CodeBlock escape

The DSL covers most simple rules. Need loops, several steps of changes or helper code? Set the do field to a CodeBlock.

In the editor, tick the CodeBlock (TS escape) box above the code editor. The body takes JavaScript-like code and sees what a DSL expression sees. Bare names are the current agent's or patch's properties and the globals. All DSL functions work, and me is the current agent or patch.

Example: flocking-style alignment

const others = neighbors(3);            // agents within 3 patches
if (others.length === 0) return;

// average heading of nearby boids
let sx = 0, sy = 0;
for (const b of others) {
  sx += Math.cos(b.heading * Math.PI / 180);
  sy += Math.sin(b.heading * Math.PI / 180);
}
const target = Math.atan2(sy, sx) * 180 / Math.PI;

// rotate 10% of the way toward the group's average heading
turn(0.1 * (target - heading));
move_forward(1);

What's allowed

Assignments, conditionals, loops (for, while), local let/const.
The full DSL function set (move_forward, neighbors, chance, ...).
Standard JS globals: Math, JSON, Array, Object, Number, String, Boolean, parseInt, parseFloat, isNaN, isFinite. These are also available in regular one-line expressions.

What's banned

await / async: a rule must finish within its tick.
eval, new Function(...), import(...): no loading of code.

A rule that uses them fails when it is read. It then shows a red ! error badge next to its name in the Code tab.