It's not obvious how to run examples after editing — it's explained in readme.md, but I didn't see it the book itself.

[It's Ctrl-Enter. Actuallghy just pressing Ctrl is enough.]

Ideas to make it more discoverable: - re-run an expresion when the editor is unfocused. - add a "▶" button in the corner of each editor. - add a tooltip with the kbd shortcut on the "▶" button