Introduce rxRust: Reactive Extensions for Rust

rxrust: Reactive Extensions for Rust

rxrust ia a Rust implementation of Reactive Extensions.


use rxrust::{ ops::{ Filter, Merge, Fork }, prelude::*};

let mut numbers = observable::from_range(0..10).multicast();

// crate a even stream by filter

let even = numbers.fork().filter(|v| *v % 2 == 0);

// crate an odd stream by filter

let odd = numbers.fork().filter(|v| *v % 2 != 0);

// merge odd and even stream again

even.merge(odd).subscribe(|v| print!("{} ", v, ));

// "0 1 2 3 4 5 6 7 8 9" will be printed.

Fork Stream

In rxrust almost all extensions consume the upstream. So in general it is unicast. So when you try to subscribe a stream twice, the compiler will complain.

# use rxrust::prelude::*;

let o = observable::from_range(0..10);

o.subscribe(|_| {println!("consume in first")});

o.subscribe(|_| {println!("consume in second")});

In this case, we can use multicast convert an unicast stream to a multicast stream. A multicast stream is a stream that implements Fork trait, let you can fork stream from it. Subject is an multicast stream default, so you can direct fork it.

# use rxrust::prelude::*;

# use rxrust::ops::Fork;

let o = observable::from_range(0..10).multicast();

o.fork().subscribe(|_| {println!("consume in first")});

o.fork().subscribe(|_| {println!("consume in second")});


For now, only a new thread scheduler has been implemented.

use rxrust::prelude::*;

use rxrust::{ops::{ ObserveOn, SubscribeOn, Map }, scheduler };



.map(|v| *v*2)


.subscribe(|v| {println!("{},", v)});

Runtime error propagating

In rxrust, almost every extension which accept closure as argument has two version method. One version is use when no runtime error will be propagated. This version receive an normal closure. The other is use when when you want propagating runtime error, named xxx_with_err, and receive an closure that return an Result type, to detect if an runtime error occur. For example:

use rxrust::{ops::{ Map, MapWithErr }, prelude::*};

// normal version

// double a number

let subject = Subject::new();


.map(|i| 2 * i)

.subscribe(|v| print!("{} | ", v));

// runtime error version

// only double a even number. otherwise throw an error.


.map_with_err(|i| {

if i % 2 == 0 {Ok(i*2)}

else {Err("odd number should never be pass to here")}


.subscribe_err(|v| print!("{} | ", v), |err|{println!("{} | ", err)});;;

// normal version will print `0 | ` and `2 |`,

// runtime error version will print `0 | ` and `odd number should never be pass to here | "

// this example print "0 | 0 | 2 | odd number should never be pass to here | "