What is ArchLang?

ArchLang is a deterministic DSL and compiler for floor plans. You describe a plan in plain text; the compiler produces a clean, deterministic drawing in SVG, DXF or PDF, with linting and geometric validation.

Edit the source below and watch it recompile live — this runs the real compiler in your browser. It is the whole of examples/one-room.arch: a shell, one room that says what it is for, a door and a window pinned to the wall by position rather than coordinate, and one dimension chain. Change 5000x4000 and watch the dimension follow.

SOURCE / .ARCH

# The smallest complete ArchLang plan: one room, one door, one window, one dimension chain.
# Every other example is this file with more of it — a shell you can walk into, a room that
# knows what it is for, and openings pinned to the wall by position rather than coordinate.
plan "One Room" {
  units mm
  grid 50
  north up
  dims auto overall
  wall id=shell exterior thickness 200 { (0,0) (5000,0) (5000,4000) (0,4000) close }
  room id=r_main at (0,0) size 5000x4000 label "Room" uses living
  door   id=d_in on shell at 60% width 900  swing in   # 60% of the loop's run: the south wall
  window id=w_n  on shell at 10% width 1500            # 10%: the north wall
  title { project "One Room" drawn_by "ArchLang" date "2026-08-16" }
}

# The smallest complete ArchLang plan: one room, one door, one window, one dimension chain. # Every other example is this file with more of it — a shell you can walk into, a room that # knows what it is for, and openings pinned to the wall by position rather than coordinate. plan "One Room" { units mm grid 50 north up dims auto overall wall id=shell exterior thickness 200 { (0,0) (5000,0) (5000,4000) (0,4000) close } room id=r_main at (0,0) size 5000x4000 label "Room" uses living door id=d_in on shell at 60% width 900 swing in # 60% of the loop's run: the south wall window id=w_n on shell at 10% width 1500 # 10%: the north wall title { project "One Room" drawn_by "ArchLang" date "2026-08-16" } }

1 rooms · 1 doors · 1 windows · 20 m²

Core ideas

• Millimetres, top-left origin, +x right, +y down (matches SVG).
• Explicit and parametric — every element has exact coordinates and sizes, so the same source always renders the same drawing, and changing one number changes exactly one thing.
• Deterministic — there is no runtime, no clock, and no randomness; loops and conditionals expand while the drawing is built. See ADR 0003.
• Zero-dependency core — the SVG path needs nothing installed. PNG, PDF, and angled-wall geometry are optional, lazily-loaded add-ons. See ADR 0002.
• Reads its own plans — archlang describe returns rooms, areas, adjacencies, and a modelled access graph; archlang lint flags habitability problems. Both are image-free facts and advice, never an auto-arranger. See Analysis.

Install & use

npm i -g @chanmeng666/archlang     # puts `archlang` on your path

No install at all: write npx -y @chanmeng666/archlang wherever this page writes archlang. The package also installs arch as an alias, but on Linux, macOS and Git Bash that name is the coreutils command, so the docs never use it.

# Compile to any format:
archlang compile plan.arch -o plan.svg              # SVG (default, zero-dep)
archlang compile plan.arch -f dxf -o plan.dxf       # DXF (zero-dep)
archlang compile plan.arch -f txt                   # ASCII plan on stdout (zero-dep)
archlang compile plan.arch -f pdf -o plan.pdf       # PDF (needs optional pdfkit)
archlang compile plan.arch -f png -o plan.png       # PNG (needs optional @resvg/resvg-js)

# Inspect and correct it:
archlang describe plan.arch --json                   # rooms, areas, adjacency, access graph — as data
archlang lint plan.arch --json                       # architectural soundness warnings
archlang validate plan.arch --strict                 # the ship-gate: valid AND sound
archlang fix plan.arch --dry-run                     # preview the machine-applicable diagnostic fixes
archlang fmt plan.arch --write                       # format in place

That is a slice — the CLI has 20 commands. Ask it about any one of them with archlang <cmd> --help (flags and worked examples for that command); archlang help lists them all and archlang --version prints the version. The full, always-current list (every flag, format and exit code) is the CLI reference, generated from the same manifest that archlang manifest --json serves — the manifest the help itself is rendered from.

Or call it as a library (npm install @chanmeng666/archlang in your project):

import { compile } from "@chanmeng666/archlang";
const { svg, diagnostics, scene } = compile(source);

Where to next

• The full language reference covers every element, value, and control-flow construct.
• Relational placement lets rooms position themselves relative to one another.
• Furniture & fixtures covers placing pieces by coordinate or snapped against a wall, and the fixture symbol catalogue.
• Analysis: describe & lint explains the semantic summary, the access graph, and the soundness rules — the channel an AI agent uses to verify a plan.
• The error catalog documents every diagnostic with a cause and a fix.
• Examples shows complete plans and their rendered output.