Backend Effects

throw ends the current path with a failure.
log takes a non-empty literal event name and one optional payload expression.
cache supports get, set, and delete with a 15-minute default set TTL.

Throwing A Failure

code

1throw "Expense could not be processed"

A throw terminates the current control-flow path. There is no public try, catch, or finally syntax in Nenu.

Logging

code

1log("Starting room balance rebuild")2log("Finished room balance rebuild", total)

log takes a non-empty string literal event name followed by at most one payload expression. Use it for stable execution milestones and useful diagnostic context—not as a substitute for a return value, user-visible toast, or durable record.

Need	Use
Backend diagnostic milestone	`log("EventName", optional_payload)`
Visible page feedback	`toast.success`, `toast.warning`, or `toast.error`
API success data	`return Response { ... }`
Durable audit history	A project entity saved explicitly

Cache Operations

code

1cache.set("room-summary", summary)2cache.set("room-summary", summary, 3600)3cache.set("room-summary", summary, "1day")4cache.set("room-summary", summary, expires: "1day")56cache.get("room-summary")7cache.delete("room-summary")

Operation	Meaning
`cache.set(key, value)`	Store with the default TTL of 15 minutes.
`cache.set(key, value, seconds)`	Store with a numeric TTL in seconds.
`cache.set(key, value, duration)`	Store with a supported duration string.
`cache.get(key)`	Read the cached entry.
`cache.delete(key)`	Remove the cached entry.

Common Mistakes

Wrong	Correct
`print("done")`	`log("done")`
`try { ... } catch { ... }`	Validate first and use `throw` for failure.
Use `log` for a user message	Use a Page Script toast.
Put cache reads in `need {}`	Call cache operations in runnable logic.
Use cache as the only copy of an expense	Persist authoritative data as entities.

Continue Learning

Cron Runnables Apply backend effects in scheduled work.Page Effects And Handlers Use the browser-safe effect model instead.