actor

Types

ErlangStartResult

An Erlang supervisor compatible process start result.

If you wish to convert this into a StartResult compatible with Gleam supervisors see the from_erlang_start_result and wrap_erlang_starter functions.

pub type ErlangStartResult =
  Result(Pid, Dynamic)

InitResult

</>

The type used to indicate whether an actor has started successfully or not.

pub type InitResult(state, message) {
  Ready(state: state, receiver: Option(Receiver(message)))
  Failed(ExitReason)
}

Constructors

```
Ready(state: state, receiver: Option(Receiver(message)))
```
The actor has successfully initialised. The actor can start handling messages and actor’s channel sender can be returned to the parent process.
```
Failed(ExitReason)
```
The actor has failed to initialise. The actor shuts down and an error is returned to the parent process.

</>

The type used to indicate what to do after handling a message.

pub type Next(state) {
  Continue(state)
  Stop(ExitReason)
}

Constructors

```
Continue(state)
```
Continue handling messages.
```
Stop(ExitReason)
```
Stop handling messages and shut down.

Spec

</>

This data structure holds all the values required by the start_spec function in order to create an actor.

If you do not need to configure the initialisation behaviour of your actor consider using the start function.

pub type Spec(state, msg) {
  Spec(
    init: fn() -> InitResult(state, msg),
    init_timeout: Int,
    loop: fn(msg, state) -> Next(state),
  )
}

Constructors

```
Spec(
  init: fn() -> InitResult(state, msg),
  init_timeout: Int,
  loop: fn(msg, state) -> Next(state),
)
```
Arguments
- init
  
  The initialisation functionality for the actor. This function is called just after the actor starts but before the channel sender is returned to the parent.
  
  This function is used to ensure that any required data or state is correct. If this function returns an error it means that the actor has failed to start and an error is returned to the parent.
- init_timeout
  
  How many milliseconds the init function has to return before it is considered to have taken too long and failed.
- loop
  
  This function is called to handle each message that the actor receives.

StartError

</>

pub type StartError {
  InitTimeout
  InitFailed(ExitReason)
  InitCrashed(Dynamic)
}

Constructors

```
InitTimeout
```
```
InitFailed(ExitReason)
```
```
InitCrashed(Dynamic)
```

StartResult

</>

The result of starting a Gleam actor.

This type is compatible with Gleam supervisors. If you wish to convert it to a type compatible with Erlang supervisors see the ErlangStartResult type and erlang_start_result function.

pub type StartResult(msg) =
  Result(Sender(msg), StartError)

Functions

call

</>

pub fn call(receiver: Sender(a), make_message: fn(Sender(b)) -> a, timeout: Int) -> b

Send a synchronous message and wait for a response from the receiving process.

If a reply is not received within the given timeout then the sender process crashes. If you wish receive a Result rather than crashing see the process.try_call function.

This is a re-export of process.call, for the sake of convenience.

from_erlang_start_result

</>

pub fn from_erlang_start_result(start: Result(Pid, a)) -> Result(
  Sender(b),
  StartError,
)

Processes written in Erlang or other BEAM languages use bare processes rather than channels, so the value returned from their process start functions are not compatible with Gleam supervisors. This function can be used to wrap the return value so it can be used with a Gleam supervisor.

pid

</>

pub fn pid(sender: Sender(a)) -> Pid

Get the pid of the receiver process for a sender.

send

</>

pub fn send(channel: Sender(a), msg: a) -> Sender(a)

Send a message over a given channel.

This is a re-export of process.send, for the sake of convenience.

start

</>

pub fn start(state: a, loop: fn(b, a) -> Next(a)) -> Result(
  Sender(b),
  StartError,
)

Start an actor with a given initial state and message handling loop function.

This function returns a Result but it will always be Ok so it is safe to use with assert if you are not starting this actor as part of a supervision tree.

If you wish to configure the initialisation behaviour of a new actor see the Spec record and the start_spec function.

start_spec

</>

pub fn start_spec(spec: Spec(a, b)) -> Result(
  Sender(b),
  StartError,
)

Start an actor from a given specification. If the actor’s init function returns an error or does not return within init_timeout then an error is returned.

If you do not need to specify the initialisation behaviour of your actor consider using the start function.

to_erlang_start_result

</>

pub fn to_erlang_start_result(res: Result(Sender(a), StartError)) -> Result(
  Pid,
  Dynamic,
)

Convert a Gleam actor start result into an Erlang supervisor compatible process start result.

wrap_erlang_starter

</>

pub fn wrap_erlang_starter(start: fn() -> Result(Pid, a)) -> fn() ->
  Result(Sender(b), StartError)

Processes written in Erlang or other BEAM languages use bare processes rather than channels, so the value returned from their process start functions are not compatible with Gleam supervisors. This function can be used to wrap the start function so it can be used with a Gleam supervisor.

Constructors

Constructors

Constructors

Arguments

Constructors