Absytree

This is still very early in developement and very experimental!

Written in Nim

Programming Language + Editor

Absytree is a text editor + programming languange workbench where instead of writing the source code as text in text files, the abstract syntac tree (AST) is edited directly (or rather through projections, which are still trees) Languages will be extendable with custom AST node types, by either translating those to nodes of other languages or by implementing code generation for the backend (at the moment only WASM).

The editor is available for the terminal, as a desktop GUI app and in the browser. You can try the browser version here (old version). There is also a very experimental Unreal Engine Plugin.

ast is the gui version, astt is the terminal version

Goals

For the text editor:
- Sit somewhere inbetween Vim and VS Code
- The most important tools are built in (e.g. syntax highlighting with tree-sitter, LSP support)
- Can be used purely as a text editor (ignoring the AST language framework)
- Little to no configuration needed to get nice experience out of the box
- Support Vim motions
General goals:
- Keyboard focused (only basic mouse support)
- Easily extendable with scripting
- Good performance

Inspirations

Building

Setup

Requires OpenGL 4.1 for the GUI version
Install Nim version 2.0.2. (we need some file from the compiler source so you need to install nim using choosenim, the prebuilt binaries from the nim website or build nim from source, because some linux package repositories, e.g. arch, don't seem to include the compiler source code, which this editor needs for nimscript)
Clone the repository
Run nimble setup

By default builds will not include the nimscript plugin api and the ast language framework. To enable these features pass -D:enableNimscript=true and -D:enableAst=true respectively.

Desktop version

Use nimble buildDesktop or nimble build to compile the desktop version of the editor.
The release builds are built with:
- For the gui version: nimble buildDesktop --app:gui -D:forceLogToFile -D:enableGui=true -D:enableTerminal=false
- For the terminal version: nimble buildDesktop --app:console -D:forceLogToFile -D:enableGui=false -D:enableTerminal=true

Browser version

Run nimble buildBrowser
Embed the generated file ast.js
See absytree_browser.html for an example

Compiling tree sitter grammars to wasm

Go into the tree-sitter repositories root directory
Make sure the cli is built
- cargo build
Compile the desired language to wasm. The specified directory is the one containing the src folder which in turn contains the grammar.js
- target/release/tree-sitter build-wasm ../dev/nimtreesitter/treesitter_nim/treesitter_nim/nim

Compiling tree sitter wasm binding

Go into the tree-sitter repositories root directory
Build the binding:
- script/build-wasm
Copy the generated files to the AbsytreeBrowser directory:
- cp lib/binding_web/tree-sitter.js <.../AbsytreeBrowser> && cp lib/binding_web/tree-sitter.wasm <.../AbsytreeBrowser>

Configuration

options.json

options.json contains simple values which are used by the editor. This file is automatically created when exiting the editor with the current options. When the editor launches it loads the current options from this file again (before running any scripts/plugins)

Scripts/Plugins

Absytree supports different scripting languages/mechanisms. The editor API is exposed to each one and can be used to create new commands, change options, etc.

NimScript: Only supported in the desktop version. The editor bundles part of the Nim compiler so it can run NimScript code. Allows easy hot reloading of the config file, but right now only one nimscript file is supported. Slightly increases startup time of the editor.
Wasm: Works on the desktop and in the browser. In theory any language can be used to write plugins if it can compile to wasm. Probably better performance than NimScript.
In the future the builtin language framework will be usable as a scripting language as well by compiling to wasm.

At startup Absytree loads the following scripts in order:

config/absytree_config_wasm.wasm
config/absytree_config.nim (NimScript, only in desktop version)

At the moment config/absytree_config_wasm.wasm is generated from config/absytree_config.nim by compiling it to wasm using config/config.nims (uses Emscripten). So absytree_config.nim can be used as NimScript or as a wasm plugin.

The editor API is exactly the same in both cases.

Inside absytree_config.nim one can check if it's being used in wasm or NimScript using the following check:

when defined(wasm):
  # Script was compiled to wasm
else:
  # Script is being interpreted as NimScript

absytree_config.nim must import absytree_runtime, which contains some utility functions. absytree_runtime also exports absytree_api, which contains every function exposed by the editor. absytree_api is automatically generated when compiling the editor.

There are a few utility scripts for defining key bindings.

import keybindings_normal: Standard keybindings, like most text editors. (e.g. no modes)
import keybindings_vim: Vim inspired keybindings, work in progress. Will probably never be 100% compatible.
import keybindings_helix: Helix inspired keybindings, work in progress. Will probably never be 100% compatible.

Each of these files defines a load*Bindings() function which applies the corresponding key bindings. After calling this function one can still override specific keys.

More details in Getting Started