rontolisp:wait-for

(rontolisp:wait-for milliseconds)

Returns a future that settles to nil after the given number of milliseconds (a non-negative integer). The timer starts immediately, so awaiting it delays the awaiting code only -- other async bodies keep running, which makes wait-for the async counterpart of cl:sleep (which blocks and takes seconds).

Timers run concurrently: two futures started together settle in delay order, not start order, and awaiting both takes about the longer delay, not the sum.

Backend support

rontolisp:wait-for exists on the interpreter, the JVM backend and WASM --component (where it lowers to the host timer, wasi:clocks/monotonic-clock@0.3.0's wait-for, as a pending future the event loop settles -- timers genuinely overlap there too). Preview 1 WASM rejects it at compile time (no host timer).