Egg Smalltalk 🥚

Egg is a MIT-licensed implementation of a Smalltalk-80 derived environment. Egg is not strictly a ST80 though. Some egg characteristics and intentions are:

• It is module-based, where each module has its own namespace (no Smalltalk globals anymore).
• Modules can be loaded quickly through image segments (without requiring a compiler).
• It is minimal, with the capability to grow dynamically: its kernel has much fewer things than ST80 (i.e. no GUI and no compiler), but because of image-segments those modules can be loaded instantly.
• Most identifiers are dynamically bound. This means that like #doesNotUnderstand: message, you can also get a #doesNotKnow: message. The implementation uses a cache and is fast (you don't have to worry about performance there :).
• Module dependencies are stated explicitly, new modules are built through importing components of other modules.
• Designed to support multiple VMs that allow running on multiple platforms.
• This includes native JIT-based VMs for popular OSes and JS-based runtimes.
• For all VMs and OSes, the same Smalltalk code base is used (there might only be small differences if the platform used doesn't support a particular feature).
• Egg is developed in tandem with Webside, which is the GUI used to develop and debug the Smalltalk code on any platform. This allows to keep Egg minimal, even in platforms such as EggNOS (a successor of SqueakNOS!)

Contents of this repo

This repository includes the Smalltalk sources of Egg (in modules directory) as well as the different runtime implementations (runtimes directory). Some runtimes allow to generate Egg images from files, i.e. to bootstrap images (currently only possible from runtime/pharo).

Using

If you just want to use egg, download the corresponding build artifact from releases. Currently, our only working platforms are Pharo and JS, native ones will come soon™. You'll find supported platforms in /runtime subdirectories. Look for individual README.md on each of them to find specific help about using that platform.

Each subdir of runtime implements a VM that can run Egg code in a different platform. All platforms use the same Egg code, which is stored in modules directory. For now we have the following runtimes:

• Egg/Pharo - Our main platform for bootstrapping and modifying Egg kernel.
• Egg/CPP - An implementation of an Egg VM in C++. It runs on any platform for which there is a C++ compiler.
• Egg/JS - An implementation of a VM for Egg that can run in node.js or a web browser.

Building

To build egg from scratch you will need make and some tools that vary depending on your target platform (i.e. CMake and a C++ compiler for the cpp VM, Pharo for the egg VM that runs on top of Pharo, node.js if you want to host your egg in JavaScript as a server). In a nutshell, clone this repo and follow the steps provided in the respective platform READMEs in runtime subdirs.

git clone git@github.com:powerlang/egg.git
make <platform>

where platform can be js, cpp or lmr (only js works right now, we are actively working in supporting the other two).

Project status

There are (at least) two mostly orthogonal sides in this project: runtimes and Egg Smalltalk modules. In the Egg Smalltalk axis, we already have: kernel, compiler, modules and image-segment builder, among others. In runtime axis, we started using Pharo as a dev platform as it is the easiest to get working (it already includes a GC and JIT), then also implemented a VM for egg in JS, one in C++ and also an LMR (a Live Metacircular VM Runtime, a.k.a. a Smalltalk-in-Smalltalk VM).

We haven't done a 1.0 release yet, so expect a bumpy road if trying egg in the short term, the code is in alpha state.