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Getting started


Phel requires PHP 8.0 or higher and Composer.

Quick start#

To get started right away, you can use the cli-skeleton project on GitHub.

git clone https://github.com/phel-lang/cli-skeleton.git
composer install
# Start the REPL to try Phel
./vendor/bin/phel repl

More information can be found in the Readme of the project.

Manually initialize a new project using Composer#

The easiest way to get started is by setting up a new Composer project. First, create a new directory and initialize a new Composer project.

mkdir hello-world
cd hello-world
composer init

Composer will ask a bunch of questions that can be answered as in the following example.

Welcome to the Composer config generator

This command will guide you through creating your composer.json config.

Package name (<vendor>/<name>): phel-lang/hello-world
Description []:
Author [Your Name <your.name@domain.com>, n to skip]:
Minimum Stability []:
Package Type (e.g. library, project, metapackage, composer-plugin) []: project
License []:

Define your dependencies.

Would you like to define your dependencies (require) interactively [yes]? no
Would you like to define your dev dependencies (require-dev) interactively [yes]? no

    "name": "phel-lang/hello-world",
    "type": "project",
    "authors": [
            "name": "Your Name",
            "email": "your.name@domain.com"
    "require": {}

Do you confirm generation [yes]? yes

Next, require Phel as a dependency.

# Require and install Phel
composer require phel-lang/phel-lang

First, create a phel config file, called phel-config.php in the root of the project:


return (new \Phel\Config\PhelConfig())

Read the docs for Configuration to see all available configuration options for Phel.

Then, create a new directory src with a file boot.phel inside this directory.

mkdir src

The file boot.phel contains the actual code of the project. It defines the namespace and prints "Hello, World!".

# in src/boot.phel
(ns hello-world\boot)

(println "Hello, World!")

Running the code#

There are two ways to run the code: from the command line and with a PHP Server.

From the Command line#

Code can be executed from the command line by calling the vendor/bin/phel run command, followed by the file path or namespace:

vendor/bin/phel run src/boot.phel
# or
vendor/bin/phel run hello-world\\boot
# or
vendor/bin/phel run "hello-world\boot"

The output will be:

Hello, World!

With a PHP Server#

Check the web-skeleton project on GitHub.

The file index.php will be executed by the PHP Server. It initializes the Phel Runtime and loads the namespace from the boot.phel file described above, to start the application.

// src/index.php

use Phel\Phel;

$projectRootDir = __DIR__ . '/../';

require $projectRootDir . 'vendor/autoload.php';

Phel::run($projectRootDir, 'hello-world\\boot');

The PHP Server can now be started.

# Start server
php -S localhost:8000 ./src/index.php

In the browser, the URL http://localhost:8000 will now print "Hello, World!".

Launch the REPL#

To try Phel you can run a REPL by executing the ./vendor/bin/phel repl command.

Read more about the REPL in its own chapter.

Editor support#

Phel comes with basic support for VSCode, PhpStorm, a Emacs mode with interactive capabilities and a Vim plugin in the making.