rust-play

extern crate num_traits;

fn generic_scalar_product<T>(v: &[T], w: &[T]) -> T
where
    // A type can implement multiple traits!
    // The + sign here means that we expect T to implement
    // both num_traits::Zero and std::ops::Mul
    T: num_traits::Zero + std::ops::Mul
{
    let length = v.len(); 

rust-play

macro_rules! read_arr {
    ($r: expr, $sz: expr) => {{
        let mut buf = [0; $sz];
        $r.read_exact(&mut buf)?;
        Ok(buf)
    }};
}

fn f(r: &mut impl std::io::Read) -> std::result::Result<(), Box<dyn std::error::Error>> {
    read_arr!(r, 8)?;

rust-play

macro_rules! read_arr {
    ($r: expr, $sz: expr) => {{
        let mut buf = [0; $sz];
        $r.read_exact(&mut buf)?;
        Ok(buf)
    }};
}

rust-play

use std::marker::PhantomData;

// T is the return type of the callback FnMut
// Phantomdata cuz the optional callback is inside an ffi struct 
struct Config<T>(PhantomData<T>);
struct ConfigBuilder<T>(PhantomData<T>);

impl<T> ConfigBuilder<T> {
    pub fn set_callback<F>(&mut self, cb: F) -> &mut Self
    where 

rust-play

use std::marker::PhantomData;

// T is the return type of the callback FnMut
// Phantomdata cuz the optional callback is inside an ffi struct 
struct Config<T>(PhantomData<T>);

enum UnboundT { }

impl Default for Config<UnboundT> {
    fn default() -> Self {

rust-play

#[derive(Copy, Clone)]
pub struct Foo(u32, u32);
pub fn foo(x: Foo) -> Option<Foo> {
    Some(x.clone())
}
pub fn bar(x: Foo) -> Option<Foo> {
    Some(x)
}

rust-play

use std::marker::PhantomData;

// T is the return type of the callback FnMut
// Phantomdata cuz the optional callback is inside an ffi struct 
struct Config<T> (PhantomData<T>);
impl<T> Config<T> {
    pub fn new() -> Self {
        Config::<T>(PhantomData)
    }
    

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use std::mem;

pub struct List {
    head: Link,
}

enum Link {
    Empty,
    More(Box<Node>),
}

rust-play

fn main() {
    let mut x: u32 = 0;
    
    unsafe {
        let ptr: *mut u32 = &mut x;
        std::ptr::drop_in_place(ptr);
        std::ptr::drop_in_place(ptr);
    }
}

rust-play

fn main() {
    println!("Hello, world!");
}