turtle
Classic turtle graphics: a pen that moves and turns, drawing as it goes.
Backend: pure — stdlib/turtle.lynx, a thin wrapper over the graphics module's turtle state machine (rust/graphics). The drawing goes through the ordinary shape ops, so it works with a window and on the headless rasterizer. Import: import("turtle") → global.turtle.*
State lives in graphics
Lynxer has no module-level mutable state, so a pure-Lynxer module cannot remember anything between calls. The turtle therefore lives in the graphics module as a handle; this module drives the implicit default turtle (handle 0), which graphics creates on first use. Programs that need several turtles use the graphics.turtle* ops with an explicit handle from graphics.turtleCreate(x, y, heading).
The heading is in degrees: 0 points east (+x) and increases clockwise, matching the screen's y-down coordinate system.
Functions
| Function | Signature | Notes |
|---|---|---|
forward | (float distance) -> int | Move forward, drawing when the pen is down |
back | (float distance) -> int | Move backward |
turn / turnRight | (float degrees) -> int | Turn clockwise |
turnLeft | (float degrees) -> int | Turn counter-clockwise |
goto | (float x, float y) -> int | Move straight without turning |
home | () -> int | Return to the origin, facing east |
penUp / penDown | () -> int | Stop / resume drawing while moving |
setColor | (int r, int g, int b, int a = 255) -> int | Pen colour |
setWidth | (float width) -> int | Pen width in pixels |
x / y | () -> float | Current position |
heading | () -> float | Current heading in degrees |
penIsDown | () -> bool | Whether the pen is down |
Each op returns 0 on success (the movement ops) or the queried value; there is no failure sentinel because the default turtle always exists.
Example
global setup(){ import("turtle"); import("graphics"); }
global main(){
global.graphics.init("turtle", 400, 400);
global.graphics.clearBackground(255, 255, 255);
global.turtle.setColor(0, 90, 200);
global.turtle.setWidth(2.0);
for (int i = 0; i < 4; i = i + 1){
global.turtle.forward(120.0);
global.turtle.turn(90.0);
}
println(global.turtle.x(), ",", global.turtle.y());
println(global.turtle.heading());
}See also
- graphics — the drawing surface the turtle moves over, and the explicit-handle
graphics.turtle*ops. - stdlib-contracts — the contract this module implements, including the error sentinel family it uses.
- limitations — the full divergence register.