40.1 Open the source program you just learned🔗ℹ

From the repository root, open the maintained example:

(require animate/preview)

(open-program-preview

"examples/source-block-hot-reload.rkt"

'hot-reload-demo)

The filename identifies the module. The second argument identifies its exported source program. Saving changes reloads the program while retaining unchanged blocks before the changed one. This is called hot reloading.

The complete program itself is still tested headlessly in Add blocks when you need frequent edits; only the GUI launch is intentionally excluded from the Scribble evaluator.

40.2 Review a short interval🔗ℹ

Use Play and the playhead to look at the motion. Shift-drag marks a review range; Play range runs it once and Loop range repeats it. The block selector jumps to the named blocks in the source program. Section and cue selectors appear only when that kind of information exists.

A quickly superseded frame request is not an error: you may have moved the playhead again before the earlier picture was ready. The Diagnostics control shows what was requested and what was actually displayed.

40.3 Inspect an object🔗ℹ

Select an object to inspect its identity and properties. Colored inspection outlines and dependency arrows belong to the preview. They do not become objects in the Scene or appear in the final movie.

For formula source selection, cancellation outcomes, audio monitoring, and worker recovery, use Preview controls and diagnostics. Those details are kept in Reference so they do not interrupt this first editing session.