Macro when 

macro_rules! when {
    ( $junction:ident; $initial_channel:ident, $( $other_channels:ident ),* ) => { ... };
}

An alternate syntax for defining Join Pattern channel constrains.

The when macro allows for a number of channels to be defined using a list like syntax, opposed to the standard method chaining provided by the default Public API of Rusty Junctions.

Example

Standard API

By using the standard Public API we can define our computation using the following syntax.

let junction = rusty_junctions::Junction::new();
let chan1 = junction.send_channel::<i32>();
let chan2 = junction.send_channel::<i32>();
let chan3 = junction.send_channel::<i32>();

junction.when(&chan1)
    .and(&chan2)
    .and(&chan3)
    .then_do(|v1, v2, v3| println!("{v1}, {v2}, {v3}"))

when Macro API

However, it is also possible to use this richer more expressive syntax, when creating the firing conditions for a Join Pattern.

let junction = rusty_junctions::Junction::new();
let chan1 = junction.send_channel::<i32>();
let chan2 = junction.send_channel::<i32>();
let chan3 = junction.send_channel::<i32>();

when!(junction; chan1, chan2, chan3)
    .then_do(|v1, v2, v3| println!("{v1}, {v2}, {v3}"))