Paint, run, and debug Piet — the esolang where programs are abstract art. Pixel-grid editor for .piet files with live command hints, a step debugger (stack, DP/CC, breakpoints), PNG import/export, and a built-in interpreter — no external tools required.
Installation
Launch VS Code Quick Open (Ctrl+P), paste the following command, and press enter.
Create, edit, debug, and run Piet programs inside VS Code.
A .piet file is a PNG image stored at one pixel per codel. Opening one shows a paintable
color grid instead of an image preview.
Features
Grid editor for .piet files: pencil (click/drag) and paint-bucket (fill a block)
tools with the 20 Piet colors; right-click picks up a color from the grid.
Configurable grid size — resize the grid at any time from the toolbar (content is preserved).
Authoring aids — palette swatches are labeled with the command each color gives
relative to the selected color; the 👁 toggle draws those labels on the grid itself;
the status bar shows the hovered block's size (the value push would push).
Built-in debugger (DEBUGGER tab on the right edge): run animated at three speeds,
pause, single-step, run to completion, stop; live view of the DP/CC, the stack,
the last command, and program output; input can be entered before running; the current
color block and codel are highlighted on the canvas. Set breakpoints with the 📌 tool —
execution pauses when flow enters a marked cell's block. Arithmetic uses BigInt, so
values never overflow.
Import / Export toolbar buttons: load any Piet image into the grid (any codel size —
it is normalized to one pixel per codel), or export a scaled PNG for sharing.
▶ Run in terminal via the editor title bar — programs run in a terminal tab on the
extension's own interpreter (no Python or other tools needed), with interactive input:
when the program executes in(num)/in(char) you type the value right in the terminal.
Ctrl+C stops endless programs. Set piet.runCommand (e.g.
uv run python piet/piet.py {file}) to use an external interpreter instead.
Piet: New Piet File — create a blank grid of any size.
Piet: Import PNG as .piet — convert an existing Piet image to a .piet file.
Building
npm install
npm run compile
npm run package # produces piet-editor-<version>.vsix
code --install-extension piet-editor-0.3.3.vsix
Or open this folder in VS Code and press F5 for a development host.
Tests
npm test
Runs the suite under Node's built-in test runner (no extra dependencies):
test/interpreter.test.js — PietVM semantics: every arithmetic/stack command
(with sign edge cases), BigInt precision, termination rules, interactive input,
and full runs of the bundled hi/fibonnaci programs (checked through fib(100)).
test/png.test.js — PNG codec: encode/decode round trips at several codel sizes,
plus decoding of Pillow-generated fixtures (filtered RGB, 8-bit and 4-bit palette,
grayscale) verified pixel-for-pixel against Pillow's own output.
test/runner.test.js — the terminal runner with a stubbed VS Code API:
codel-size detection, program completion, output throttling, interactive
input echo, and Ctrl+C handling.
