README.md

September 3, 2026 · View on GitHub

███████╗███╗   ███╗ █████╗  ██████╗███████╗       █████╗ ██████╗ ██████╗
██╔════╝████╗ ████║██╔══██╗██╔════╝██╔════╝      ██╔══██╗██╔══██╗██╔══██╗
█████╗  ██╔████╔██║███████║██║     ███████╗█████╗███████║██████╔╝██████╔╝
██╔══╝  ██║╚██╔╝██║██╔══██║██║     ╚════██║╚════╝██╔══██║██╔══██╗██╔══██╗
███████╗██║ ╚═╝ ██║██║  ██║╚██████╗███████║      ██║  ██║██║  ██║██████╔╝
╚══════╝╚═╝     ╚═╝╚═╝  ╚═╝ ╚═════╝╚══════╝      ╚═╝  ╚═╝╚═╝  ╚═╝╚═════╝

CI Docs Report Emacs License: MIT

[EMACS MAJOR MODE // NEON FONT-LOCK // PIPE DASHBOARDS // RUN + LSP]

"Open a .arb. Widgets, query verbs, and the whole pipeline spec light up."

Emacs major mode (arb-mode) for arb, the pipe-native TUI/web dashboard language on fusevm/JIT — pipe a stream in and arb builds a dynamic ratatui TUI or a served web page from a declarative, Tcl/Tk-flavored spec (a jq/xpath/css/yq superset). Font-lock for keywords, input sources, directives, widget verbs, 154 query verbs, widget paths, -flags, and /regex/ literals; filetype detection; brace-aware indentation; run a buffer through arb; eldoc + completion for verbs and widgets; and LSP via arb --lsp (eglot + lsp-mode).

Read the Docs · Engineering Report · arb · vim-arb · vscode-arb

[0x00] OVERVIEW

emacs-arb is the Emacs major mode for arb (the arb engine). It provides:

  • Filetype detection — *.arb files (auto-mode-alist) and arb shebangs (interpreter-mode-alist).
  • Syntax highlighting — font-lock for arb keywords and constants, the 10 input sources (in, in.json, in.csv, …), the 9 directives (source, bind, grid, …), the 19 widget verbs (text, table, gauge, …), the 154 query verbs (field, where, tally, sma, …), widget/control paths (.a.b.c), -flags, /regex/ literals, single- and double-quoted strings, # comments, and numbers.
  • Indentation — brace-aware indent-line-function.
  • Run — arb-run-buffer (C-c C-c) runs the buffer's spec through arb via compile.
  • eldoc + completion — one-line signatures and completion-at-point for arb verbs and widgets.
  • Language server — arb --lsp via eglot (built in since Emacs 29) and lsp-mode.

arb's builtin surface (inputs, directives, widgets, and query verbs) is small and fixed by the language, so the keyword lists are plain regexp-opt lists in arb-mode.el — no generated hash-table stdlib is needed (that machinery only exists in the sibling emacs-stryke because stryke's ~10,493 builtins overflow Emacs' regexp compiler). Verb / widget signatures for eldoc / completion live in arb-stdlib.el, authored from arb's own LSP completion corpus.

arb --lsp is launched with only --lsp — an appended --stdio is rejected by the binary, so neither client is configured to add one.

Created by MenkeTechnologies.

[0x01] FEATURE MATRIX

CapabilityStatus
Filetype detection — *.arbImplemented — auto-mode-alist
Filetype detection — shebangImplemented — interpreter-mode-alist (arb)
Syntax highlightingImplemented — font-lock for keywords, inputs, directives, widgets, verbs, paths, flags, regex
CommentsImplemented — # line comments via syntax table
StringsImplemented — single- and double-quoted via syntax table
/regex/ literalsImplemented — syntax-propertize (operand position only)
IndentationImplemented — brace-aware arb-indent-line
Run bufferImplemented — arb-run-buffer (C-c C-c) via compile
eldocImplemented — verb / widget signatures
CompletionImplemented — completion-at-point over verbs / widgets
Language server (eglot)Implemented — arb --lsp
Language server (lsp-mode)Implemented — registered client
Configarb-executable, arb-indent-offset

The arb binary must be on $PATH to run buffers and for the language server. Build arb (cargo install --path .).

[0x02] INSTALL

Manual

;; clone, then:
(add-to-list 'load-path "/path/to/emacs-arb")
(require 'arb-mode)

use-package + built-in VC

(use-package arb-mode
  :mode "\\.arb\\'"
  :vc (:url "https://github.com/MenkeTechnologies/emacs-arb"))

Open any .arb file — it lights up. Press C-c C-c to run it through arb. With eglot, run M-x eglot to start the language server (or (add-hook 'arb-mode-hook #'eglot-ensure)).

[0x03] SYNTAX // FACES

Token groupFace
Keywords / constants (fn let if for match spawn out true nil)font-lock-keyword-face
Directives (source bind grid search timeout expect)font-lock-keyword-face
Input sources (in in.json in.csv in.html in.yaml)font-lock-type-face
Widget verbs (text table gauge bars spark chart select)arb-widget-face
Query verbs (field where tally sort_by percentile sma)font-lock-builtin-face
Actions (alert beep exec flash quit)font-lock-type-face
Widget / control paths (.a .a.b.c)arb-widget-path-face
Option flags (-label -max -cols -color)arb-flag-face
Function names (fn NAME)font-lock-function-name-face
Strings / comments / /regex/via syntax table + syntax-propertize

[0x04] RUN

arb-run-buffer (bound to C-c C-c) runs the current buffer's spec through arb FILE using Emacs' compile, so output, errors, and next-error navigation land in the *compilation* buffer. The executable is arb-executable (default "arb"). arb reads its stream from stdin; pipe a producer into Emacs' inferior process or run headless from a shell for live data.

[0x05] LANGUAGE SERVER

arb-mode registers arb --lsp for both clients (lazily, so neither is a hard dependency):

  • eglot (Emacs 29+): M-x eglot in a .arb buffer.
  • lsp-mode: M-x lsp.

The executable is arb-executable (default "arb"); change it for a custom path. The server is launched with --lsp only — no --stdio is appended (the binary rejects it).

[0x06] LAYOUT

emacs-arb/
├── arb-mode.el             # major mode: syntax table, font-lock, indent, run, LSP, eldoc, completion
├── arb-stdlib.el           # verb / widget signatures (eldoc + completion)
├── scripts/face-test.el    # fontifies a sample and asserts faces
├── tests/face-test.sh      # byte-compile + face assertions wrapper
└── tests/*.sh              # README / docs / workflow validators

[0x07] LICENSE

MIT © MenkeTechnologies