What is ArchLang?

ArchLang is a small declarative language that compiles to a professional SVG floor plan — think Typst/LaTeX, but for architecture. You describe a plan in plain text; the compiler produces a clean, deterministic drawing.

plan "Studio 1BR" {
  units mm
  grid 50
  scale 1:50
  north up

  wall exterior thickness 200 { (0,0) (7000,0) (7000,6000) (0,6000) close }
  room id=living at (0,0) size 7000x6000 label "Living / Kitchen" uses living kitchen
  door at (1000,6000) width 1000 wall exterior hinge left swing in
  window at (2500,0) width 1800 wall exterior
  furniture bed at (4300,300) size 1500x2000 label "Bed"
  dim (0,6000)->(7000,6000) offset 600 text "7000"
}

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 — arch describe returns rooms, areas, adjacencies, and a modelled access graph; arch lint flags habitability problems. Both are image-free facts and advice, never an auto-arranger. See Analysis.

Install & use

npm install @chanmeng666/archlang

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

arch fmt plan.arch --write                       # format in place
arch explain E_LAYOUT_CYCLE                       # explain a diagnostic

Or call it as a library:

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.