radiate

Hot reloading while in development for Gleam!

Introduction

Radiate will watch any directory you specify for changes. When a file is changed in that directory, it’ll check if it’s a Gleam file, and if it is, the project will be recompiled and all modified modules will be reloaded, without having to restart the BEAM VM.

Quick start

// On main.gleam
import gleam/erlang/process
import gleam/io
import radiate
import message

pub fn main() {
 let _ =
   radiate.new()
   |> radiate.add_dir("src")
   |> radiate.start()

 let timer_subject = process.new_subject()

 print_every_second(timer_subject)
}

fn print_every_second(subject: process.Subject(Nil)) {
 process.send_after(subject, 1000, Nil)

 let _ = process.receive(subject, 1500)
 io.println(message.get_message())

 print_every_second(subject)
}

// On message.gleam
pub fn get_message() -> String {
 "Hello!"
}

When you first run this, it’ll print “Hello!” every second.

Now, go ahead and change the text get_message returns to "Hello, world!", and save the file.

As soon as you save, the message printed is changed to “Hello, world!”, without needing to restart the program!

Adding a callback

You can add callbacks to be run every time code is reloaded through on_reload:

import radiate
import gleam/io

pub fn main() {
 let _ = radiate.new()
   |> radiate.add_dir("src")
   |> radiate.on_reload(fn (path) {
     io.println("Change in " <> path <> ", reloading!")
   })
   |> radiate.start()
}

Installation

This package can be added to your Gleam project:

gleam add radiate

and its documentation can be found at https://hexdocs.pm/reloader.