Rust core · Ruby commands · Terminal

Rust keeps your text safe. Ruby makes the editor yours.

Rust owns the text, the edit history and the terminal. Ruby defines commands, keymaps and configuration. Change a command, reload it, and keep editing the same buffer.

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Architecture

Ruby never holds the text. A command reads a bounded view from the Rust core and returns a change; the core checks it and publishes it, or rejects it whole.

Rust core: Immutable UTF-8 snapshots with exact byte, scalar and UTF-16 positions, LF lines and Unicode 17 grapheme boundaries. Owns revisions, undo and redo.
Ruby runtime: Embedded CRuby 3.4. Commands read bounded pages of a snapshot and compose private edits, with nested rollback, that commit as one change.
Terminal: The first frontend. Renders only what changed, and restores the terminal's screen, modes and settings on exit, including after errors.

Commands are Ruby files

A command is a Ruby callable registered by name. A keymap binds it to keys for one interaction profile. This file wraps the current line in brackets and binds it to Control-b.

examples/terminal-commands.rb

module Ruru::UserCommands
  def self.surround_current_line(context)
    line = context.current_line
    context.replace(line.merge('replacement' => "[#{line.fetch('text')}]"))
  end
end

configuration = Ruru.configuration
configuration.command('surround-current-line',
  Ruru::UserCommands.method(:surround_current_line), {
    'description' => 'Surround the current logical line with brackets',
    'kind' => 'compound', 'requires' => 'view',
    'effects' => ['text', 'selection']
  })
configuration.keymap('user-editing', {
  'profile' => 'nonmodal', 'states' => 'editing',
  'class' => 'user', 'priority' => 10
})
configuration.bind('user-editing', ['control-b'], 'surround-current-line')

One undo step. The whole command is undone with Control-z, however many edits it made.
Reload in place. Edit the file and run reload-configuration. The buffer and its history stay.
Failed reloads change nothing. If the new file is invalid, the previous commands and profile keep working.
Inspectable. describe-key shows which binding wins and where it was declared.

What it does

Everything below is a command, so all of it can be rebound, inspected or replaced from Ruby.

Editing: Cursor movement, selection and deletion work on graphemes, so emoji and combining marks behave as one character. Nonmodal or Normal/Insert profiles. Undo and redo treat each command as one step, whether it ran in Rust or Ruby.
Files and buffers: Open, switch and save local files. Saves are atomic: a failed write never leaves a half-written file. Closing or exiting with unsaved changes asks first. A buffer list saves or closes marked buffers together.
Search: Search and replace with plain text or regular expressions, across one buffer or a whole project.
Version control: Inspect Git status and history, stage files or hunks, commit, and work with branches and conflicts.
Structured documents: Outlines, tables, tasks, agendas, source blocks and export.
Language support: Ruby, Rust, Go, TypeScript, JavaScript, HTML and CSS. Syntax works without a language server; a configured server adds completion, diagnostics, navigation and formatting.
Programming: Write commands in Ruby, find them with Alt-x, bind them to keys and reload them during a session. describe-key and describe-command show what runs and where it was declared.
Packages: Install packages from catalogs, choose their permissions, and enable, update or roll them back.

Build it

Build from source with Rust 1.98, CRuby 3.4 with its headers and shared library, a C compiler and libclang. No gems are needed.

shell

$ git clone https://forge.adrianpk.com/ruru/ruru.git
$ cd ruru
$ env -u RUBYOPT -u RUBYLIB -u GEM_HOME -u GEM_PATH \
    cargo run --locked -p ruru-editor --bin ruru-terminal-proof -- \
    --config examples/terminal-commands.rb

Ruby environment overrides are rejected at startup, so the command clears them for this process only. Control-q exits and restores the terminal.

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