glixir 🌟

Seamless OTP interop between Gleam and Elixir/Erlang

Bridge the gap between Gleam’s type safety and the battle-tested OTP ecosystem. Use GenServers, Supervisors, Agents, Registry, and more from Gleam with confidence.

Features

• ✅ GenServer - Type-safe calls to Elixir GenServers
• ✅ DynamicSupervisor - Runtime process supervision and management
• ✅ Agent - Simple state management with async operations
• ✅ Registry - Dynamic process registration and Subject lookup
• 🚧 Task - Async task execution (coming soon)
• 🚧 Phoenix.PubSub - Distributed messaging (coming soon)
• ✅ Zero overhead - Direct BEAM interop with clean Elixir helpers
• ✅ Gradual adoption - Use alongside existing Elixir code

Installation

gleam add glixir

Add the Elixir helper modules to your project:

# lib/glixir_supervisor.ex and lib/glixir_registry.ex
# Copy the helper modules from the docs

Quick Start

Registry - Dynamic Actor Discovery

The game-changer for building scalable actor systems! 🎯

import glixir
import gleam/erlang/process

pub type UserMessage {
  RecordMetric(name: String, value: Float)
  GetStats
}

pub fn actor_discovery_example() {
  // Start registry for actor lookup
  let assert Ok(_registry) = glixir.start_registry("user_actors")
  
  // Start supervisor for dynamic actors
  let assert Ok(supervisor) = glixir.start_supervisor_simple()
  
  // Spawn a user actor dynamically
  let user_spec = glixir.child_spec(
    id: "user_123",
    module: "MyApp.UserActor", 
    function: "start_link",
    args: [dynamic.string("user_123")]
  )
  
  let assert Ok(user_pid) = glixir.start_child(supervisor, user_spec)
  
  // Actor registers itself in the registry
  let user_subject = process.new_subject()
  let assert Ok(_) = glixir.register_subject("user_actors", "user_123", user_subject)
  
  // Later... find and message the actor from anywhere!
  case glixir.lookup_subject("user_actors", "user_123") {
    Ok(subject) -> {
      process.send(subject, RecordMetric("page_views", 1.0))
      io.println("Metric sent to user actor! 📊")
    }
    Error(_) -> io.println("User actor not found")
  }
}

Perfect for:

• 🎯 Metrics platforms - Find user actors by ID
• 🎮 Game servers - Locate player sessions
• 💬 Chat systems - Route messages to user connections
• 📊 Real-time dashboards - Dynamic process coordination

DynamicSupervisor

import glixir

pub fn main() {
  // Start a named dynamic supervisor
  let assert Ok(supervisor) = glixir.start_supervisor_named("my_supervisor", [])
  
  // Create a child specification
  let worker_spec = glixir.child_spec(
    id: "worker_1",
    module: "MyApp.Worker",
    function: "start_link", 
    args: [dynamic.string("config")]
  )
  
  // Start a child process
  case glixir.start_child(supervisor, worker_spec) {
    Ok(pid) -> io.println("Worker started!")
    Error(reason) -> io.println("Failed to start worker: " <> reason)
  }
  
  // List all children
  let children = glixir.which_children(supervisor)
  io.debug(children)
  
  // Get child counts
  let counts = glixir.count_children(supervisor)
  io.debug(counts)
}

GenServer Interop

import glixir

pub fn main() {
  // Start an Elixir GenServer from Gleam
  let assert Ok(server) = glixir.start_genserver("MyApp.Counter", dynamic.int(0))
  
  // Type-safe calls with custom decoders
  let assert Ok(count) = glixir.call_genserver(server, dynamic.string("get"), decode.int)
  io.debug(count)  // 0
  
  // Cast messages (fire and forget)
  let assert Ok(_) = glixir.cast_genserver(server, dynamic.string("increment"))
  
  // Call again to see the change
  let assert Ok(count) = glixir.call_genserver(server, dynamic.string("get"), decode.int)
  io.debug(count)  // 1
  
  // Stop the GenServer
  let assert Ok(_) = glixir.stop_genserver(server)
}

Agent State Management

import glixir
import gleam/dynamic/decode

pub fn main() {
  // Start an agent with initial state
  let assert Ok(counter) = glixir.start_agent(fn() { 42 })
  
  // Get state with a decoder
  let assert Ok(value) = glixir.get_agent(counter, fn(x) { x }, decode.int)
  io.debug(value)  // 42
  
  // Update state
  let assert Ok(_) = glixir.update_agent(counter, fn(n) { n + 10 })
  
  // Get and update in one operation
  let assert Ok(old_value) = glixir.get_and_update_agent(
    counter, 
    fn(n) { #(n, n * 2) },
    decode.int
  )
  io.debug(old_value)  // 52
  
  // Stop the agent
  let assert Ok(_) = glixir.stop_agent(counter)
}

Working with Elixir Modules

Creating an Elixir Worker

# lib/my_app/worker.ex
defmodule MyApp.Worker do
  use GenServer
  
  def start_link(config) do
    GenServer.start_link(__MODULE__, config)
  end
  
  def init(config) do
    {:ok, %{config: config, count: 0}}
  end
  
  def handle_call(:get_count, _from, state) do
    {:reply, state.count, state}
  end
  
  def handle_cast(:increment, state) do
    {:noreply, %{state | count: state.count + 1}}
  end
end

Using from Gleam

import glixir
import gleam/dynamic
import gleam/dynamic/decode

pub fn worker_example() {
  // Start the supervisor
  let assert Ok(sup) = glixir.start_supervisor_named("worker_supervisor", [])
  
  // Create worker specification  
  let worker_spec = glixir.child_spec(
    id: "my_worker",
    module: "MyApp.Worker",
    function: "start_link",
    args: [dynamic.string("some_config")]
  )
  
  // Start the worker under supervision
  let assert Ok(worker_pid) = glixir.start_child(sup, worker_spec)
  
  // Interact with the worker using GenServer calls
  let assert Ok(count) = glixir.call_genserver(
    worker_pid, 
    dynamic.atom("get_count"), 
    decode.int
  )
  io.debug(count)  // 0
  
  // Send a cast message
  let assert Ok(_) = glixir.cast_genserver(worker_pid, dynamic.atom("increment"))
  
  // Check the count again
  let assert Ok(count) = glixir.call_genserver(
    worker_pid, 
    dynamic.atom("get_count"), 
    decode.int
  )
  io.debug(count)  // 1
}

Advanced Patterns

Scalable Actor System with Registry

import glixir
import gleam/erlang/process
import gleam/dynamic

pub type MetricMessage {
  Record(name: String, value: Float, user_id: String)
  Subscribe(subject: process.Subject(String))
}

pub fn metrics_platform_example() {
  // Infrastructure setup
  let assert Ok(_) = glixir.start_registry("metric_actors")
  let assert Ok(_) = glixir.start_registry("user_sessions") 
  let assert Ok(supervisor) = glixir.start_supervisor_named("metrics_supervisor", [])
  
  // Spawn metric collector actor
  let metric_spec = glixir.child_spec(
    id: "metric_collector",
    module: "MyApp.MetricCollector",
    function: "start_link", 
    args: []
  )
  
  let assert Ok(_metric_pid) = glixir.start_child(supervisor, metric_spec)
  
  // When a user connects, spawn their personal actor
  let user_id = "user_12345"
  let user_spec = glixir.child_spec(
    id: user_id,
    module: "MyApp.UserActor",
    function: "start_link",
    args: [dynamic.string(user_id)]
  )
  
  let assert Ok(_user_pid) = glixir.start_child(supervisor, user_spec)
  
  // User actor registers itself
  let user_subject = process.new_subject()
  let assert Ok(_) = glixir.register_subject("user_sessions", user_id, user_subject)
  
  // From anywhere in the system - send metrics to user
  case glixir.lookup_subject("user_sessions", user_id) {
    Ok(subject) -> {
      process.send(subject, Record("page_view", 1.0, user_id))
      io.println("✅ Metric routed to user actor!")
    }
    Error(_) -> io.println("❌ User session not found")
  }
  
  // Cleanup when user disconnects
  let assert Ok(_) = glixir.unregister_subject("user_sessions", user_id)
  let assert Ok(_) = glixir.terminate_child(supervisor, user_id)
}

Worker Pool Pattern

import glixir
import gleam/list
import gleam/int

pub fn start_worker_pool(pool_size: Int) {
  let assert Ok(supervisor) = glixir.start_supervisor_named("worker_pool", [])
  
  // Start multiple workers
  list.range(1, pool_size)
  |> list.map(fn(i) {
    let worker_spec = glixir.child_spec(
      id: "worker_" <> int.to_string(i),
      module: "MyApp.PoolWorker", 
      function: "start_link",
      args: [dynamic.int(i)]
    )
    
    glixir.start_child(supervisor, worker_spec)
  })
  |> list.all(fn(result) {
    case result {
      Ok(_) -> True
      Error(_) -> False
    }
  })
}

Fault-Tolerant Services

import glixir

pub fn start_resilient_service() {
  let assert Ok(supervisor) = glixir.start_supervisor_named("app_supervisor", [])
  
  // Start critical services with permanent restart
  let cache_spec = glixir.worker_spec("cache", "MyApp.Cache", [])
  let database_spec = glixir.worker_spec("database", "MyApp.Database", [])
  
  // Start optional services with temporary restart
  let metrics_spec = glixir.SimpleChildSpec(
    ..glixir.worker_spec("metrics", "MyApp.Metrics", []),
    restart: glixir.temporary
  )
  
  let assert Ok(_) = glixir.start_child(supervisor, cache_spec)
  let assert Ok(_) = glixir.start_child(supervisor, database_spec)
  let assert Ok(_) = glixir.start_child(supervisor, metrics_spec)
  
  supervisor
}

Configuration

Restart Strategies

import glixir

// Permanent: Always restart (default)
let permanent_worker = glixir.SimpleChildSpec(
  ..glixir.worker_spec("critical", "MyApp.Critical", []),
  restart: glixir.permanent
)

// Temporary: Never restart
let temporary_worker = glixir.SimpleChildSpec(
  ..glixir.worker_spec("temp", "MyApp.TempWorker", []),
  restart: glixir.temporary
)

// Transient: Restart only on abnormal termination
let transient_worker = glixir.SimpleChildSpec(
  ..glixir.worker_spec("transient", "MyApp.Transient", []),
  restart: glixir.transient
)

Custom Timeouts

import glixir

let custom_spec = glixir.SimpleChildSpec(
  ..glixir.worker_spec("custom", "MyApp.Custom", []),
  shutdown_timeout: 10000,  // 10 seconds to shutdown gracefully
  restart: glixir.permanent
)

Registry API Reference

// Start a unique registry (most common)
let assert Ok(registry) = glixir.start_registry("my_processes")

// Register a Subject by key  
let subject = process.new_subject()
let assert Ok(_) = glixir.register_subject("my_processes", "worker_1", subject)

// Look up Subject by key
case glixir.lookup_subject("my_processes", "worker_1") {
  Ok(found_subject) -> process.send(found_subject, MyMessage)
  Error(glixir.NotFound) -> io.println("Process not found")
  Error(_) -> io.println("Registry error")
}

// Clean up
let assert Ok(_) = glixir.unregister_subject("my_processes", "worker_1")

Type Safety Notes

While this library provides type-safe wrappers on the Gleam side, remember:

1. Runtime Types: Elixir/Erlang processes are dynamically typed at runtime
2. Message Contracts: Ensure message formats match between Gleam and Elixir
3. Decoder Functions: Always provide appropriate decoders for return values
4. Error Handling: Handle all potential decode and process errors
5. Testing: Test integration points thoroughly

Error Handling

import glixir

pub fn robust_worker_start() {
  case glixir.start_supervisor_named("robust_sup", []) {
    Ok(supervisor) -> {
      let spec = glixir.worker_spec("worker", "MyApp.Worker", [])
      
      case glixir.start_child(supervisor, spec) {
        Ok(pid) -> {
          io.println("Worker started successfully")
          Ok(#(supervisor, pid))
        }
        Error(reason) -> {
          io.println("Failed to start worker: " <> reason)
          Error("worker_start_failed")
        }
      }
    }
    Error(_supervisor_error) -> {
      io.println("Failed to start supervisor")
      Error("supervisor_start_failed")
    }
  }
}

Real-World Use Cases

TrackTags - Auto-scaling metrics platform built with glixir:

• ✅ Dynamic user actors spawned per session
• ✅ Registry-based actor discovery by user ID
• ✅ Real-time metric collection and coordination
• ✅ Fault-tolerant supervision trees

“glixir made building a distributed metrics platform feel like writing normal Gleam code. The Registry system is a game-changer for actor coordination!”

About the Author

Built by Rahmi Pruitt - Ex-Twitch/Amazon Engineer turned indie hacker, on a mission to bring Gleam to the mainstream! 🚀

I believe Gleam’s type safety + Elixir’s battle-tested OTP = the future of fault-tolerant systems. This library bridges that gap, making OTP’s superpowers accessible to Gleam developers.

Connect with me:

• 💼 LinkedIn
• 🐦 Follow my Gleam journey and indie hacking adventures

“Making concurrent programming delightful, one type at a time.”

⭐ Star this repo if glixir helped you build something awesome! Your support helps bring mature OTP tooling to the Gleam ecosystem.