Code shared from the Rust Playground

playground.rs

pub mod person {
    use std::marker::PhantomData;
    
    #[derive(Debug)]
    pub struct Person {
        name: String,
        age: u8,
    }
    
    impl Person {
        pub fn builder() -> Builder<(), ()> {
            Builder::new()
        }
    }
    
    pub struct Builder<P1, P2> {
        name: String,
        age: u8,
        p1: PhantomData<P1>,
        p2: PhantomData<P2>,
    }
    
    impl Builder<(), ()> {
        fn new() -> Builder<(), ()> {
            Builder {
                name: String::new(),
                age: 0,
                p1: PhantomData,
                p2: PhantomData,
            }
        }
    }
    
    pub struct MarkerName;
    pub struct MarkerAge;
    
    impl<A> Builder<A, ()> {
        pub fn set_age(self, age: u8) -> Builder<A, MarkerAge> {
            Builder {
                name: self.name,
                age,
                p1: self.p1,
                p2: PhantomData,
            }
        }
    }
    
    impl<B> Builder<(), B> {
        pub fn set_name<S: AsRef<str>>(self, name: S) -> Builder<MarkerName, B> {
            Builder {
                name: name.as_ref().to_owned(),
                age: self.age,
                p1: PhantomData,
                p2: self.p2,
            }
        }
    }
    
    impl Builder<MarkerName, MarkerAge> {
        pub fn build(self) -> Person {
            Person {
                name: self.name,
                age: self.age,
            }
        }
    }
}

use self::person::Person;

fn main() {
    let person1 = Person::builder().set_age(3).set_name("ポチ").build();
    let person2 = Person::builder().set_name("タマ").set_age(5).build();
    // let person3 = Person::builder().set_name("コロ").build(); // compile error
    
    println!("{:?}", person1);
    println!("{:?}", person2);
}