Control Flow

yield()

Pauses the current execution context until the next game tick. Works in the main coroutine, inside tick(), and inside user-created coroutines:

while true do
    local temp = ic.read(0, ic.enums.LogicType.Temperature)
    print("Temp: " .. tostring(temp))
    yield()
end

sleep(seconds)

Pauses the current execution context for a real-time duration. The runtime counts down across ticks. Works in the main coroutine, inside tick(), and inside user-created coroutines:

print("Starting...")
sleep(5)
print("5 seconds later!")

Each execution context sleeps independently — sleeping in tick() does not freeze the main coroutine, and sleeping in a user coroutine does not freeze either.

sleep() and yield() in User Coroutines

When you call sleep() or yield() inside a coroutine you created with coroutine.create(), the runtime automatically tracks and resumes it:

local function worker(name, interval)
    while true do
        print(name .. " working")
        sleep(interval)
    end
end

local fast = coroutine.create(worker)
local slow = coroutine.create(worker)
coroutine.resume(fast, "fast", 1)   -- starts, runs until first sleep(1)
coroutine.resume(slow, "slow", 5)   -- starts, runs until first sleep(5)

-- Both coroutines are now managed by the runtime.
-- "fast" resumes every ~1s, "slow" every ~5s, independently.
-- The main chunk and tick() continue running normally.

WARNING

The runtime auto-resumes sleeping user coroutines. Do not manually coroutine.resume() a coroutine that is currently sleeping — the runtime handles it. Up to 32 user coroutines can be sleeping simultaneously.

tick(dt)

If you define a global function named tick, it's called automatically every game tick. sleep() and yield() work inside it:

function tick(dt)
    -- dt = seconds since last tick (~0.5s typically)
    print("Delta: " .. dt)
end

Example with sleep inside tick():

function tick(dt)
    ic.write(0, ic.enums.LogicType.On, 1)
    sleep(2)
    ic.write(0, ic.enums.LogicType.On, 0)
    sleep(2)
end

throw(message)

Immediately throws a Lua runtime error:

throw("something went terribly wrong")

hcf()

Halt and Catch Fire — permanently destroys the chip:

hcf()  -- The chip is gone. No undo!

DANGER

hcf() is destructive and irreversible. The chip item is permanently destroyed. Use with caution (or for dramatic effect).