Homebrew Tap for Express Engine (eengine)

Table of Contents

• Purpose
• Installation
  • Add the tap
  • Install eengine
  • Verify installation
  • Update to latest version
• Supported Platforms
• How It Works
  • Automated Updates
  • Manual Formula Generation
• Repository Structure
• Development
  • Prerequisites
  • Setup
  • Testing
• Contributing
• License

Purpose

This repository provides a Homebrew tap for installing Express Engine (eengine) on macOS and Linux systems.

Express Engine is an open-source EXPRESS language parser and interpreter implemented in Steel Bank Common Lisp (SBCL).

Installation

Add the tap

brew tap expresslang/eengine

Install eengine

brew install eengine

Verify installation

eengine --version

Update to latest version

brew upgrade eengine

Supported Platforms

The formula supports the following platforms:

• macOS (Apple Silicon)

• macOS (Intel)

• Linux (x86-64)

• Linux (ARM64)

The formula automatically detects your platform and installs the appropriate binary.

How It Works

Automated Updates

This tap is automatically updated when new eengine releases are published:

1. A new release is created in eengine-releases

2. The release workflow triggers a repository_dispatch event to this repository

3. The update-formula.yml workflow runs generate-formula.rb to:

   • Download all platform binaries from the release

   • Calculate SHA256 checksums

   • Update formula-metadata.json

   • Generate Formula/eengine.rb from the ERB template

4. A pull request is created with the updated formula

5. After review and merge, the new version is available via Homebrew

Manual Formula Generation

To manually update the formula (for testing or maintenance):

# Install dependencies
bundle install

# Generate formula for a specific version
bundle exec ruby generate-formula.rb --version eeng-5.2.7

# Dry run (preview changes without writing files)
bundle exec ruby generate-formula.rb --version eeng-5.2.7 --dry-run

Repository Structure

homebrew-eengine/
├── .github/workflows/
│   └── update-formula.yml       # Automated formula update workflow
├── Formula/
│   └── eengine.rb               # Generated Homebrew formula
├── templates/
│   └── eengine.rb.erb           # ERB template for formula
├── formula-metadata.json        # Version and SHA256 metadata
├── generate-formula.rb          # Formula generator script
├── Gemfile                      # Ruby dependencies
└── README.adoc                  # This file

Development

Prerequisites

• Ruby 3.2 or later

• Bundler

Setup

# Install dependencies
bundle install

# Set GitHub token for testing (optional)
export GITHUB_TOKEN=your_token_here

Testing

Test the formula locally before publishing:

# Install from local tap
brew install --build-from-source Formula/eengine.rb

# Test the installation
eengine --version

# Uninstall
brew uninstall eengine

Contributing

This repository is primarily maintained through automated workflows. Manual updates should only be necessary for:

• Updating the formula template (templates/eengine.rb.erb)

• Modifying the generator script (generate-formula.rb)

• Fixing workflow issues

License

This tap is provided as-is for distributing eengine via Homebrew. Refer to the eengine-releases repository for license information about eengine itself.