There is a particular kind of software nostalgia that still earns its place: LOGO's turtle, reduced to movement, repetition, and a trail left behind.

zago brings that idea into a terminal Markdown editor. It is written by zonble, and the interesting part is not a separate graphics window. The text buffer itself becomes the canvas.

A zago LOGO turtle drawing recorded with Tapedeck

The pen is a text-buffer mode

zago's Editor LOGO uses the familiar PD and PU commands:

  • PD — pen down; movement leaves line-drawing characters in the buffer.
  • PU — pen up; movement becomes safe navigation again.
  • FD — move forward in the current direction.
  • RT and LT — turn right or left by 90 degrees.

When the pen is down, zago does more than print independent characters. It merges horizontal and vertical strokes into Unicode junctions such as ┌, ┐, └, ┘, and ┼. That makes a sequence of cursor movements behave like a small diagram editor while the result remains plain text.

The default is deliberately safe: LOGO execution starts with the pen up. A macro has to opt into drawing explicitly, and a finished drawing should lift the pen again.

A small polygon instead of BOX

The official pen-mode guide already demonstrates a square with BOX-like movement. For this recording I used a stepped octagon so the demo shows turtle movement without repeating that example:

PD FD 16 RT 90 FD 8 RT 90 FD 6 RT 90 FD 3
RT 90 FD 4 RT 90 FD 3 RT 90 FD 6 RT 90 FD 8 PU

zago's turns are 90-degree turns, so this is not a graphical regular octagon. It is an orthogonal text polygon: a sequence of straight moves and right-angle turns that closes back on itself. The shape is less important than the mechanism — the turtle moves, the buffer records the path, and junction characters are fused as the path changes direction.

The same command can be tested without opening the editor:

zago -e 'PD FD 16 RT 90 FD 8 RT 90 FD 6 RT 90 FD 3 RT 90 FD 4 RT 90 FD 3 RT 90 FD 6 RT 90 FD 8 PU'

That headless mode is useful for checking a drawing before putting it into an interactive recording. It also makes the output easy to inspect in a shell or pipeline.

Recording the interaction instead of recording it again

I used Tapedeck to turn the terminal session into a repeatable .roll script. The script is named examples/tui_zago_logo_turtle.roll in the Tapedeck repository and describes the boring parts explicitly:

Set Engine Auto
Set Output "zago_logo_turtle.gif"
Set FPS 15
...
Escape
Type "PD FD 16 RT 90 FD 8 RT 90 FD 6 RT 90 FD 3 RT 90 FD 4 RT 90 FD 3 RT 90 FD 6 RT 90 FD 8 PU"
Enter

tapedeck run --dry-run examples/tui_zago_logo_turtle.roll passes the parser and selects the VHS engine. Running the script produced a 1200×600 GIF with 251 frames in the local recording environment. The output is a terminal capture, not a claim that zago opens a graphical turtle canvas.

That distinction matters. zago owns the editor and the LOGO language; Tapedeck only makes the interaction reproducible. If the recording needs a new shape later, the script is the source of the demo instead of a sequence of manually timed keystrokes.

A small downstream contribution

I also maintain aur-zago, an Arch Linux packaging project for zago. The intended AUR package name is zago-bin; it is not published in the AUR yet because new account registration is currently unavailable to me. This is downstream work, not zago development. I packaged it because I am a fan of zonble's project and wanted a convenient Arch installation path; the zago design, implementation, and authorship remain zonble's.

That boundary is worth stating plainly when writing about tools one did not create. Packaging, recording, and documenting a project can be useful without turning into an ownership claim.

Sources