chip/group

This module helps group different Subjects under a name to later reference or broadcast messages to them.

Types

Message

opaque </>

This is the message type used internally by group.

When building out your system it may be useful to state the group types on startup. For example:

let assert Ok(server) = chat.start()
let server: process.Subject(Chat)

type Topic {
  General
  OffTopic
  Cats
}

let assert Ok(registry) = group.start()
let registry: process.Subject(group.Message(Topic, Chat))

By specifying the types we can document the kind of registry we are working with; in the example above we can tell we’re creating different “chat servers” under different topic groups.

pub opaque type Message(group, msg)

Functions

dispatch

</>

pub fn dispatch(
  registry: Subject(Message(a, b)),
  group: a,
  callback: fn(Subject(b)) -> c,
) -> Nil

Executes a callback for all Subjects under a named group.

Example

> group.dispatch(registry, "group-a", fn(subject) { 
>   process.send(subject, Message(data))
> })
Nil

members

</>

pub fn members(
  registry: Subject(Message(a, b)),
  group: a,
) -> List(Subject(b))

Looks up Subjects under a named group.

Example

> group.find(registry, "group-a") 
[subject_1, subject_2, subject_3]

register

</>

pub fn register(
  registry: Subject(Message(a, b)),
  subject: Subject(b),
  group: a,
) -> Nil

Registers a Subject under a shared name.

Example

> group.register(registry, process.new_subject(), "group-a")
Nil

start

</>

pub fn start() -> Result(Subject(Message(a, b)), StartError)

Starts the registry.

Example

> group.start()
Ok(registry)