Polywell

A highly-configurable text editor / coding tool written in Fennel and Lua that runs on the LÖVE game engine.

Originally written for Bussard, the spaceflight programming adventure.

Rationale

To say that Polywell is an editor is a little bit misleading; it may be better to think of it as an interface that allows in-game coding either to tighten the feedback loop during development or allow the player to take their customizations to the next level by writing their own code that calls functions from a sandboxed game API. But its mode-based keybinding system can also be used as controls for your game.

Polywell comes with example config which defines a special editor mode that works as a Fennel repl. However, none of that is hard-coded in; the repl mode simply binds the enter key to a function which calls the Fennel compiler on the provided input and prints the return value. But you can build many kinds of text-centric interfaces using Polywell buffers; for instance the game Bussard includes a mail reading interface as well as a simulated SSH client.

The ideal means of user empowerment is to give your users the same tools inside the program that you used to create the program yourself; this is the vision behind Polywell.

Features

• Syntax highlighting for Lua, Fennel, and Clojure; extensible to add more
• Multiple buffers
• Rebindable key commands
• Configurable by writing Fennel or Lua code
• Live completion when opening files or changing buffers
• As-you-type search
• User-definable modes which can inherit settings
• Easy to sandbox/embed
• Comes with a console for running Fennel or Lua code
• Undo
• Indentation
• Fuzzy matched opening of files and switching buffers
• Emacs key bindings (optional)

Usage

There are basically three ways to use Polywell. You can use it as a standalone text editor by just running love /path/to/polywell in your project directory. You can also embed it in your game in order to allow you to write your game from the inside out as it were, and experiment with changes to the code directly while running the game and reloading. See the game Liquid Runner for an example of a game written from inside Polywell. Finally, you can embed it in your game inside a sandboxed evaluation context and integrate it into your game in a way that allows the game's players to write their own code that can control the game. See Bussard for an example of a game that does this. There is also a sandbox_example.lua file which shows a simpler example of how to do this.

Using Polywell for in-game coding can be a bit tricky because typical Lua idioms often make reloading difficult. You have to be very intentional about keeping all your state in a single table and have some mechanism to replace all the functions without resetting the state. The lume.hotswap function may be useful here.

See the reference manual for more detailed coverage of Polywell's API.

Dependencies

• lume
• utf8.lua
• fennel
• fnlfmt
• luafilesystem (optional)

If you don't have luafilesystem then the editor will work, but the completion when you try to open new files will be inoperable.

The required dependencies are already included in the Polywell source.

License

Copyright © 2015-2019 Phil Hagelberg

Released under the terms of the GNU Lesser General Public License version 3 or later; see the file LICENSE.