demo/src/ReplicatedStorage/start.luau

@@ -2,16 +2,18 @@ local ReplicatedStorage = game:GetService("ReplicatedStorage")
 local RunService = game:GetService("RunService")
 local UserInputService = game:GetService("UserInputService")
 local jabby = require(ReplicatedStorage.Packages.jabby)
-local std = ReplicatedStorage.std
+local std = require(ReplicatedStorage.std)
-local scheduler = require(std.scheduler)
+local Scheduler = std.Scheduler
-local world = require(std.world)
+local world = std.world
 
 local function start(modules)
+	local scheduler = Scheduler.new(world, require(ReplicatedStorage.std.components))
 	for _, module in modules do
-		require(module)
+		require(module)(scheduler)
 	end
-	local events = scheduler.COLLECT()
+	local events = scheduler.collect.all()
-	scheduler.BEGIN(events)
+	scheduler.systems.begin(events)
+
 	jabby.set_check_function(function(player)
 		return true
 	end)

demo/src/ReplicatedStorage/std/bt.luau

@@ -3,15 +3,15 @@
 
 -- original author @centau
 
-local FAILURE = -1 
+local SUCCESS = 0
-local RUNNING = 0 
+local FAILURE = 1
-local SUCCESS = 1 
+local RUNNING = 2
 
 local function SEQUENCE(nodes)
 	return function(...)
 		for _, node in nodes do
 			local status = node(...)
-			if status <= RUNNING  then
+			if status == FAILURE or status == RUNNING then
 				return status
 			end
 		end
@@ -23,7 +23,7 @@ local function FALLBACK(nodes)
 	return function(...)
 		for _, node in nodes do
 			local status = node(...)
-			if status > FAILURE then
+			if status == SUCCESS or status == RUNNING then
 				return status
 			end
 		end

demo/src/ReplicatedStorage/std/components.luau

@@ -8,7 +8,7 @@ local components: {
 	Model: Entity<Model>,
 	Player: Entity,
 	Target: Entity,
-	Transform: Entity<{ new: CFrame, old: CFrame }>,
+	Transform: Entity<CFrame>,
 	Velocity: Entity<number>,
 	Previous: Entity,
 } =
@@ -23,8 +23,4 @@ local components: {
 		Previous = world:component(),
 	}
 
-for name, component in components :: {[string]: jecs.Entity} do 
-	world:set(component, jecs.Name, name)
-end
-
 return table.freeze(components)

demo/src/ReplicatedStorage/std/ctx.luau

@@ -0,0 +1,11 @@
+local handle = require(script.Parent.handle)
+local world = require(script.Parent.world)
+
+local singleton = world:entity()
+
+local function ctx()
+	-- Cannot cache handles because they will get invalidated
+	return handle(singleton)
+end
+
+return ctx

demo/src/ReplicatedStorage/std/handle.luau

@@ -0,0 +1,56 @@
+local jecs = require(game:GetService("ReplicatedStorage").ecs)
+local world = require(script.Parent.world)
+
+type Handle = {
+	has: (self: Handle, id: jecs.Entity) -> boolean,
+	get: <T>(self: Handle, id: jecs.Entity<T>) -> T?,
+	add: <T>(self: Handle, id: jecs.Entity<T>) -> Handle,
+	set: <T>(self: Handle, id: jecs.Entity<T>, value: T) -> Handle,
+	id: (self: Handle?) -> jecs.Entity,
+}
+
+local handle: (e: jecs.Entity) -> Handle
+
+do
+	local e
+	local function has(_, id)
+		return world:has(e, id)
+	end
+	local function get(_, id)
+		return world:get(e, id)
+	end
+	local function set(self, id, value)
+		world:set(e, id, value)
+		return self
+	end
+	local function add(self, id)
+		world:add(e, id)
+		return self
+	end
+	local function clear(self)
+		world:clear(e)
+		return self
+	end
+	local function delete(self)
+		world:delete(e)
+	end
+	local function id()
+		return e
+	end
+
+	local entity = {
+		has = has,
+		get = get,
+		set = set,
+		add = add,
+		clear = clear,
+		id = id,
+	}
+
+	function handle(id)
+		e = id
+		return entity
+	end
+end
+
+return handle

demo/src/ReplicatedStorage/std/hooks.luau

@@ -0,0 +1,32 @@
+--!native
+--!optimize 2
+local ReplicatedStorage = game:GetService("ReplicatedStorage")
+local jecs = require(ReplicatedStorage.ecs)
+
+local function create_cache(hook)
+	local columns = setmetatable({}, {
+		__index = function(self, component)
+			local column = {}
+			self[component] = column
+			return column
+		end,
+	})
+
+	return function(world, component, fn)
+		local column = columns[component]
+		table.insert(column, fn)
+		world:set(component, hook, function(entity, value)
+			for _, callback in column do
+				callback(entity, value)
+			end
+		end)
+	end
+end
+
+local hooks = {
+	OnSet = create_cache(jecs.OnSet),
+	OnAdd = create_cache(jecs.OnAdd),
+	OnRemove = create_cache(jecs.OnRemove),
+}
+
+return hooks

demo/src/ReplicatedStorage/std/init.luau

@@ -0,0 +1,25 @@
+local jecs = require(game:GetService("ReplicatedStorage").ecs)
+
+local world = require(script.world) :: jecs.World
+export type World = jecs.World
+
+local Scheduler = require(script.scheduler)
+export type Scheduler = Scheduler.Scheduler
+
+local std = {
+	ChangeTracker = require(script.changetracker),
+	Scheduler = Scheduler,
+	bt = require(script.bt),
+	collect = require(script.collect),
+	components = require(script.components),
+	ctx = require(script.ctx),
+	handle = require(script.handle),
+	interval = require(script.interval),
+	ref = require(script.ref),
+	world = world :: World,
+	pair = jecs.pair,
+	__ = jecs.w,
+	hooks = require(script.hooks),
+}
+
+return std

demo/src/ReplicatedStorage/std/interval.luau

@@ -16,4 +16,4 @@ local function interval(s)
 	return throttle
 end
 
-return interval
+return interval

demo/src/ReplicatedStorage/std/phases.luau

@@ -1,14 +0,0 @@
-local std = game:GetService("ReplicatedStorage").std
-local Players = game:GetService("Players")
-
-local scheduler = require(std.scheduler)
-local PHASE = scheduler.PHASE
-
-return {
-    PlayerAdded = PHASE({
-        event = Players.PlayerAdded
-    }),
-    PlayerRemoved = PHASE({
-        event = Players.PlayerRemoving
-    })
-}

demo/src/ReplicatedStorage/std/ref.luau

@@ -1,18 +1,16 @@
+local handle = require(script.Parent.handle)
 local world = require(script.Parent.world)
-local jecs = require(game:GetService("ReplicatedStorage").ecs)
+local refs = {}
-local refs: {[any]: jecs.Entity} = {}
 
-local function fini(key): () -> ()
+local function fini(key)
 	return function()
 		refs[key] = nil
 	end
 end
 
-local function noop() end
+local function ref(key): (handle.Handle, (() -> ())?)
-
-local function ref(key): (jecs.Entity, () -> ())
 	if not key then
-		return world:entity(), noop
+		return handle(world:entity())
 	end
 	local e = refs[key]
 	if not e then
@@ -20,7 +18,7 @@ local function ref(key): (jecs.Entity, () -> ())
 		refs[key] = e
 	end
 	-- Cannot cache handles because they will get invalidated
-	return e, fini(key)
+	return handle(e), fini(key)
 end
 
 return ref

demo/src/ReplicatedStorage/std/registry.luau

@@ -0,0 +1,31 @@
+local reserved = 0
+
+local function reserve()
+	reserved += 1
+	return reserved
+end
+
+-- If you don't like passing around a world singleton
+-- and you need to register component IDs, just register them.
+-- I dont use this because I like adding component traits
+--[[
+    local components = {
+        Model = registry.reserve(),
+        Transform = registry.reserve(),
+    }
+
+    local world = registry.register(jecs.World.new())
+    local e = world:entity()
+    world:set(e, components.Transform, CFrame)
+]]
+local function register(world)
+	for _ = 1, reserved do
+		world:component()
+	end
+	return world
+end
+
+return {
+	reserve = reserve,
+	register = register,
+}

demo/src/ReplicatedStorage/std/scheduler.luau

@@ -1,7 +1,6 @@
 --!native
 --!optimize 2
 local ReplicatedStorage = game:GetService("ReplicatedStorage")
-local RunService = game:GetService("RunService")
 local jabby = require(ReplicatedStorage.Packages.jabby)
 local jecs = require(ReplicatedStorage.ecs)
 local pair = jecs.pair
@@ -9,7 +8,6 @@ local Name = jecs.Name
 
 type World = jecs.World
 type Entity<T = nil> = jecs.Entity<T>
-type Id<T = unknown> = jecs.Id<T>
 
 type System = {
 	callback: (world: World) -> (),
@@ -23,145 +21,226 @@ type Events = {
 	Heartbeat: Systems,
 }
 
-local world = require(script.Parent.world)
+export type Scheduler = {
-local Disabled = world:entity()
+	components: {
-local System = world:component() :: Id<{ callback: (any) -> (), name: string}>
+		Disabled: Entity,
-local DependsOn = world:entity()
+		System: Entity<System>,
-local Event = world:component() :: Id<RBXScriptSignal>
+		Phase: Entity,
-local Phase = world:entity()
+		DependsOn: Entity,
+	},
 
-local PreRender = world:entity()
+	collect: {
-local Heartbeat = world:entity()
+		under_event: (event: Entity) -> Systems,
-local PreAnimation = world:entity()
+		all: () -> Events,
-local PreSimulation = world:entity()
+	},
 
-local sys: System
+	systems: {
-local dt: number
+		begin: (events: Events) -> { [Entity]: thread },
+		new: (callback: (dt: number) -> (), phase: Entity) -> Entity,
+	},
 
-local jabby_scheduler = jabby.scheduler.create("Scheduler")
+	phases: {
+		RenderStepped: Entity,
+		Heartbeat: Entity,
+	},
 
-local a, b, c, d
+	phase: (after: Entity) -> Entity,
-local function run()
-	local id = sys.id
-	jabby_scheduler:run(id, sys.callback, a, b, c, d)
-	return nil
-end
 
-world:add(Heartbeat, Phase)
+	debugging: boolean,
-world:set(Heartbeat, Event, RunService.Heartbeat)
+}
 
-world:add(PreSimulation, Phase)
+local scheduler_new: (w: World, components: { [string]: Entity }) -> Scheduler
-world:set(PreSimulation, Event, RunService.PreSimulation)
 
-world:add(PreAnimation, Phase)
+do
-world:set(PreAnimation, Event, RunService.PreAnimation)
+	local world: World
+	local Disabled: Entity
+	local System: Entity<System>
+	local DependsOn: Entity
+	local Phase: Entity
+	local Event: Entity<RBXScriptSignal>
 
-table.insert(jabby.public, {
+	local scheduler
-	class_name = "World",
-	name = "MyWorld",
-	world = world,
-	debug = Name,
-	entities = {},
-})
 
-jabby.public.updated = true
+	local RenderStepped
+	local Heartbeat
+	local PreAnimation
+	local PreSimulation
 
-table.insert(jabby.public, jabby_scheduler)
+	local sys: System
+	local dt
 
-if RunService:IsClient() then 
+	local function run()
-	world:add(PreRender, Phase)
+		local id = sys.id
-	world:set(PreRender, Event, (RunService :: RunService).PreRender)
+		scheduler:run(id, sys.callback, dt)
-end
+	end
-
-local function begin(events: { [RBXScriptSignal]: Systems })
-	local connections = {}
-	for event, systems in events do
-		if not event then
-			continue
-		end
-		local event_name = tostring(event)
-		connections[event] = event:Connect(function(...)
-			debug.profilebegin(event_name)
-			for _, s in systems do
-				sys = s
-				a, b, c, d = ...
-
-				for _ in run do
-					break
-				end
 
+	local function panic(str)
+		-- We don't want to interrupt the loop when we error
+		task.spawn(error, str)
+	end
+	local function begin(events: { Systems })
+		local connections = {}
+		for event, systems in events do
+			if not event then
+				continue
 			end
-			debug.profileend()
+			local event_name = tostring(event)
-		end)
+			connections[event] = event:Connect(function(delta)
-	end
+				debug.profilebegin(event_name)
-	return connections
+				for _, s in systems do
-end
+					sys = s
+					dt = delta
+					local didNotYield, why = xpcall(function()
+						for _ in run do
+							break
+						end
+					end, debug.traceback)
 
-local function scheduler_collect_systems_under_phase_recursive(systems, phase: Entity)
+					if didNotYield then
-	local phase_name = world:get(phase, Name)
+						continue
-	for _, s in world:query(System):with(pair(DependsOn, phase)) do
+					end
-		table.insert(systems, {
-			id = jabby_scheduler:register_system({
-				name = s.name,
-				phase = phase_name,
-			} :: any),
-			callback = s.callback,
-		})
-	end
-	for after in world:query(Phase):with(pair(DependsOn, phase)):iter() do
-		scheduler_collect_systems_under_phase_recursive(systems, after)
-	end
-end
 
-local function scheduler_collect_systems_under_event(event)
+					if string.find(why, "thread is not yieldable") then
-	local systems = {}
+						panic(
-	scheduler_collect_systems_under_phase_recursive(systems, event)
+							"Not allowed to yield in the systems."
-	return systems
+								.. "\n"
-end
+								.. "System: "
-
+								.. debug.info(s.callback, "n")
-local function scheduler_collect_systems_all()
+								.. " has been ejected"
-	local events = {}
+						)
-	for phase, event in world:query(Event):with(Phase) do
+						continue
-		events[event] = scheduler_collect_systems_under_event(phase)
+					end
+					panic(why)
+				end
+				debug.profileend()
+			end)
+		end
+		return threads
 	end
-	return events
-end
 
-local function scheduler_phase_new(d: { after: Entity?, event: RBXScriptSignal? })
+	local function scheduler_collect_systems_under_phase_recursive(systems, phase)
-	local phase = world:entity()
+		local phase_name = world:get(phase, Name)
-	world:add(phase, Phase)
+		for _, s in world:query(System):with(pair(DependsOn, phase)) do
-	local after = d.after
+			table.insert(systems, {
-	if after then 
+				id = scheduler:register_system({
-		local dependency = pair(DependsOn, after :: Entity)
+					name = s.name,
+					phase = phase_name,
+				}),
+				callback = s.callback,
+			})
+		end
+		for after in world:query(Phase):with(pair(DependsOn, phase)) do
+			scheduler_collect_systems_under_phase_recursive(systems, after)
+		end
+	end
+
+	local function scheduler_collect_systems_under_event(event)
+		local systems = {}
+		scheduler_collect_systems_under_phase_recursive(systems, event)
+		return systems
+	end
+
+	local function scheduler_collect_systems_all()
+		local events = {}
+		for phase, event in world:query(Event):with(Phase) do
+			events[event] = scheduler_collect_systems_under_event(phase)
+		end
+		return events
+	end
+
+	local function scheduler_phase_new(after)
+		local phase = world:entity()
+		world:add(phase, Phase)
+		local dependency = pair(DependsOn, after)
 		world:add(phase, dependency)
+		return phase
 	end
-	
-	local event = d.event
-	if event then 
-		world:set(phase, Event, event)
-	end
-	return phase
-end
 
-local function scheduler_systems_new(callback: (any) -> (), phase: Entity?) 
+	local function scheduler_systems_new(callback, phase)
-	local system = world:entity()
+		local system = world:entity()
-	world:set(system, System, { callback = callback, name = debug.info(callback, "n") })
+		local name = debug.info(callback, "n")
-	local depends_on = DependsOn :: jecs.Entity
+		world:set(system, System, { callback = callback, name = name })
-	local p: Entity = phase or Heartbeat
+		world:add(system, pair(DependsOn, phase))
-	world:add(system, pair(depends_on, p))
+		return system
-	
+	end
-	return system
+
+	function scheduler_new(w: World, components: { [string]: Entity })
+		world = w
+		Disabled = world:component()
+		System = world:component()
+		Phase = world:component()
+		DependsOn = world:component()
+		Event = world:component()
+
+		RenderStepped = world:component()
+		Heartbeat = world:component()
+		PreSimulation = world:component()
+		PreAnimation = world:component()
+
+		local RunService = game:GetService("RunService")
+		if RunService:IsClient() then
+			world:add(RenderStepped, Phase)
+			world:set(RenderStepped, Event, RunService.RenderStepped)
+		end
+
+		world:add(Heartbeat, Phase)
+		world:set(Heartbeat, Event, RunService.Heartbeat)
+
+		world:add(PreSimulation, Phase)
+		world:set(PreSimulation, Event, RunService.PreSimulation)
+
+		world:add(PreAnimation, Phase)
+		world:set(PreAnimation, Event, RunService.PreAnimation)
+
+		for name, component in components do
+			world:set(component, Name, name)
+		end
+
+		table.insert(jabby.public, {
+			class_name = "World",
+			name = "MyWorld",
+			world = world,
+			debug = Name,
+			entities = {},
+		})
+
+		jabby.public.updated = true
+		scheduler = jabby.scheduler.create("scheduler")
+
+		table.insert(jabby.public, scheduler)
+
+		return {
+			phase = scheduler_phase_new,
+
+			phases = {
+				RenderStepped = RenderStepped,
+				PreSimulation = PreSimulation,
+				Heartbeat = Heartbeat,
+				PreAnimation = PreAnimation,
+			},
+
+			world = world,
+
+			components = {
+				DependsOn = DependsOn,
+				Disabled = Disabled,
+				Phase = Phase,
+				System = System,
+			},
+
+			collect = {
+				under_event = scheduler_collect_systems_under_event,
+				all = scheduler_collect_systems_all,
+			},
+
+			systems = {
+				new = scheduler_systems_new,
+				begin = begin,
+			},
+		}
+	end
 end
 
 return {
-	SYSTEM = scheduler_systems_new,
+	new = scheduler_new,
-	BEGIN = begin,
-	PHASE = scheduler_phase_new, 
-	COLLECT = scheduler_collect_systems_all,
-	phases = {
-		Heartbeat = Heartbeat,
-		PreSimulation = PreSimulation,
-		PreAnimation = PreAnimation,
-		PreRender = PreRender
-	}
 }

demo/src/ServerScriptService/systems/mobs.luau

@@ -6,12 +6,13 @@ local ReplicatedStorage = game:GetService("ReplicatedStorage")
 local blink = require(game:GetService("ServerScriptService").net)
 local jecs = require(ReplicatedStorage.ecs)
 local __ = jecs.Wildcard
-local std = ReplicatedStorage.std
-local ref = require(std.ref)
-local interval = require(std.interval)
 
-local world = require(std.world)
+local std = require(ReplicatedStorage.std)
-local cts = require(std.components)
+local ref = std.ref
+local interval = std.interval
+
+local world: std.World = std.world
+local cts = std.components
 
 local Mob = cts.Mob
 local Transform = cts.Transform
@@ -19,26 +20,13 @@ local Velocity = cts.Velocity
 local Player = cts.Player
 local Character = cts.Character
 
-local characters = world
-	:query(Character)
-	:with(Player)
-	:cached()
-
-
-local moving_mobs = world
-	:query(Transform, Velocity)
-	:with(Mob)
-	:cached()
-	
-
 local function mobsMove(dt: number)
 	local targets = {}
-
+	for _, character in world:query(Character):with(Player):iter() do
-	for _, character in characters do
 		table.insert(targets, (character.PrimaryPart :: Part).Position)
 	end
 
-	for mob, transform, v in moving_mobs do
+	for mob, transform, v in world:query(Transform, Velocity):with(Mob):iter() do
 		local cf = transform.new
 		local p = cf.Position
 
@@ -65,24 +53,21 @@ end
 
 local throttle = interval(5)
 
-local function spawnMobs() 
+local function spawnMobs()
 	if throttle() then
 		local p = Vector3.new(0, 5, 0)
 		local cf = CFrame.new(p)
 		local v = 5
 
-		local e = world:entity()
+		local id = ref():set(Velocity, v):set(Transform, { new = cf }):add(Mob).id()
-		world:set(e, Velocity, v)
-		world:set(e, Transform, { new = cf })
-		world:add(e, Mob)
 
-		blink.SpawnMob.FireAll(e, cf, v)
+		blink.SpawnMob.FireAll(id, cf, v)
 	end
 end
 
-local scheduler = require(std.scheduler)
+return function(scheduler: std.Scheduler)
-
+	local phases = scheduler.phases
-scheduler.SYSTEM(spawnMobs)
+	local system_new = scheduler.systems.new
-scheduler.SYSTEM(mobsMove)
+	system_new(mobsMove, phases.Heartbeat)
-
+	system_new(spawnMobs, phases.Heartbeat)
-return 0
+end

demo/src/ServerScriptService/systems/players.luau

@@ -1,40 +1,43 @@
 local Players = game:GetService("Players")
 local ReplicatedStorage = game:GetService("ReplicatedStorage")
 
-local std = ReplicatedStorage.std
+local std = require(ReplicatedStorage.std)
-local ref = require(std.ref)
+local ref = std.ref
-local collect = require(std.collect)
+local collect = std.collect
 
-local cts = require(std.components)
+local cts = std.components
-local world = require(std.world)
 local Player = cts.Player
 local Character = cts.Character
 
+local playersAdded = collect(Players.PlayerAdded)
+local playersRemoved = collect(Players.PlayerRemoving)
+local world: std.World = std.world
+
 local conn = {}
 
-local function playersAdded(player: Player)
+local function players()
-	local e = ref(player.UserId)
+	for _, player in playersAdded do
-	world:set(e, Player, player)
+		world:set(std.world:entity(), cts.Transform)
-	local characterAdd = player.CharacterAdded
+
-	conn[e] = characterAdd:Connect(function(rig)
+		local e = ref(player.UserId):set(Player, player)
-		while rig.Parent ~= workspace do
+		local characterAdd = player.CharacterAdded
-			task.wait()
+		conn[e.id()] = characterAdd:Connect(function(rig)
-		end
+			while rig.Parent ~= workspace do
-		world:set(e, Character, rig)
+				task.wait()
-	end)
+			end
+			e:set(Character, rig)
+		end)
+	end
+
+	for _, player in playersRemoved do
+		local id = ref(player.UserId):clear().id()
+		conn[id]:Disconnect()
+		conn[id] = nil
+	end
 end
 
-local function playersRemoved(player: Player) 
+return function(scheduler: std.Scheduler)
-	local e = ref(player.UserId)
+	local phases = scheduler.phases
-	world:clear(e)
+	local system_new = scheduler.systems.new
-	local connection = conn[e]
+	system_new(players, phases.Heartbeat)
-	connection:Disconnect()
-	conn[e] = nil
 end
-
-local scheduler = require(std.scheduler)
-local phases = require(std.phases)
-scheduler.SYSTEM(playersAdded, phases.PlayerAdded)
-scheduler.SYSTEM(playersRemoved, phases.PlayerRemoved)
-
-return 0

demo/src/StarterPlayer/StarterPlayerScripts/systems/move.luau

@@ -1,22 +1,20 @@
 local ReplicatedStorage = game:GetService("ReplicatedStorage")
 local blink = require(ReplicatedStorage.net)
-local std = ReplicatedStorage.std
+local std = require(ReplicatedStorage.std)
-local world = require(std.world)
+local world = std.world
-local ref = require(std.ref)
+local ref = std.ref
 
-local cts = require(std.components)
+local cts = std.components
 
 local Model = cts.Model
 local Transform = cts.Transform
 
-local moving_models = world:query(Transform, Model):cached()
 local function move(dt: number)
-	for _, transform, model in moving_models do
+	for _, transform, model in world:query(Transform, Model):iter() do
 		local cf = transform.new
 		if cf ~= transform.old then
-			local part = model.PrimaryPart :: BasePart
+			local origo = model.PrimaryPart.CFrame
-			local origo = part.CFrame
+			model.PrimaryPart.CFrame = origo:Lerp(cf, 1)
-			part.CFrame = origo:Lerp(cf, 1)
 			transform.old = cf
 		end
 	end
@@ -24,8 +22,8 @@ end
 
 local function syncTransforms()
 	for _, id, cf in blink.UpdateTransform.Iter() do
-		local e = ref("server-" .. tostring(id))
+		local e = ref("server-" .. id)
-		local transform = world:get(e, Transform)
+		local transform = e:get(cts.Transform)
 		if not transform then
 			continue
 		end
@@ -33,9 +31,9 @@ local function syncTransforms()
 	end
 end
 
-local scheduler = require(std.scheduler)
+return function(scheduler: std.Scheduler)
-
+	local phases = scheduler.phases
-scheduler.SYSTEM(move)
+	local system_new = scheduler.systems.new
-scheduler.SYSTEM(syncTransforms)
+	system_new(move, phases.Heartbeat)
-
+	system_new(syncTransforms, phases.RenderStepped)
-return 0
+end

demo/src/StarterPlayer/StarterPlayerScripts/systems/syncMobs.luau

@@ -1,9 +1,9 @@
 local ReplicatedStorage = game:GetService("ReplicatedStorage")
 local blink = require(ReplicatedStorage.net)
-local std = ReplicatedStorage.std
+local std = require(ReplicatedStorage.std)
-local ref = require(std.ref)
+local ref = std.ref
-local world = require(std.world)
+local world = std.world
-local cts = require(std.components)
+local cts = std.components
 
 local function syncMobs()
 	for _, id, cf, vel in blink.SpawnMob.Iter() do
@@ -16,16 +16,16 @@ local function syncMobs()
 		part.Parent = model
 		model.Parent = workspace
 
-		local e = ref("server-" .. tostring(id))
+		ref("server-" .. id)
-		world:set(e, cts.Transform, { new = cf, old = cf })
+			:set(cts.Transform, { new = cf, old = cf })
-		world:set(e, cts.Velocity, vel)
+			:set(cts.Velocity, vel)
-		world:set(e, cts.Model, model)
+			:set(cts.Model, model)
-		world:add(e, cts.Mob)
+			:add(cts.Mob)
 	end
 end
 
-local scheduler = require(std.scheduler)
+return function(scheduler: std.Scheduler)
-scheduler.SYSTEM(syncMobs)
+	local phases = scheduler.phases
-
+	local system_new = scheduler.systems.new
-return 0
+	system_new(syncMobs, phases.RenderStepped)
-
+end

demo/src/StarterPlayer/StarterPlayerScripts/systems/test.luau

@@ -1,44 +0,0 @@
-local ReplicatedStorage = game:GetService("ReplicatedStorage")
-local std = ReplicatedStorage.std
-local world = require(std.world)
-
-local A = world:component()
-local B = world:component()
-local C = world:component()
-local D = world:component()
-
-local function flip() 
-    return math.random() >= 0.15
-end
-
-for i = 1, 2^8 do 
-    local e = world:entity()
-    if flip() then 
-        world:set(e, A, true)
-    end
-    if flip() then 
-        world:set(e, B, true)
-    end
-    if flip() then 
-        world:set(e, C, true)
-    end
-    if flip() then 
-        world:set(e, D, true)
-    end
-end
-
-local function uncached() 
-    for _ in world:query(A, B, C, D) do 
-    end
-end
-
-local q = world:query(A, B, C, D):cached()
-local function cached() 
-    for _ in q do 
-    end
-end
-
-local scheduler = require(std.scheduler)
-scheduler.SYSTEM(uncached)
-scheduler.SYSTEM(cached)
-return 0

jecs.d.ts

@@ -13,32 +13,24 @@ export type Tag = Entity<undefined>;
  * A pair of entities
  * P is the type of the predicate, O is the type of the object, and V is the type of the value (defaults to P)
  */
-export type Pair<P = Entity, O = Entity> = number & {
+export type Pair<P = undefined, O = undefined, V = P> = number & {
 	__jecs_pair_pred: P;
 	__jecs_pair_obj: O;
-	__jecs_pair_value: P extends Entity<undefined> 
+	__jecs_pair_value: V;
-		? O extends Entity<infer V> 
-			? V 
-			: never
-		: P extends Entity<infer V> ? V : never
 };
 
 /**
  * Either an Entity or a Pair
  */
-export type Id<T = unknown> = Entity<T> | Pair<Entity<T>, Entity<T>>;
+export type Id<T = unknown> = Entity<T> | Pair<unknown, unknown, T>;
-
-type InferComponent<E> = E extends Entity<infer T> 
-	? T 
-	: E extends Pair 
-		? E["__jecs_pair_value"] 
-		: never;
 
+type InferComponent<E> = E extends Id<infer T> ? T : never;
 type FlattenTuple<T extends any[]> = T extends [infer U] ? U : LuaTuple<T>;
 type Nullable<T extends unknown[]> = { [K in keyof T]: T[K] | undefined };
 type InferComponents<A extends Id[]> = {
 	[K in keyof A]: InferComponent<A[K]>;
 };
+type TupleForWorldGet = [Id] | [Id, Id] | [Id, Id, Id] | [Id, Id, Id, Id];
 
 type Iter<T extends unknown[]> = IterableFunction<LuaTuple<[Entity, ...T]>>;
 
@@ -144,7 +136,7 @@ export class World {
 	 * @param components Target Components
 	 * @returns Data associated with target components if it exists.
 	 */
-	get<T extends [Id] | [Id, Id] | [Id, Id, Id] | [Id, Id, Id, Id]>(id: Entity, ...components: T): FlattenTuple<Nullable<InferComponents<T>>>;
+	get<T extends TupleForWorldGet>(id: Entity, ...components: T): FlattenTuple<Nullable<InferComponents<T>>>;
 
 	/**
 	 * Returns whether the entity has the specified components.
@@ -184,7 +176,7 @@ export class World {
  * @param obj The second entity (object)
  * @returns The composite key (pair)
  */
-export function pair<P, O>(pred: Entity<P>, obj: Entity<O>): Pair<Entity<P>, Entity<O>>;
+export function pair<P, O, V = P>(pred: Entity<P>, obj: Entity<O>): Pair<P, O, V>;
 
 /**
  * Checks if the entity is a composite key (pair)
@@ -198,14 +190,14 @@ export function IS_PAIR(value: Id): value is Pair;
  * @param pair The pair to get the first entity from
  * @returns The first entity (predicate) of the pair
  */
-export function pair_first<P, O>(pair: Pair<P, O>): Entity<P>;
+export function pair_first<P, O, V = P>(pair: Pair<P, O, V>): Entity<P>;
 
 /**
  * Gets the second entity (object) of a pair
  * @param pair The pair to get the second entity from
  * @returns The second entity (object) of the pair
  */
-export function pair_second<P, O>(pair: Pair<P, O>): Entity<O>;
+export function pair_second<P, O, V = P>(pair: Pair<P, O, V>): Entity<O>;
 
 export const OnAdd: Entity<(e: Entity) => void>;
 export const OnRemove: Entity<(e: Entity) => void>;

jecs.luau

@@ -78,32 +78,30 @@ type EntityIndex = {
 
 local HI_COMPONENT_ID = _G.__JECS_HI_COMPONENT_ID or 256
 -- stylua: ignore start
-local EcsOnAdd =           HI_COMPONENT_ID +  1
+local EcsOnAdd =          HI_COMPONENT_ID +  1
-local EcsOnRemove =        HI_COMPONENT_ID +  2
+local EcsOnRemove =       HI_COMPONENT_ID +  2
-local EcsOnSet =           HI_COMPONENT_ID +  3
+local EcsOnSet =          HI_COMPONENT_ID +  3
-local EcsWildcard =        HI_COMPONENT_ID +  4
+local EcsWildcard =       HI_COMPONENT_ID +  4
-local EcsChildOf =         HI_COMPONENT_ID +  5
+local EcsChildOf =        HI_COMPONENT_ID +  5
-local EcsComponent =       HI_COMPONENT_ID +  6
+local EcsComponent =      HI_COMPONENT_ID +  6
-local EcsOnDelete =        HI_COMPONENT_ID +  7
+local EcsOnDelete =       HI_COMPONENT_ID +  7
-local EcsOnDeleteTarget =  HI_COMPONENT_ID +  8
+local EcsOnDeleteTarget = HI_COMPONENT_ID +  8
-local EcsDelete =          HI_COMPONENT_ID +  9
+local EcsDelete =         HI_COMPONENT_ID +  9
-local EcsRemove =          HI_COMPONENT_ID + 10
+local EcsRemove =         HI_COMPONENT_ID + 10
-local EcsName =            HI_COMPONENT_ID + 11
+local EcsName =           HI_COMPONENT_ID + 11
-local EcsArchetypeCreate = HI_COMPONENT_ID + 12
+local EcsRest =           HI_COMPONENT_ID + 12
-local EcsArchetypeDelete = HI_COMPONENT_ID + 13
-local EcsRest =            HI_COMPONENT_ID + 14
 
 local ECS_PAIR_FLAG =                       0x8
 local ECS_ID_FLAGS_MASK =                  0x10
 local ECS_ENTITY_MASK =     bit32.lshift(1, 24)
 local ECS_GENERATION_MASK = bit32.lshift(1, 16)
 
-local ECS_ID_DELETE =               0b0000_0001
+local ECS_ID_DELETE =              0b0000_0001
-local ECS_ID_IS_TAG =               0b0000_0010
+local ECS_ID_IS_TAG =              0b0000_0010
-local ECS_ID_HAS_ON_ADD =           0b0000_0100
+local ECS_ID_HAS_ON_ADD =          0b0000_0100
-local ECS_ID_HAS_ON_SET =           0b0000_1000
+local ECS_ID_HAS_ON_SET =          0b0000_1000
-local ECS_ID_HAS_ON_REMOVE =        0b0001_0000
+local ECS_ID_HAS_ON_REMOVE =       0b0001_0000
-local ECS_ID_MASK =                 0b0000_0000
+local ECS_ID_MASK =                0b0000_0000
 -- stylua: ignore end
 local NULL_ARRAY = table.freeze({}) :: Column
 
@@ -252,36 +250,6 @@ local function ecs_pair_second(world, e)
 	return entity_index_get_alive(world.entity_index, ECS_ENTITY_T_HI(e))
 end
 
-local function query_match(query, archetype: Archetype)
-	local records = archetype.records
-	local with = query.filter_with
-
-	for _, id in with do
-		if not records[id] then
-			return false
-		end
-	end
-
-	local without = query.filter_without
-	if without then
-		for _, id in without do
-			if records[id] then
-				return false
-			end
-		end
-	end
-
-	return true
-end
-
-local function find_observers(world: World, event, component): { Observer }?
-	local cache = world.observerable[event]
-	if not cache then
-		return nil
-	end
-	return cache[component] :: any
-end
-
 local function archetype_move(entity_index: EntityIndex, to: Archetype, dst_row: i24, from: Archetype, src_row: i24)
 	local src_columns = from.columns
 	local dst_columns = to.columns
@@ -581,20 +549,6 @@ local function archetype_create(world: World, id_types: { i24 }, ty, prev: i53?)
 	local columns = (table.create(length) :: any) :: { Column }
 
 	local records: { ArchetypeRecord } = {}
-
-	local archetype: Archetype = {
-		columns = columns,
-		entities = {},
-		id = archetype_id,
-		records = records,
-		type = ty,
-		types = id_types,
-
-		add = {},
-		remove = {},
-		refs = {} :: GraphEdge,
-	}
-
 	for i, componentId in id_types do
 		local idr = id_record_ensure(world, componentId)
 		archetype_append_to_records(idr, archetype_id, records, componentId, i)
@@ -618,17 +572,18 @@ local function archetype_create(world: World, id_types: { i24 }, ty, prev: i53?)
 		end
 	end
 
-	for _, id in id_types do
+	local archetype: Archetype = {
-		local observer_list = find_observers(world, EcsArchetypeCreate, id)
+		columns = columns,
-		if not observer_list then
+		entities = {},
-			continue
+		id = archetype_id,
-		end
+		records = records,
-		for _, observer in observer_list do
+		type = ty,
-			if query_match(observer.query, archetype) then
+		types = id_types,
-				observer.callback(archetype)
+
-			end
+		add = {},
-		end
+		remove = {},
-	end
+		refs = {} :: GraphEdge,
+	}
 
 	world.archetypeIndex[ty] = archetype
 	world.archetypes[archetype_id] = archetype
@@ -671,13 +626,13 @@ local function find_insert(id_types: { i53 }, toAdd: i53): number
 end
 
 local function find_archetype_with(world: World, node: Archetype, id: i53): Archetype
-	local id_types = node.types
+	local types = node.types
 	-- Component IDs are added incrementally, so inserting and sorting
 	-- them each time would be expensive. Instead this insertion sort can find the insertion
 	-- point in the types array.
 
 	local dst = table.clone(node.types) :: { i53 }
-	local at = find_insert(id_types, id)
+	local at = find_insert(types, id)
 	if at == -1 then
 		-- If it finds a duplicate, it just means it is the same archetype so it can return it
 		-- directly instead of needing to hash types for a lookup to the archetype.
@@ -689,13 +644,13 @@ local function find_archetype_with(world: World, node: Archetype, id: i53): Arch
 end
 
 local function find_archetype_without(world: World, node: Archetype, id: i53): Archetype
-	local id_types = node.types
+	local types = node.types
-	local at = table.find(id_types, id)
+	local at = table.find(types, id)
 	if at == nil then
 		return node
 	end
 
-	local dst = table.clone(id_types)
+	local dst = table.clone(types)
 	table.remove(dst, at)
 
 	return archetype_ensure(world, dst)
@@ -1051,18 +1006,6 @@ local function archetype_destroy(world: World, archetype: Archetype)
 	world.archetypeIndex[archetype.type] = nil :: any
 	local records = archetype.records
 
-	for id in records do
-		local observer_list = find_observers(world, EcsArchetypeDelete, id)
-		if not observer_list then
-			continue
-		end
-		for _, observer in observer_list do
-			if query_match(observer.query, archetype) then
-				observer.callback(archetype)
-			end
-		end
-	end
-
 	for id in records do
 		local idr = component_index[id]
 		idr.cache[archetype_id] = nil :: any
@@ -1121,30 +1064,23 @@ do
 		local idr = component_index[delete]
 
 		if idr then
+			local children = {}
+			for archetype_id in idr.cache do
+				local idr_archetype = archetypes[archetype_id]
+
+				for i, child in idr_archetype.entities do
+					table.insert(children, child)
+				end
+			end
 			local flags = idr.flags
 			if bit32.band(flags, ECS_ID_DELETE) ~= 0 then
-				for archetype_id in idr.cache do
+				for _, child in children do
-					local idr_archetype = archetypes[archetype_id]
+					-- Cascade deletion to children
-
+					world_delete(world, child)
-					local entities = idr_archetype.entities
-					local n = #entities
-					for i = n, 1, -1 do
-						world_delete(world, entities[i])
-					end
 				end
 			else
-				for archetype_id in idr.cache do
+				for _, child in children do
-					local idr_archetype = archetypes[archetype_id]
+					world_remove(world, child, delete)
-					local entities = idr_archetype.entities
-					local n = #entities
-					for i = n, 1, -1 do
-						world_remove(world, entities[i], delete)
-					end
-				end
-
-				for archetype_id in idr.cache do
-					local idr_archetype = archetypes[archetype_id]
-					archetype_destroy(world, idr_archetype)
 				end
 			end
 		end
@@ -1231,7 +1167,7 @@ local EMPTY_QUERY = {
 
 setmetatable(EMPTY_QUERY, EMPTY_QUERY)
 
-local function query_iter_init(query: QueryInner): () -> (number, ...any)
+local function query_iter_init(query): () -> (number, ...any)
 	local world_query_iter_next
 
 	local compatible_archetypes = query.compatible_archetypes
@@ -1310,7 +1246,7 @@ local function query_iter_init(query: QueryInner): () -> (number, ...any)
 				i = #entities
 				entityId = entities[i]
 				columns = archetype.columns
-				records = archetype.records
+				local records = archetype.records
 				a = columns[records[A].column]
 			end
 
@@ -1333,7 +1269,7 @@ local function query_iter_init(query: QueryInner): () -> (number, ...any)
 				i = #entities
 				entityId = entities[i]
 				columns = archetype.columns
-				records = archetype.records
+				local records = archetype.records
 				a = columns[records[A].column]
 				b = columns[records[B].column]
 			end
@@ -1357,7 +1293,7 @@ local function query_iter_init(query: QueryInner): () -> (number, ...any)
 				i = #entities
 				entityId = entities[i]
 				columns = archetype.columns
-				records = archetype.records
+				local records = archetype.records
 				a = columns[records[A].column]
 				b = columns[records[B].column]
 				c = columns[records[C].column]
@@ -1382,7 +1318,7 @@ local function query_iter_init(query: QueryInner): () -> (number, ...any)
 				i = #entities
 				entityId = entities[i]
 				columns = archetype.columns
-				records = archetype.records
+				local records = archetype.records
 				a = columns[records[A].column]
 				b = columns[records[B].column]
 				c = columns[records[C].column]
@@ -1409,7 +1345,7 @@ local function query_iter_init(query: QueryInner): () -> (number, ...any)
 				i = #entities
 				entityId = entities[i]
 				columns = archetype.columns
-				records = archetype.records
+				local records = archetype.records
 
 				if not F then
 					a = columns[records[A].column]
@@ -1478,64 +1414,65 @@ local function query_iter(query): () -> (number, ...any)
 	return query_next
 end
 
-local function query_without(query: QueryInner, ...: i53)
+local function query_without(query: { compatible_archetypes: { Archetype } }, ...)
-	local without = { ... }
-	query.filter_without = without
 	local compatible_archetypes = query.compatible_archetypes
+	local N = select("#", ...)
 	for i = #compatible_archetypes, 1, -1 do
 		local archetype = compatible_archetypes[i]
 		local records = archetype.records
-		local matches = true
+		local shouldRemove = false
 
-		for _, id in without do
+		for j = 1, N do
+			local id = select(j, ...)
 			if records[id] then
-				matches = false
+				shouldRemove = true
 				break
 			end
 		end
 
-		if matches then
+		if shouldRemove then
-			continue
+			local last = #compatible_archetypes
+			if last ~= i then
+				compatible_archetypes[i] = compatible_archetypes[last]
+			end
+			compatible_archetypes[last] = nil :: any
 		end
+	end
 
-		local last = #compatible_archetypes
+	if #compatible_archetypes == 0 then
-		if last ~= i then
+		return EMPTY_QUERY
-			compatible_archetypes[i] = compatible_archetypes[last]
-		end
-		compatible_archetypes[last] = nil :: any
 	end
 
 	return query :: any
 end
 
-local function query_with(query: QueryInner, ...: i53)
+local function query_with(query: { compatible_archetypes: { Archetype } }, ...)
 	local compatible_archetypes = query.compatible_archetypes
-	local with = { ... }
+	local N = select("#", ...)
-	query.filter_with = with
-
 	for i = #compatible_archetypes, 1, -1 do
 		local archetype = compatible_archetypes[i]
 		local records = archetype.records
-		local matches = true
+		local shouldRemove = false
 
-		for _, id in with do
+		for j = 1, N do
+			local id = select(j, ...)
 			if not records[id] then
-				matches = false
+				shouldRemove = true
 				break
 			end
 		end
 
-		if matches then
+		if shouldRemove then
-			continue
+			local last = #compatible_archetypes
+			if last ~= i then
+				compatible_archetypes[i] = compatible_archetypes[last]
+			end
+			compatible_archetypes[last] = nil :: any
 		end
-
-		local last = #compatible_archetypes
-		if last ~= i then
-			compatible_archetypes[i] = compatible_archetypes[last]
-		end
-		compatible_archetypes[last] = nil :: any
 	end
-
+	if #compatible_archetypes == 0 then
+		return EMPTY_QUERY
+	end
 	return query :: any
 end
 
@@ -1546,311 +1483,6 @@ local function query_archetypes(query)
 	return query.compatible_archetypes
 end
 
-local function query_cached(query: QueryInner)
-	local archetypes = query.compatible_archetypes
-	local world = query.world :: World
-	-- Only need one observer for EcsArchetypeCreate and EcsArchetypeDelete respectively
-	-- because the event will be emitted for all components of that Archetype.
-	local first = query.ids[1]
-	local observerable = world.observerable
-	local on_create_action = observerable[EcsArchetypeCreate]
-	if not on_create_action then
-		on_create_action = {}
-		observerable[EcsArchetypeCreate] = on_create_action
-	end
-	local query_cache_on_create = on_create_action[first]
-	if not query_cache_on_create then
-		query_cache_on_create = {}
-		on_create_action[first] = query_cache_on_create
-	end
-
-	local on_delete_action = observerable[EcsArchetypeDelete]
-	if not on_delete_action then
-		on_delete_action = {}
-		observerable[EcsArchetypeDelete] = on_delete_action
-	end
-	local query_cache_on_delete = on_delete_action[first]
-	if not query_cache_on_delete then
-		query_cache_on_delete = {}
-		on_delete_action[first] = query_cache_on_delete
-	end
-
-	local function on_create_callback(archetype)
-		table.insert(archetypes, archetype)
-	end
-
-	local function on_delete_callback(archetype)
-		local i = table.find(archetypes, archetype)  :: number
-		local n = #archetypes
-		archetypes[i] = archetypes[n]
-		archetypes[n] = nil
-	end
-
-	local with = query.filter_with
-	local ids = query.ids
-	if with then
-		table.move(ids, 1, #ids, #with, with)
-	else
-		query.filter_with = ids
-	end
-
-	local observer_for_create = { query = query, callback = on_create_callback }
-	local observer_for_delete = { query = query, callback = on_delete_callback }
-
-	table.insert(query_cache_on_create, observer_for_create)
-	table.insert(query_cache_on_delete, observer_for_delete)
-
-	local compatible_archetypes = query.compatible_archetypes
-	local lastArchetype = 1
-
-	local A, B, C, D, E, F, G, H, I = unpack(ids)
-	local a: Column, b: Column, c: Column, d: Column
-	local e: Column, f: Column, g: Column, h: Column
-
-	local world_query_iter_next
-	local columns: { Column }
-	local entities: { i53 }
-	local i: number
-	local archetype: Archetype
-	local records: { ArchetypeRecord }
-
-	if not B then
-		function world_query_iter_next(): any
-			local entityId = entities[i]
-			while entityId == nil do
-				lastArchetype += 1
-				archetype = compatible_archetypes[lastArchetype]
-				if not archetype then
-					return nil
-				end
-
-				entities = archetype.entities
-				i = #entities
-				entityId = entities[i]
-				columns = archetype.columns
-				records = archetype.records
-				a = columns[records[A].column]
-			end
-
-			local row = i
-			i -= 1
-
-			return entityId, a[row]
-		end
-	elseif not C then
-		function world_query_iter_next(): any
-			local entityId = entities[i]
-			while entityId == nil do
-				lastArchetype += 1
-				archetype = compatible_archetypes[lastArchetype]
-				if not archetype then
-					return nil
-				end
-
-				entities = archetype.entities
-				i = #entities
-				entityId = entities[i]
-				columns = archetype.columns
-				local records = archetype.records
-				a = columns[records[A].column]
-				b = columns[records[B].column]
-			end
-
-			local row = i
-			i -= 1
-
-			return entityId, a[row], b[row]
-		end
-	elseif not D then
-		function world_query_iter_next(): any
-			local entityId = entities[i]
-			while entityId == nil do
-				lastArchetype += 1
-				archetype = compatible_archetypes[lastArchetype]
-				if not archetype then
-					return nil
-				end
-
-				entities = archetype.entities
-				i = #entities
-				entityId = entities[i]
-				columns = archetype.columns
-				local records = archetype.records
-				a = columns[records[A].column]
-				b = columns[records[B].column]
-				c = columns[records[C].column]
-			end
-
-			local row = i
-			i -= 1
-
-			return entityId, a[row], b[row], c[row]
-		end
-	elseif not E then
-		function world_query_iter_next(): any
-			local entityId = entities[i]
-			while entityId == nil do
-				lastArchetype += 1
-				archetype = compatible_archetypes[lastArchetype]
-				if not archetype then
-					return nil
-				end
-
-				entities = archetype.entities
-				i = #entities
-				entityId = entities[i]
-				columns = archetype.columns
-				local records = archetype.records
-				a = columns[records[A].column]
-				b = columns[records[B].column]
-				c = columns[records[C].column]
-				d = columns[records[D].column]
-			end
-
-			local row = i
-			i -= 1
-
-			return entityId, a[row], b[row], c[row], d[row]
-		end
-	else
-		local queryOutput = {}
-		function world_query_iter_next(): any
-			local entityId = entities[i]
-			while entityId == nil do
-				lastArchetype += 1
-				archetype = compatible_archetypes[lastArchetype]
-				if not archetype then
-					return nil
-				end
-
-				entities = archetype.entities
-				i = #entities
-				entityId = entities[i]
-				columns = archetype.columns
-				local records = archetype.records
-
-				if not F then
-					a = columns[records[A].column]
-					b = columns[records[B].column]
-					c = columns[records[C].column]
-					d = columns[records[D].column]
-					e = columns[records[E].column]
-				elseif not G then
-					a = columns[records[A].column]
-					b = columns[records[B].column]
-					c = columns[records[C].column]
-					d = columns[records[D].column]
-					e = columns[records[E].column]
-					f = columns[records[F].column]
-				elseif not H then
-					a = columns[records[A].column]
-					b = columns[records[B].column]
-					c = columns[records[C].column]
-					d = columns[records[D].column]
-					e = columns[records[E].column]
-					f = columns[records[F].column]
-					g = columns[records[G].column]
-				elseif not I then
-					a = columns[records[A].column]
-					b = columns[records[B].column]
-					c = columns[records[C].column]
-					d = columns[records[D].column]
-					e = columns[records[E].column]
-					f = columns[records[F].column]
-					g = columns[records[G].column]
-					h = columns[records[H].column]
-				end
-			end
-
-			local row = i
-			i -= 1
-
-			if not F then
-				return entityId, a[row], b[row], c[row], d[row], e[row]
-			elseif not G then
-				return entityId, a[row], b[row], c[row], d[row], e[row], f[row]
-			elseif not H then
-				return entityId, a[row], b[row], c[row], d[row], e[row], f[row], g[row]
-			elseif not I then
-				return entityId, a[row], b[row], c[row], d[row], e[row], f[row], g[row], h[row]
-			end
-
-			local records = archetype.records
-			for j, id in ids do
-				queryOutput[j] = columns[records[id].column][row]
-			end
-
-			return entityId, unpack(queryOutput)
-		end
-	end
-
-	local function cached_query_iter()
-		lastArchetype = 1
-		archetype = compatible_archetypes[lastArchetype]
-		if not archetype then
-			return NOOP
-		end
-		entities = archetype.entities
-		i = #entities
-		records = archetype.records
-		columns = archetype.columns
-		if not B then
-			a = columns[records[A].column]
-		elseif not C then
-			a = columns[records[A].column]
-			b = columns[records[B].column]
-		elseif not D then
-			a = columns[records[A].column]
-			b = columns[records[B].column]
-			c = columns[records[C].column]
-		elseif not E then
-			a = columns[records[A].column]
-			b = columns[records[B].column]
-			c = columns[records[C].column]
-			d = columns[records[D].column]
-		elseif not F then
-			a = columns[records[A].column]
-			b = columns[records[B].column]
-			c = columns[records[C].column]
-			d = columns[records[D].column]
-			e = columns[records[E].column]
-		elseif not G then
-			a = columns[records[A].column]
-			b = columns[records[B].column]
-			c = columns[records[C].column]
-			d = columns[records[D].column]
-			e = columns[records[E].column]
-			f = columns[records[F].column]
-		elseif not H then
-			a = columns[records[A].column]
-			b = columns[records[B].column]
-			c = columns[records[C].column]
-			d = columns[records[D].column]
-			e = columns[records[E].column]
-			f = columns[records[F].column]
-			g = columns[records[G].column]
-		elseif not I then
-			a = columns[records[A].column]
-			b = columns[records[B].column]
-			c = columns[records[C].column]
-			d = columns[records[D].column]
-			e = columns[records[E].column]
-			f = columns[records[F].column]
-			g = columns[records[G].column]
-			h = columns[records[H].column]
-		end
-
-		return world_query_iter_next
-	end
-
-	local cached_query = query :: any
-	cached_query.archetypes = query_archetypes
-	cached_query.__iter = cached_query_iter
-	cached_query.iter = cached_query_iter
-	setmetatable(cached_query, cached_query)
-	return cached_query
-end
-
 local Query = {}
 Query.__index = Query
 Query.__iter = query_iter
@@ -1858,7 +1490,6 @@ Query.iter = query_iter_init
 Query.without = query_without
 Query.with = query_with
 Query.archetypes = query_archetypes
-Query.cached = query_cached
 
 local function world_query(world: World, ...)
 	local compatible_archetypes = {}
@@ -1871,16 +1502,10 @@ local function world_query(world: World, ...)
 	local idr: IdRecord?
 	local componentIndex = world.componentIndex
 
-	local q = setmetatable({
-		ids = ids,
-		compatible_archetypes = compatible_archetypes,
-		world = world,
-	}, Query)
-
 	for _, id in ids do
 		local map = componentIndex[id]
 		if not map then
-			return q
+			return EMPTY_QUERY
 		end
 
 		if idr == nil or map.size < idr.size then
@@ -1889,7 +1514,7 @@ local function world_query(world: World, ...)
 	end
 
 	if not idr then
-		return q
+		return EMPTY_QUERY
 	end
 
 	for archetype_id in idr.cache do
@@ -1917,6 +1542,15 @@ local function world_query(world: World, ...)
 		compatible_archetypes[length] = compatibleArchetype
 	end
 
+	if length == 0 then
+		return EMPTY_QUERY
+	end
+
+	local q = setmetatable({
+		compatible_archetypes = compatible_archetypes,
+		ids = ids,
+	}, Query) :: any
+
 	return q
 end
 
@@ -2102,7 +1736,6 @@ function World.new()
 		nextComponentId = 0 :: number,
 		nextEntityId = 0 :: number,
 		ROOT_ARCHETYPE = (nil :: any) :: Archetype,
-		observerable = {},
 	}, World) :: any
 
 	self.ROOT_ARCHETYPE = archetype_create(self, {}, "")
@@ -2148,7 +1781,7 @@ type function ecs_entity_t(entity)
 	return entity:components()[2]:readproperty(types.singleton("__T"))
 end
 
-type function Pair(first, second)
+export type function Pair(first, second)
     local thing = first:components()[2]
 
 	if thing:readproperty(types.singleton("__T")):is("nil") then
@@ -2164,38 +1797,15 @@ export type Entity<T = unknown> = number & { __T: T }
 
 type Iter<T...> = (query: Query<T...>) -> () -> (Entity, T...)
 
-export type Query<T...> = typeof(setmetatable({}, {
+type Query<T...> = typeof(setmetatable({}, {
 	__iter = (nil :: any) :: Iter<T...>,
 })) & {
 	iter: Iter<T...>,
-	with: (self: Query<T...>, ...Id) -> Query<T...>,
+	with: (self: Query<T...>, ...i53) -> Query<T...>,
-	without: (self: Query<T...>, ...Id) -> Query<T...>,
+	without: (self: Query<T...>, ...i53) -> Query<T...>,
 	archetypes: (self: Query<T...>) -> { Archetype },
-	cached: (self: Query<T...>) -> Query<T...>,
 }
 
-type QueryInner = {
-	compatible_archetypes: { Archetype },
-	filter_with: { i53 }?,
-	filter_without: { i53 }?,
-	ids: { i53 },
-	world: {}, -- Downcasted to be serializable by the analyzer
-	next: () -> Item<any>
-}
-
-type Observer = {
- 	callback: (archetype: Archetype) -> (),
-   	query: QueryInner,
-}
-
-type function ecs_partial_t(ty)
-	local output = types.newtable()
-	for k, v in ty:properties() do
-		output:setproperty(k, types.unionof(v.write, types.singleton(nil)))
-	end
-	return output
-end
-
 export type World = {
 	archetypeIndex: { [string]: Archetype },
 	archetypes: Archetypes,
@@ -2206,8 +1816,6 @@ export type World = {
 	nextComponentId: number,
 	nextEntityId: number,
 	nextArchetypeId: number,
-
-	observerable: { [i53]: { [i53]: { { query: Query<i53> } } } },
 } & {
 	--- Creates a new entity
 	entity: (self: World) -> Entity,

package.json

@@ -1,6 +1,6 @@
 {
 	"name": "@rbxts/jecs",
-	"version": "0.5.0",
+	"version": "0.4.1-rc.0",
 	"description": "Stupidly fast Entity Component System",
 	"main": "jecs.luau",
 	"repository": {

test/tests.luau

@@ -63,10 +63,6 @@ local function debug_world_inspect(world: World)
 	}
 end
 
-local function name(world, e)
-	return world:get(e, jecs.Name)
-end
-
 TEST("archetype", function()
 	local archetype_append_to_records = jecs.archetype_append_to_records
 	local id_record_ensure = jecs.id_record_ensure
@@ -363,39 +359,6 @@ TEST("world:add()", function()
 end)
 
 TEST("world:query()", function()
-	do CASE "cached"
-		local world = world_new()
-		local Foo = world:component()
-		local Bar = world:component()
-		local Baz = world:component()
-		local e = world:entity()
-		local q = world:query(Foo, Bar):without(Baz):cached()
-		world:set(e, Foo, true)
-		world:set(e, Bar, false)
-		local i = 0
-
-		for _, e in q:iter() do
-			i=1
-		end
-		CHECK(i == 1)
-		for _, e in q:iter() do
-			i=2
-		end
-		CHECK(i == 2)
-		for _, e in q do
-			i=3
-		end
-		CHECK(i == 3)
-		for _, e in q do
-			i=4
-		end
-		CHECK(i == 4)
-
-		CHECK(#q:archetypes() == 1)
-		CHECK(not table.find(q:archetypes(), world.archetypes[table.concat({Foo, Bar, Baz}, "_")]))
-		world:delete(Foo)
-		CHECK(#q:archetypes() == 0)
-	end
 	do CASE("multiple iter")
 		local world = jecs.World.new()
 		local A = world:component()
@@ -851,6 +814,40 @@ TEST("world:query()", function()
 		CHECK(withoutCount == 0)
 	end
 
+	do
+		CASE("Empty Query")
+		do
+			local world = jecs.World.new()
+			local A = world:component()
+			local B = world:component()
+
+			local e1 = world:entity()
+			world:add(e1, A)
+
+			local query = world:query(B)
+			CHECK(query:without() == query)
+			CHECK(query:with() == query)
+			-- They always return the same EMPTY_LIST
+			CHECK(query:archetypes() == world:query(B):archetypes())
+		end
+
+		do
+			local world = jecs.World.new()
+			local A = world:component()
+			local B = world:component()
+
+			local e1 = world:entity()
+			world:add(e1, A)
+
+			local count = 0
+			for id in world:query(B) do
+				count += 1
+			end
+
+			CHECK(count == 0)
+		end
+	end
+
 	do
 		CASE("without")
 		do

wally.toml

@@ -1,6 +1,6 @@
 [package]
 name = "ukendio/jecs"
-version = "0.5.0"
+version = "0.4.1-rc.0"
 registry = "https://github.com/UpliftGames/wally-index"
 realm = "shared"
 license = "MIT"