_top],
+        sliced_points: &point_list,
+    };
+
+    // 3. Unit structs, field-less, useful for generics
+    // 0 bytes of size, useful as markers and indicate variants
+    struct Unit;
+    let _unit = Unit;
+
+    /*
+    impl Something for Unit {
+        ...
+    }
+    */
+
+    // EXERCISE 1: create a triangle struct and a rect_area function, use nested destruturing
+    #[derive(Debug, Clone)] // to allow printing, and cloning, last one with a performace loss
+    struct MyPoint {
+        x: f32,
+        y: f32,
+    }
+
+    fn distance(a: MyPoint, b: MyPoint) -> f32 {
+        return ((b.x - a.x).powf(2.0) + (b.y - a.y).powf(2.0)).sqrt();
+    }
+
+    struct Rectangle {
+        corners: [MyPoint; 4],
+    }
+
+    fn rect_area(rect: Rectangle) -> f32 {
+        let Rectangle { corners } = rect;
+
+        for i in 0..corners.len() {
+            println!("Corner {}: {:?}", i, corners[i])
+        }
+
+        return distance(corners[0].clone(), corners[1].clone())
+            * distance(corners[0].clone(), corners[2].clone());
+    }
+
+    let my_rectangle = Rectangle {
+        corners: [
+            MyPoint { x: 0.0, y: 0.0 },
+            MyPoint { x: 4.0, y: 0.0 },
+            MyPoint { x: 0.0, y: 4.0 },
+            MyPoint { x: 4.0, y: 4.0 },
+        ],
+    };
+
+    let my_rectangle_area = rect_area(my_rectangle);
+    println!("My rectangle area: {}", my_rectangle_area);
+
+    // EXERCISE 2: create a function that returns a square out of a point
+    fn square(p: MyPoint, size: f32) -> Rectangle {
+        return Rectangle {
+            corners: [
+                MyPoint { x: p.x, y: p.y }, // don't know yet how to use borrowing properly
+                MyPoint {
+                    x: p.x + size,
+                    y: p.y,
+                },
+                MyPoint {
+                    x: p.x,
+                    y: p.y + size,
+                },
+                MyPoint {
+                    x: p.x + size,
+                    y: p.y + size,
+                },
+            ],
+        };
+    }
+
+    let my_square = square(MyPoint { x: 0.0, y: 0.0 }, 2.0);
+
+    println!("My square: ");
+    for i in 0..my_square.corners.len() {
+        match my_square.corners.get(i) {
+            Some(xval) => print!("{:?}", xval),
+            None => println!("You went too far"),
+        }
+    }
+
+    // enum
+    // ill make literally the example on rust-by-example
+    enum WebEvent {
+        PageLoad,
+        PageUnload,
+        Click { x: i64, y: i64 },
+    }
+
+    fn inspect_web_event(event: WebEvent) {
+        match event {
+            // switch over the enum
+            WebEvent::PageLoad => println!("Page loaded"),
+            WebEvent::PageUnload => println!("Page unload"),
+            WebEvent::Click { x, y } => println!("clicked at {}, {}", x, y),
+        }
+    }
+
+    let load = WebEvent::PageLoad;
+    let unload = WebEvent::PageUnload;
+    let click = WebEvent::Click { x: 20, y: 0 };
+
+    inspect_web_event(load);
+    inspect_web_event(unload);
+    inspect_web_event(click);
+
+    // enums can be used over a type alias
+    type MyEventType = WebEvent;
+
+    let another_click = MyEventType::Click { x: 0, y: 20 };
+    inspect_web_event(another_click);
+
+    // can also use "use crate::" to avoid manual scoping
+    use WebEvent::{Click, PageUnload};
+
+    let yet_another_click = Click { x: 10, y: 0 };
+    let another_unload = PageUnload;
+    inspect_web_event(yet_another_click);
+    inspect_web_event(another_unload);
+
+    // c-like enums
+    enum Number {
+        // implicit start at 0
+        Zero,
+        One,
+        Two,
+    }
+    enum Color {
+        Red = 0xff0000,
+        Green = 0x00ff00,
+        Blue = 0x0000ff,
+    }
+
+    println!("zero is {}", Number::Zero as i32);
+    println!("one is {}", Number::One as i32);
+
+    println!("roses are #{:06x}", Color::Red as i32);
+    println!("violets are #{:06x}", Color::Blue as i32);
+
+    // Linked list implemented with enums
+
+    enum List {
+        Cons(u32, Box<List>), // tuple struct with an element (u32) and a pointer to the next (Box<List>)
+        Nil,
+    }
+
+    impl List {
+        // attach methods to the enum
+        fn new() -> List {
+            Self::Nil
+        }
+
+        fn prepend(self, elem: u32) -> List {
+            Self::Cons(elem, Box::new(self))
+        }
+
+        fn stringify(&self) -> String {
+            match *self {
+                Self::Cons(head, ref tail) => {
+                    format!("{} {}", head, tail.stringify()) // recursive
+                }
+                Self::Nil => {
+                    format!("Nil / End")
+                }
+            }
+        }
+    }
+
+    let mut my_list = List::new();
+
+    my_list = my_list.prepend(1);
+    my_list = my_list.prepend(2);
+    my_list = my_list.prepend(3);
+    my_list = my_list.prepend(4);
+    my_list = my_list.prepend(5);
+
+    println!("My linked list: {}", my_list.stringify());
+
+    #[derive(Debug)]
+    struct MyNewPoint<T> {
+        x: i32,
+        y: T,
+    }
+
+    let my_custom_point = MyNewPoint { x: 20, y: 10 };
+    println!("A T type point {:?}", my_custom_point);
+
+    // consts
+    const MYCONST: i32 = 10;
+    //static : possibly mutable variable with 'static lifetime
+    static MYSTATIC: &str = "Rust";
+
+    let a_number = 5;
+    println!(
+        "{} is {}",
+        a_number,
+        if a_number > MYCONST { "big" } else { "small" }
+    );
+}

src/helloworld.rs

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+pub fn hello_world_module() {
+    // Basic arguments
+    println!(
+        "{0} {1} {exclamation_argument} {exclamation_argument}",
+        "Hello",
+        "world",
+        exclamation_argument = "!"
+    );
+
+    // Numeric arguments formating
+    println!("Base 10 {}", 261);
+    println!("Base 2 (binary) {:b}", 261);
+    println!("Base 8 (octal) {:0}", 261);
+    println!("Base 16 (hexadecimal) {:x}", 261);
+
+    // Justify text
+    println!("{text:>10}", text = "right");
+    println!("{text:0>10}", text = "right");
+    println!("{text:<10}", text = "left");
+    println!("{text:0<width$}", text = "left", width = 10);
+
+    // With actual variables
+    let number: usize = 5;
+    let another: usize = 2;
+    println!("{number} {another}");
+
+    // Print structure types: fmt::Debug and "{:#?}"
+    #[derive(Debug)]
+    struct Person<'a> {
+        name: &'a str,
+        age: u8,
+    }
+
+    let peter = Person {
+        name: "Peter",
+        age: 20,
+    };
+    println!("{:#?}", peter);
+
+    // A better way of printing structured data is by customizing the outputm with fmt::Display
+    // this code should not be inside main nor a function, but will keep it here to maintain a sequential order
+    use std::fmt; // import the fmt module
+
+    // NOTE: if you want to avoid writing fmt::... every time, it  can also be destructured in the
+    // import: use std::fmt::{self, Formatter, Display};
+
+    struct Structure(i32);
+
+    // implement the fmt::Display in order to use the {} marker
+    impl fmt::Display for Structure {
+        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+            write!(f, "My structure formated: {}", self.0)
+        }
+    }
+
+    let my_structure = Structure(1);
+    println!("{}", my_structure);
+
+    // Display list example
+    // we'll use the ? operator:
+    // write!(f, "{}", value)?;
+    // Explanation: try to run write!, if it errors return the error, otherwise continue
+    // This is the proper way of handling the posible error what return fmt::Result (returned by
+    // the write!()
+    struct List(Vec<i32>);
+
+    impl fmt::Display for List {
+        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+            // Extract the value using tuple indexing,
+            // and create a reference to `vec`.
+            let vec = &self.0;
+
+            write!(f, "[")?;
+
+            // Iterate over `v` in `vec` while enumerating the iteration
+            // count in `count`.
+            for (count, v) in vec.iter().enumerate() {
+                // For every element except the first, add a comma.
+                // Use the ? operator to return on errors.
+                if count != 0 {
+                    write!(f, ", ")?;
+                }
+                write!(f, "{}: {}", count, v)?;
+            }
+
+            // Close the opened bracket and return a fmt::Result value.
+            write!(f, "]")
+        }
+    }
+
+    let v = List(vec![1, 2, 3]);
+    println!("{}", v);
+
+    // Formating can be specified via traits, there is one trait for each argument type (b,x,o,X,
+    // ...)
+    // The default argument {} is formated with the Display trait
+
+    struct City {
+        name: &'static str,
+        lat: f32,
+        lon: f32,
+    }
+
+    impl fmt::Display for City {
+        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+            let lat_c = if self.lat >= 0.0 { 'N' } else { 'S' };
+            let lon_c = if self.lon >= 0.0 { 'E' } else { 'W' };
+
+            write!(
+                f,
+                "{}: {:.3}°{} {:.3}°{}",
+                self.name,
+                self.lat.abs(),
+                lat_c,
+                self.lon.abs(),
+                lon_c
+            )
+        }
+    }
+
+    let salamanca = City {
+        name: "Salamanca",
+        lat: 53.34778,
+        lon: -6.259722,
+    };
+
+    println!("{}", salamanca)
+}

src/main.rs

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+// normal comment
+/*
+ * Multi-line comment
+ */
+// : /// Doc comment: generate library docs for the following item
+// : //! Doc comment
+
+//mod helloworld;
+//mod primitives;
+//mod customtypes;
+//mod variablebindings;
+mod types;
+
+fn main() {
+    //helloworld::hello_world_module();
+    //primitives::primitives_module();
+    //customtypes::custom_types_module();
+    //variablebindings::variable_bindings_module();
+    types::types_module();
+}

src/primitives.rs

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+#![allow(dead_code)]
+
+fn reverse_tuple(pair: (i32, bool)) -> (bool, i32) {
+    let (int_param, bool_param) = pair;
+
+    (bool_param, int_param)
+}
+
+pub fn primitives_module() {
+    // Scalar types
+    // signed integers: i8, i16, i132, 164, i128
+    // signed integers: u8, u16, u132, u64, u128
+    // floating point: f32, f64
+    // char
+    // bool
+    // unit type (), only posible value is an empty tuple
+    ////
+    // Compound types
+    // Array [1,2,3]
+    // Tuples (1, true)
+
+    let logical = true; // not necesary to specify the type if initialized
+    let a_float: f64 = 1.0;
+    let rare_integer = 5i32; // suffix annotation, = integer of 32 bits with a value of 5
+    println!("{} {} {}", logical, a_float, rare_integer);
+
+    // All are inmutable by default
+    // mut keyword
+    let mut mutable_int = 12i32;
+    println!("int: {}", mutable_int);
+    mutable_int = 21;
+    println!("int mutated: {}", mutable_int);
+
+    let mutable_int = true; // variables can be overwritten with shadowing
+    println!("not an int anymore {}", mutable_int);
+
+    let thousand = 1_000;
+    println!(
+        "1_000 is a good way to express {} in order to make it readable",
+        thousand
+    );
+
+    let cientific = 7.6e-4;
+    println!(
+        "Cientific notation is also valid, as 7.6e-4 would be stored as {}",
+        cientific
+    );
+
+    println!(
+        "Remember that the type can be specified with the number, as 1u32 is {}",
+        1u32
+    );
+
+    let my_tuple = (1, "corcho", true);
+
+    println!(
+        "The second value of the tuple {:?} is {}",
+        my_tuple, my_tuple.1
+    );
+
+    let another_tuple = (1i32, false);
+    println!(
+        "A function can also receive and return tuples, such as reverse return {:?} on {:?}",
+        reverse_tuple(another_tuple),
+        another_tuple
+    );
+
+    #[derive(Debug)]
+    struct EmulatedMatrix(f32, f32, f32, f32);
+
+    let matrix = EmulatedMatrix(1.1, 1.4, 0.5, 7.3);
+    println!("Simulated: {:?}", matrix);
+    let EmulatedMatrix(a, b, c, d) = matrix;
+    println!("Data can also be destructured: {}, {}, {}, {}", a, b, c, d);
+
+    // EXERCISE 1: fmt::Display Matrix (make it easy, you dont know loops yet)
+    println!("EXERCISE 1: Print a matrix with the tuple struct:");
+    use std::fmt::{Display, Formatter, Result};
+
+    impl Display for EmulatedMatrix {
+        fn fmt(&self, f: &mut Formatter) -> Result {
+            write!(f, "({}, {})\n({} {})", &self.0, &self.1, &self.2, &self.3)
+        }
+    }
+
+    println!("{}", matrix);
+
+    // EXERCISE 2: transpose a EmulatedMatrix (make it easy, you dont know loops yet)
+    println!("EXERCISE 2: make a simple transpose function (later on we'll improve it with loops)");
+    fn transpose(m: EmulatedMatrix) -> EmulatedMatrix {
+        let EmulatedMatrix(a, b, c, d) = m;
+        return EmulatedMatrix(a, c, b, d);
+    }
+
+    println!("{}", transpose(matrix));
+
+    // Arrays
+    let mut onetofive: [i8; 5] = [1, 2, 3, 4, 5];
+    println!("The fourth element is {}", onetofive[3]);
+    let allthrees: [i32; 10] = [3; 10];
+    println!(
+        "All threes: {:?} have a size of {}",
+        allthrees,
+        allthrees.len()
+    );
+
+    use std::mem;
+    println!("All threes accupies {} bytes", mem::size_of_val(&allthrees));
+
+    // Sclice: pointer to a portion of an array
+    // '&' means borrowing
+    let onetothree = &mut onetofive[1..3];
+    println!("One to three slice {:?}", onetothree);
+    onetothree[1] = 7;
+    println!("onetofive slice {:?} after mutating onetothree", onetofive);
+
+    for i in 0..onetofive.len() + 1 {
+        // force a failure
+        match onetofive.get(i) {
+            Some(xval) => println!("{}: {}", i, xval),
+            None => println!("Slow down! {} is too far!", i),
+        }
+    }
+}

src/types.rs

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+pub fn types_module() {
+    // casting with as: types can be casted as long as the types overlap.
+    let decimal = 65.4321;
+    let integer: u8 = decimal as u8;
+
+    println!("The decimal {} is casted to the u8 {}", decimal, integer);
+
+    // dangerous carting can be done with some methods
+    unsafe {
+        println!(
+            "f32 -100.0 as u8 is : {}",
+            (-100.0_f32).to_int_unchecked::<u8>()
+        );
+    }
+
+    // type alias are also a thing
+    type Inch = u64;
+    let inch: Inch = 5;
+    println!("using type aliases {}", inch);
+}

src/variablebindings.rs

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+pub fn variable_bindings_module() {
+    // mutability: variables are immutable by default
+    // we can say they are Frozen by default
+    let mut mutable_number = 1;
+
+    mutable_number += 1;
+    println!("number mutated: {}", mutable_number);
+
+    // scope: variables have block scope, and can be shadowed
+    let shadowed_variable = 1;
+
+    {
+        let shadowed_variable = 2;
+        println!("shadowed inside block: {}", shadowed_variable);
+    }
+    println!("shadowed outside block: {}", shadowed_variable);
+
+    // declare first approach: you can declare first and initialize later, but its not recommended.
+    let my_binding;
+
+    my_binding = 2;
+
+    println!(
+        "A variable can be initialized later even if the declaration has no type: {}",
+        my_binding
+    );
+}