daemon-loops.ilo

-- daemon-loops: three concurrent background loops via `spawn` (ILO-477).
--
-- `spawn fn args... > _` runs `fn args...` on a background OS thread and
-- returns Nil immediately. Errors and panics inside the thread go to
-- stderr; the parent is unaffected.
--
-- Use case: the load-bearing example is `ilo-lang/crew`'s per-machine
-- agent daemon — it needs an MCP HTTP server in the foreground, an SSE
-- consumer in the background, and a write-behind queue drainer also in
-- the background. Without `spawn` the agent has to ship three glued
-- processes; with it, a single ilo binary owns all three loops.
--
-- Out of scope for v1 (separate tickets): join handles, channels,
-- supervision, cancellation, async runtime. This is fire-and-forget by
-- design; treat each spawned loop as a long-lived process and write its
-- state to disk or send it over the wire if you need cross-thread comms.

-- ticker: print a labelled line every ~100ms for `n` iterations.
ticker label:t n:n>_
@i 0..n{prnt (fmt "{} tick {}" label i);sleep 100}

-- main: spawn three tickers and wait long enough for them to finish.
-- Output is interleaved (non-deterministic order) so we don't pin an
-- exact stdout — the example is timing-sensitive by nature.
main>_
spawn ticker "alpha" 3;spawn ticker "beta" 3;spawn ticker "gamma" 3;sleep 500;prnt "parent done"

-- run: ilo run examples/daemon-loops.ilo main
-- Expected: nine "<label> tick <n>" lines interleaved across the three
-- threads, followed by "parent done". No -- out: assertion: ordering
-- depends on the OS scheduler, so this example is excluded from the
-- examples_engines harness (cases with no -- out: are skipped).