Macro prob 

macro_rules! prob {
    ($e:expr) => { ... };
    (let $var:ident <- $expr:expr; $($rest:tt)*) => { ... };
    (let $var:ident = $expr:expr; $($rest:tt)*) => { ... };
    ($expr:expr; $($rest:tt)*) => { ... };
}

Probabilistic programming macro, used to define probabilistic programs with do-notation.

Example:

let model = prob! {
    let x <- sample(addr!("x"), Normal::new(0.0, 1.0).unwrap());
    let y <- sample(addr!("y"), Normal::new(x, 1.0).unwrap());
    pure(y)
};