Fix line endings (#280)

* Allow any amount of undefined in bulk_insert

* Also handle unknown

addons/ob.luau

@@ -10,29 +10,28 @@ type Entity<T> = jecs.Entity<T>
 
 export type Iter<T...> = (Observer<T...>) -> () -> (jecs.Entity, T...)
 
-export type Observer<T...> = typeof(setmetatable(
-	{} :: {
-		iter: Iter<T...>,
-		entities: { Entity<nil> },
-		disconnect: (Observer<T...>) -> ()
-	},
-	{} :: {
-		__iter: Iter<T...>,
+export type Observer<T...> = {
+	disconnect: (Observer<T...>) -> (),
+}
+
+export type Monitor<T...> = {
+	disconnect: (Observer<T...>) -> (),
+	added: ((jecs.Entity) -> ()) -> (),
+	removed: ((jecs.Entity) -> ()) -> ()
 }
-))
 
 local function observers_new<T...>(
 	query: Query<T...>,
-	callback: ((Entity<nil>, Id<any>, value: any?) -> ())?
+	callback: ((Entity<nil>) -> ())
 ): Observer<T...>
-
 	query:cached()
 
+
 	local world = (query :: Query<T...> & { world: World }).world
 	callback = callback
 
 	local archetypes = {}
-	local terms = query.ids
+	local terms = query.filter_with :: { jecs.Id }
 	local first = terms[1]
 
 	local observers_on_create = world.observable[jecs.ArchetypeCreate][first]
@@ -47,8 +46,10 @@ local function observers_new<T...>(
 	end
 
 	local entity_index = world.entity_index :: any
-	local i = 0
-	local entities = {}
+
+	for _, archetype in query:archetypes() do
+		archetypes[archetype.id] = true
+	end
 
 	local function emplaced<T, a>(
 		entity: jecs.Entity<T>,
@@ -60,20 +61,59 @@ local function observers_new<T...>(
 		local archetype = r.archetype
 
 		if archetypes[archetype.id] then
-			i += 1
-			entities[i] = entity
-			if callback ~= nil then
-				callback(entity, id, value)
-			end
+			callback(entity)
 		end
 	end
 
+	local cleanup = {}
+
 	for _, term in terms do
 		if jecs.IS_PAIR(term) then
 			term = jecs.ECS_PAIR_FIRST(term)
 		end
-		world:added(term, emplaced)
-		world:changed(term, emplaced)
+		local onadded = world:added(term, emplaced)
+		local onchanged = world:changed(term, emplaced)
+		table.insert(cleanup, onadded)
+		table.insert(cleanup, onchanged)
+ 	end
+
+	local without = query.filter_without
+   	if without then
+		for _, term in without do
+			if jecs.IS_PAIR(term) then
+				local rel = jecs.ECS_PAIR_FIRST(term)
+				local tgt = jecs.ECS_PAIR_SECOND(term)
+				local wc = tgt == jecs.w
+				local onremoved = world:removed(rel, function(entity, id)
+					if not wc and id ~= term then
+						return
+					end
+					local r = jecs.record(world, entity)
+					local archetype = r.archetype
+					if archetype then
+						local dst = jecs.archetype_traverse_remove(world, id, archetype)
+						if archetypes[dst.id] then
+							callback(entity)
+						end
+					end
+				end)
+
+				table.insert(cleanup, onremoved)
+			else
+				local onremoved = world:removed(term, function(entity, id)
+					local r = jecs.record(world, entity)
+					local archetype = r.archetype
+					if archetype then
+						local dst = jecs.archetype_traverse_remove(world, id, archetype)
+						if archetypes[dst.id] then
+							callback(entity)
+						end
+					end
+				end)
+
+				table.insert(cleanup, onremoved)
+			end
+		end
 	end
 
  	local function disconnect()
@@ -86,44 +126,28 @@ local function observers_new<T...>(
 	      	observers_on_delete,
 	       	observer_on_delete
        	))
-   	end
 
-    local function iter()
-  		local row = i
-  		return function()
- 			if row == 0 then
-     			i = 0
-      			table.clear(entities)
-      		end
-           	local entity = entities[row]
-           	row -= 1
-           	return entity
+		table.clear(archetypes)
+
+		for _, disconnect in cleanup do
+			disconnect()
 		end
    	end
 
 	local observer = {
   		disconnect = disconnect,
-     	entities = entities,
-     	__iter = iter,
-      	iter = iter
    	}
 
-    setmetatable(observer, observer)
-
     return (observer :: any) :: Observer<T...>
 end
 
-local function monitors_new<T...>(
-	query: Query<T...>,
-	callback: ((Entity<nil>, Id<any>, value: any?) -> ())?
-): Observer<T...>
-
+local function monitors_new<T...>(query: Query<T...>): Monitor<T...>
 	query:cached()
 
 	local world = (query :: Query<T...> & { world: World }).world
 
 	local archetypes = {}
-	local terms = query.ids
+	local terms = query.filter_with :: { jecs.Id<any> }
 	local first = terms[1]
 
 	local observers_on_create = world.observable[jecs.ArchetypeCreate][first]
@@ -136,42 +160,129 @@ local function monitors_new<T...>(
 	observer_on_delete.callback = function(archetype)
 		archetypes[archetype.id] = nil
 	end
+
+	for _, archetype in query:archetypes() do
+		archetypes[archetype.id] = true
+	end
 	local entity_index = world.entity_index :: any
-	local i = 0
-	local entities = {}
+
+	local callback_added: ((jecs.Entity) -> ())?
+	local callback_removed: ((jecs.Entity) -> ())?
 
 	local function emplaced<T, a>(
 		entity: jecs.Entity<T>,
 		id: jecs.Id<a>,
 		value: a?
 	)
+		if callback_added == nil then
+			return
+		end
+
 		local r = jecs.entity_index_try_get_fast(
 			entity_index, entity :: any) :: jecs.Record
 
 		local archetype = r.archetype
 
 		if archetypes[archetype.id] then
-			i += 1
-			entities[i] = entity
-			if callback ~= nil then
-				callback(entity, jecs.OnAdd)
-			end
+			callback_added(entity)
 		end
 	end
 
 	local function removed(entity: jecs.Entity, component: jecs.Id)
-		local EcsOnRemove = jecs.OnRemove :: jecs.Id
-		if callback ~= nil then
-			callback(entity, EcsOnRemove)
+		if callback_removed == nil then
+			return
 		end
+		local r = jecs.record(world, entity)
+		if not archetypes[r.archetype.id] then
+			return
 		end
+		callback_removed(entity)
+	end
+
+	local cleanup = {}
 
 	for _, term in terms do
 		if jecs.IS_PAIR(term) then
 			term = jecs.ECS_PAIR_FIRST(term)
 		end
-		world:added(term, emplaced)
-		world:removed(term, removed)
+		local onadded = world:added(term, emplaced)
+		local onremoved = world:removed(term, removed)
+		table.insert(cleanup, onadded)
+		table.insert(cleanup, onremoved)
+ 	end
+
+  	local without = query.filter_without
+   	if without then
+	   	for _, term in without do
+			if jecs.IS_PAIR(term) then
+				local rel = jecs.ECS_PAIR_FIRST(term)
+				local tgt = jecs.ECS_PAIR_SECOND(term)
+				local wc = tgt == jecs.w
+				local onadded = world:added(rel, function(entity, id)
+					if callback_removed == nil then
+						return
+					end
+					if not wc and id ~= term then
+						return
+					end
+					local r = jecs.record(world, entity)
+					local archetype = r.archetype
+					if archetype then
+						local dst = jecs.archetype_traverse_remove(world, id, archetype)
+						if archetypes[dst.id] then
+							callback_removed(entity)
+						end
+					end
+				end)
+				local onremoved = world:removed(rel, function(entity, id)
+					if callback_added == nil then
+						return
+					end
+					if not wc and id ~= term then
+						return
+					end
+					local r = jecs.record(world, entity)
+					local archetype = r.archetype
+					if archetype then
+						local dst = jecs.archetype_traverse_remove(world, id, archetype)
+						if archetypes[dst.id] then
+							callback_added(entity)
+						end
+					end
+				end)
+				table.insert(cleanup, onadded)
+				table.insert(cleanup, onremoved)
+			else
+				local onadded = world:added(term, function(entity, id)
+					if callback_removed == nil then
+						return
+					end
+					local r = jecs.record(world, entity)
+					local archetype = r.archetype
+					if archetype then
+						local dst = jecs.archetype_traverse_remove(world, id, archetype)
+						if archetypes[dst.id] then
+							callback_removed(entity)
+						end
+					end
+				end)
+				local onremoved = world:removed(term, function(entity, id)
+					if callback_added == nil then
+						return
+					end
+					local r = jecs.record(world, entity)
+					local archetype = r.archetype
+					if archetype then
+						local dst = jecs.archetype_traverse_remove(world, id, archetype)
+						if archetypes[dst.id] then
+							callback_added(entity)
+						end
+					end
+				end)
+				table.insert(cleanup, onadded)
+				table.insert(cleanup, onremoved)
+			end
+    	end
     end
 
  	local function disconnect()
@@ -184,31 +295,29 @@ local function monitors_new<T...>(
 	      	observers_on_delete,
 	       	observer_on_delete
        	))
+
+		table.clear(archetypes)
+
+		for _, disconnect in cleanup do
+			disconnect()
+		end
    	end
 
-    local function iter()
-  		local row = i
-  		return function()
- 			if row == 0 then
-     			i = 0
-     			table.clear(entities)
-      		end
-           	local entity = entities[row]
-           	row -= 1
-           	return entity
+    local function monitor_added(callback)
+		callback_added = callback
     end
+
+    local function monitor_removed(callback)
+    	callback_removed = callback
     end
 
 	local observer = {
   		disconnect = disconnect,
-	   	entities = entities,
-	   	__iter = iter,
-       	iter = iter
+    	added = monitor_added,
+     	removed = monitor_removed
    	}
 
-    setmetatable(observer, observer)
-
-    return (observer :: any) :: Observer<T...>
+    return (observer :: any) :: Monitor<T...>
 end
 
 return {

benches/general.luau

@@ -199,6 +199,7 @@ do
 			end
 
 			local q = world:query(A, B, C, D)
+			q:archetypes()
 			START()
 			for id in q do
 			end

benches/query.luau

@@ -11,15 +11,22 @@ end
 local jecs = require("@jecs")
 local mirror = require("@mirror")
 
-type i53 = number
-
 do
 	TITLE(testkit.color.white_underline("Jecs query"))
-	local ecs = jecs.world()
+	local ecs = jecs.world() :: jecs.World
 	do
 		TITLE("one component in common")
 
-		local function view_bench(world: jecs.World, A: i53, B: i53, C: i53, D: i53, E: i53, F: i53, G: i53, H: i53)
+		local function view_bench(world: jecs.World,
+			A: jecs.Id,
+			B: jecs.Id,
+			C: jecs.Id,
+			D: jecs.Id,
+			E: jecs.Id,
+			F: jecs.Id,
+			G: jecs.Id,
+			H: jecs.Id
+		)
 			BENCH("1 component", function()
 				for _ in world:query(A) do
 				end
@@ -131,11 +138,21 @@ end
 
 do
 	TITLE(testkit.color.white_underline("Mirror query"))
-	local ecs = mirror.World.new()
+	local ecs = mirror.World.new() :: jecs.World
 	do
 		TITLE("one component in common")
 
-		local function view_bench(world: jecs.World, A: i53, B: i53, C: i53, D: i53, E: i53, F: i53, G: i53, H: i53)
+		local function view_bench(
+			world: mirror.World,
+			A: jecs.Id,
+			B: jecs.Id,
+			C: jecs.Id,
+			D: jecs.Id,
+			E: jecs.Id,
+			F: jecs.Id,
+			G: jecs.Id,
+			H: jecs.Id
+		)
 			BENCH("1 component", function()
 				for _ in world:query(A) do
 				end

benches/visual/query.bench.luau

@@ -2,33 +2,12 @@
 --!native
 
 local ReplicatedStorage = game:GetService("ReplicatedStorage")
-local Matter = require(ReplicatedStorage.DevPackages.Matter)
-local ecr = require(ReplicatedStorage.DevPackages.ecr)
-local newWorld = Matter.World.new()
 
 local jecs = require(ReplicatedStorage.Lib:Clone())
 local mirror = require(ReplicatedStorage.mirror:Clone())
 local mcs = mirror.world()
 local ecs = jecs.world()
 
-local A1 = Matter.component()
-local A2 = Matter.component()
-local A3 = Matter.component()
-local A4 = Matter.component()
-local A5 = Matter.component()
-local A6 = Matter.component()
-local A7 = Matter.component()
-local A8 = Matter.component()
-
-local B1 = ecr.component()
-local B2 = ecr.component()
-local B3 = ecr.component()
-local B4 = ecr.component()
-local B5 = ecr.component()
-local B6 = ecr.component()
-local B7 = ecr.component()
-local B8 = ecr.component()
-
 local D1 = ecs:component()
 local D2 = ecs:component()
 local D3 = ecs:component()
@@ -47,90 +26,53 @@ local E6 = mcs:component()
 local E7 = mcs:component()
 local E8 = mcs:component()
 
-local registry2 = ecr.registry()
-
 local function flip()
-	return math.random() >= 0.25
+	return math.random() >= 0.3
 end
 
 local N = 2 ^ 16 - 2
-local archetypes = {}
 
-local hm = 0
 for i = 1, N do
-	local id = registry2.create()
-	local combination = ""
-	local n = newWorld:spawn()
 	local entity = ecs:entity()
 	local m = mcs:entity()
 
 	if flip() then
-		registry2:set(id, B1, { value = true })
-		ecs:set(entity, D1, { value = true })
-		newWorld:insert(n, A1({ value = true }))
-		mcs:set(m, E1, { value = 2 })
+		ecs:add(entity, entity)
+		mcs:add(m, m)
 	end
 	if flip() then
-		combination ..= "B"
-		registry2:set(id, B2, { value = true })
-		ecs:set(entity, D2, { value = true })
-		mcs:set(m, E2, { value = 2 })
-		newWorld:insert(n, A2({ value = true }))
+		ecs:set(entity, D1, true)
+		mcs:set(m, E1, true)
 	end
 	if flip() then
-		combination ..= "C"
-		registry2:set(id, B3, { value = true })
-		ecs:set(entity, D3, { value = true })
-		mcs:set(m, E3, { value = 2 })
-		newWorld:insert(n, A3({ value = true }))
+		ecs:set(entity, D2, true)
+		mcs:set(m, E2, true)
 	end
 	if flip() then
-		combination ..= "D"
-		registry2:set(id, B4, { value = true })
-		ecs:set(entity, D4, { value = true })
-		mcs:set(m, E4, { value = 2 })
-
-		newWorld:insert(n, A4({ value = true }))
+		ecs:set(entity, D3, true)
+		mcs:set(m, E3, true)
 	end
 	if flip() then
-		combination ..= "E"
-		registry2:set(id, B5, { value = true })
-		ecs:set(entity, D5, { value = true })
-		mcs:set(m, E5, { value = 2 })
-
-		newWorld:insert(n, A5({ value = true }))
+		ecs:set(entity, D4, true)
+		mcs:set(m, E4, true)
 	end
 	if flip() then
-		combination ..= "F"
-		registry2:set(id, B6, { value = true })
-		ecs:set(entity, D6, { value = true })
-		mcs:set(m, E6, { value = 2 })
-		newWorld:insert(n, A6({ value = true }))
+		ecs:set(entity, D5, true)
+		mcs:set(m, E5, true)
 	end
 	if flip() then
-		combination ..= "G"
-		registry2:set(id, B7, { value = true })
-		ecs:set(entity, D7, { value = true })
-		mcs:set(m, E7, { value = 2 })
-		newWorld:insert(n, A7({ value = true }))
+		ecs:set(entity, D6, true)
+		mcs:set(m, E6, true)
 	end
 	if flip() then
-		combination ..= "H"
-		registry2:set(id, B8, { value = true })
-		newWorld:insert(n, A8({ value = true }))
-		ecs:set(entity, D8, { value = true })
-		mcs:set(m, E8, { value = 2 })
+		ecs:set(entity, D7, true)
+		mcs:set(m, E7, true)
 	end
-
-	if combination:find("BCDF") then
-		if not archetypes[combination] then
-			print(combination)
+	if flip() then
+		ecs:set(entity, D8, true)
+		mcs:set(m, E8, true)
 	end
-		hm += 1
 end
-	archetypes[combination] = true
-end
-print("TEST", hm)
 
 local count = 0
 
@@ -138,7 +80,11 @@ for _, archetype in ecs:query(D2, D4, D6, D8):archetypes() do
 	count += #archetype.entities
 end
 
-print(count)
+
+local mq = mcs:query(E2, E4, E6, E8):cached()
+local jq = ecs:query(D2, D4, D6, D8):cached()
+
+print(count, #jq:archetypes())
 
 return {
 	ParameterGenerator = function()
@@ -157,12 +103,12 @@ return {
 		-- end,
 		--
 		Mirror = function()
-			for entityId, firstComponent in mcs:query(E2, E4, E6, E8) do
+			for entityId, firstComponent in mq do
 			end
 		end,
 
 		Jecs = function()
-			for entityId, firstComponent in ecs:query(D2, D4, D6, D8) do
+			for entityId, firstComponent in jq do
 			end
 		end,
 	},

docs/api/world.md

@@ -355,46 +355,9 @@ This operation is the same as calling:
 world:target(entity, jecs.ChildOf, 0)
 ```
 
-## contains
-
-Checks if an entity or component (id) exists in the world.
-
-```luau
-function World:contains(
-    entity: Entity,
-): boolean
-```
-
-Example:
-
-::: code-group
-
-```luau [luau]
-local entity = world:entity()
-print(world:contains(entity))
-print(world:contains(1))
-print(world:contains(2))
-
--- Outputs:
--- true
--- true
--- false
-```
-
-```ts [typescript]
-const entity = world.entity();
-print(world.contains(entity));
-print(world.contains(1));
-print(world.contains(2));
-
-// Outputs:
-// true
-// true
-// false
-```
-
 :::
 
+
 ## remove
 
 Removes a component (ID) from an entity
@@ -460,11 +423,11 @@ Example:
 
 ```luau [luau]
 local entity = world:entity()
-print(world:has(entity))
+print(world:contains(entity))
 
 world:delete(entity)
 
-print(world:has(entity))
+print(world:contains(entity))
 
 -- Outputs:
 -- true
@@ -601,7 +564,7 @@ print(retrievedParent === parent) // true
 
 ## contains
 
-Checks if an entity exists and is alive in the world.
+Checks if an entity or component (id) exists and is alive in the world.
 
 ```luau
 function World:contains(
@@ -640,12 +603,26 @@ function World:exists(
 
 ## cleanup
 
-Cleans up deleted entities and their associated data. This is automatically called by jecs, but can be called manually if needed.
+Cleans up empty archetypes.
 
 ```luau
 function World:cleanup(): void
 ```
 
+:::info
+It is recommended to profile the optimal interval you should cleanup because it varies completely from game to game.
+
+Here are a couple of reasons from Sander Mertens:
+	- some applications are memory constrained, so any wasted memory on empty
+	  archetypes has to get cleaned up
+	- many archetypes can get created during game startup but aren't used later
+	  on, so it would be wasteful to keep them around
+	- empty archetypes can slow queries down, especially if there are many more
+	  empty ones than non-empty ones
+	- if the total number of component permutations (/relationships) is too
+	  high, you have no choice but to periodically cleanup empty archetypes
+:::
+
 Example:
 
 ::: code-group

examples/luau/entities/basics.luau

@@ -1,15 +1,19 @@
 local jecs = require("@jecs")
-local world = jecs.World.new()
+local world = jecs.world()
 
-local Position = world:component()
+local Position = world:component() :: jecs.Id<vector>
 local Walking = world:component()
-local Name = world:component()
+local Name = world:component() :: jecs.Id<string>
+
+local function name(e: jecs.Entity): string
+	return assert(world:get(e, Name))
+end
 
 -- Create an entity with name Bob
 local bob = world:entity()
 
 -- The set operation finds or creates a component, and sets it.
-world:set(bob, Position, Vector3.new(10, 20, 30))
+world:set(bob, Position, vector.create(10, 20, 30))
 -- Name the entity Bob
 world:set(bob, Name, "Bob")
 -- The add operation adds a component without setting a value. This is
@@ -18,15 +22,16 @@ world:add(bob, Walking)
 
 -- Get the value for the Position component
 local pos = world:get(bob, Position)
-print(`\{{pos.X}, {pos.Y}, {pos.Z}\}`)
+assert(pos)
+print(`\{{pos.x}, {pos.y}, {pos.z}\}`)
 
 -- Overwrite the value of the Position component
-world:set(bob, Position, Vector3.new(40, 50, 60))
+world:set(bob, Position, vector.create(40, 50, 60))
 
 local alice = world:entity()
 -- Create another named entity
 world:set(alice, Name, "Alice")
-world:set(alice, Position, Vector3.new(10, 20, 30))
+world:set(alice, Position, vector.create(10, 20, 30))
 world:add(alice, Walking)
 
 -- Remove tag
@@ -34,7 +39,7 @@ world:remove(alice, Walking)
 
 -- Iterate all entities with Position
 for entity, p in world:query(Position) do
-	print(`{entity}: \{{p.X}, {p.Y}, {p.Z}\}`)
+	print(`{name(entity)}: \{{p.x}, {p.y}, {p.z}\}`)
 end
 
 -- Output:

examples/luau/queries/archetypes/targets.luau

@@ -0,0 +1,60 @@
+-- Using world:target is the recommended way to grab the target in a wildcard
+-- query. However the random access can add up in very hot paths. Accessing its
+-- column can drastically improve performance, especially when there are
+-- multiple adjacent pairs.
+
+local jecs = require("@jecs")
+local pair = jecs.pair
+local __ = jecs.Wildcard
+
+local world = jecs.world()
+
+local Likes = world:entity()
+local function name(e, name: string): string
+	if name then
+		world:set(e, jecs.Name, name)
+		return name
+	end
+	return assert(world:get(e, jecs.Name))
+end
+
+local e1 = world:entity()
+name(e1, "e1")
+local e2 = world:entity()
+name(e2, "e2")
+local e3 = world:entity()
+name(e3, "e3")
+
+world:add(e1, pair(Likes, e2))
+world:add(e1, pair(Likes, e3))
+
+local likes = jecs.component_record(world, pair(Likes, __))
+assert(likes)
+
+local likes_cr = likes.records
+local likes_counts = likes.counts
+
+local archetypes = world:query(pair(Likes, __)):archetypes()
+
+for _, archetype in archetypes do
+	local types = archetype.types
+
+	-- Get the starting index which is what the (R, *) alias is at
+	local wc = likes_cr[archetype.id]
+	local count = likes_counts[archetype.id]
+
+	local entities = archetype.entities
+	for i = #entities, 1, -1 do
+		-- It is generally a good idea to iterate backwards on arrays if you
+		-- need to delete the iterated entity to prevent iterator invalidation
+		local entity = entities[i]
+		for cr = wc, wc + count - 1 do
+			local person = jecs.pair_second(world, types[cr])
+			print(`entity ${entity} likes ${person}`)
+		end
+	end
+end
+
+-- Output:
+--  entity $273 likes $275
+--  entity $273 likes $274

examples/luau/queries/archetypes/visibility_cascades.luau

@@ -0,0 +1,44 @@
+-- To get the most out of performance, you can lift the inner loop of queries to
+-- the system in which you can do archetype-specific optimizations like finding
+-- the parent once per archetype rather than per entity.
+
+local jecs = require("@jecs")
+local pair = jecs.pair
+local ChildOf = jecs.ChildOf
+local __ = jecs.Wildcard
+
+local world = jecs.world()
+
+local Position = world:component() :: jecs.Id<vector>
+local Visible = world:entity()
+
+local parent = world:entity()
+world:set(parent, Position, vector.zero)
+world:add(parent, Visible)
+
+local child = world:entity()
+world:set(child, Position, vector.one)
+world:add(child, pair(ChildOf, parent))
+
+local parents = jecs.component_record(world, pair(ChildOf, __))
+assert(parents)
+
+local parent_cr = parents.records
+
+local archetypes = world:query(Position, pair(ChildOf, __)):archetypes()
+
+for _, archetype in archetypes do
+	local types = archetype.types
+	local p = jecs.pair_second(world, types[parent_cr[archetype.id]])
+	if world:has(p, Visible) then
+		local columns = archetype.columns_map
+		local positions = columns[Position]
+	  	for row, entity in archetype.entities do
+			local pos = positions[row]
+			print(`Child ${entity} of ${p} is visible at {pos}`)
+		end
+	end
+end
+
+-- Output:
+--  Child $274 of $273 is visibile at 1,1,1

examples/luau/queries/basics.luau

@@ -1,5 +1,5 @@
 local jecs = require("@jecs")
-local world = jecs.World.new()
+local world = jecs.world()
 
 local Position = world:component()
 local Velocity = world:component()

examples/luau/queries/changetracking.luau

@@ -1,19 +1,16 @@
 local jecs = require("@jecs")
 local pair = jecs.pair
 
-local world = jecs.World.new()
-local Name = world:component()
+local world = jecs.world()
+local Name = world:component() :: jecs.Id<string>
 
-local function named(ctr, name)
-	local e = ctr(world)
-	world:set(e, Name, name)
-	return e
-end
-local function name(e)
-	return world:get(e, Name)
+
+local function name(e: jecs.Entity): string
+	return assert(world:get(e, Name))
 end
 
-local Position = named(world.component, "Position") :: jecs.Entity<vector>
+local Position = world:component() :: jecs.Id<vector>
+world:set(Position, Name, "Position")
 local Previous = jecs.Rest
 
 local added = world
@@ -29,10 +26,14 @@ local removed = world
 	:cached()
 
 
-local e1 = named(world.entity, "e1")
+local e1 = world:entity()
+world:set(e1, Name, "e1")
 world:set(e1, Position, vector.create(10, 20, 30))
-local e2 = named(world.entity, "e2")
+
+local e2 = world:entity()
+world:set(e2, Name, "e2")
 world:set(e2, Position, vector.create(10, 20, 30))
+
 for entity, p in added do
 	print(`Added {name(entity)}: \{{p.x}, {p.y}, {p.z}}`)
 	world:set(entity, pair(Previous, Position), p)
@@ -40,10 +41,10 @@ end
 
 world:set(e1, Position, vector.create(999, 999, 1998))
 
-for _, archetype in changed:archetypes() do
+for entity, new, old in changed do
 	if new ~= old then
-		print(`{name(e)}'s Position changed from \{{old.x}, {old.y}, {old.z}\} to \{{new.x}, {new.y}, {new.z}\}`)
-		world:set(e, pair(Previous, Position), new)
+		print(`{name(entity)}'s Position changed from \{{old.x}, {old.y}, {old.z}\} to \{{new.x}, {new.y}, {new.z}\}`)
+		world:set(entity, pair(Previous, Position), new)
 	end
 end
 

examples/luau/queries/spatial_grids.luau

@@ -3,32 +3,47 @@ local pair = jecs.pair
 local ChildOf = jecs.ChildOf
 local __ = jecs.Wildcard
 local Name = jecs.Name
-local world = jecs.World.new()
+local world = jecs.world()
 
-type Id<T = nil> = number & { __T: T }
-local Voxel = world:component() :: Id
-local Position = world:component() :: Id<Vector3>
-local Perception = world:component() :: Id<{
+local Voxel = world:component() :: jecs.Id
+local Position = world:component() :: jecs.Id<vector>
+local Perception = world:component() :: jecs.Id<{
 	range: number,
 	fov: number,
-	dir: Vector3,
+	dir: vector,
 }>
-local PrimaryPart = world:component() :: Id<Part>
+type part = {
+	Position: vector
+}
+local PrimaryPart = world:component() :: jecs.Id<part>
 
-local local_player = game:GetService("Players").LocalPlayer
+local local_player = {
+	Character = {
+		PrimaryPart = {
+			Position = vector.create(50, 0, 30)
+		}
+	}
+}
+local workspace = {
+	CurrentCamera = {
+		CFrame = {
+			LookVector = vector.create(0, 0, -1)
+		}
+	}
+}
 
-local function distance(a: Vector3, b: Vector3)
-	return (b - a).Magnitude
+local function distance(a: vector, b: vector)
+	return vector.magnitude((b - a))
 end
 
-local function is_in_fov(a: Vector3, b: Vector3, forward_dir: Vector3, fov_angle: number)
+local function is_in_fov(a: vector, b: vector, forward_dir: vector, fov_angle: number)
 	local to_target = b - a
 
-	local forward_xz = Vector3.new(forward_dir.X, 0, forward_dir.Z).Unit
-	local to_target_xz = Vector3.new(to_target.X, 0, to_target.Z).Unit
+	local forward_xz = vector.normalize(vector.create(forward_dir.x, 0, forward_dir.z))
+	local to_target_xz = vector.normalize(vector.create(to_target.x, 0, to_target.z))
 
-	local angle_to_target = math.deg(math.atan2(to_target_xz.Z, to_target_xz.X))
-	local forward_angle = math.deg(math.atan2(forward_xz.Z, forward_xz.X))
+	local angle_to_target = math.deg(math.atan2(to_target_xz.z, to_target_xz.x))
+	local forward_angle = math.deg(math.atan2(forward_xz.z, forward_xz.z))
 
 	local angle_difference = math.abs(forward_angle - angle_to_target)
 
@@ -42,7 +57,7 @@ end
 local map = {}
 local grid = 50
 
-local function add_to_voxel(source: number, position: Vector3, prev_voxel_id: number?)
+local function add_to_voxel(source: jecs.Entity, position: vector, prev_voxel_id: jecs.Entity?)
 	local hash = position // grid
 	local voxel_id = map[hash]
 	if not voxel_id then
@@ -79,7 +94,7 @@ local function update_camera_direction(dt: number)
 end
 
 local function perceive_enemies(dt: number)
-	local it = world:query(Perception, Position, PrimaryPart)
+	local it = world:query(Perception, Position, PrimaryPart):iter()
 	-- There is only going to be one entity matching the query
 	local e, self_perception, self_position, self_primary_part = it()
 
@@ -93,28 +108,28 @@ local function perceive_enemies(dt: number)
 
 		if is_in_fov(self_position, target_position, self_perception.dir, self_perception.fov) then
 			local p = target_position
-			print(`Entity {world:get(e, Name)} can see target {world:get(enemy, Name)} at ({p.X}, {p.Y}, {p.Z})`)
+			print(`Entity {world:get(e, Name)} can see target {world:get(enemy, Name)} at ({p.x}, {p.y}, {p.z})`)
 		end
 	end
 end
 
 local player = world:entity()
 world:set(player, Perception, {
-	range = 100,
+	range = 200,
 	fov = 90,
-	dir = Vector3.new(1, 0, 0),
+	dir = vector.create(1, 0, 0),
 })
 world:set(player, Name, "LocalPlayer")
-local primary_part = (local_player.Character :: Model).PrimaryPart :: Part
+local primary_part = local_player.Character.PrimaryPart
 world:set(player, PrimaryPart, primary_part)
-world:set(player, Position, Vector3.zero)
+world:set(player, Position, vector.zero)
 
 local enemy = world:entity()
 world:set(enemy, Name, "Enemy $1")
-world:set(enemy, Position, Vector3.new(50, 0, 20))
+world:set(enemy, Position, vector.create(50, 0, 20))
 
 add_to_voxel(player, primary_part.Position)
-add_to_voxel(enemy, world)
+add_to_voxel(enemy, assert(world:get(enemy, Position)))
 
 local dt = 1 / 60
 reconcile_client_owned_assembly_to_voxel(dt)

jecs.d.ts

@@ -7,10 +7,14 @@ export type Entity<TData = unknown> = number & {
 	readonly __type_TData: TData;
 };
 
+type TagDiscriminator = {
+	readonly __nominal_Tag: unique symbol;
+};
+
 /**
  * An entity with no associated data when used as a component
  */
-export type Tag = Entity<undefined>;
+export type Tag = Entity<TagDiscriminator>;
 
 /**
  * A pair of entities:
@@ -26,12 +30,12 @@ export type Pair<P = unknown, O = unknown> = number & {
  * An `Id` can be either a single Entity or a Pair of Entities.
  * By providing `TData`, you can specifically require an Id that yields that type.
  */
-export type Id<TData = unknown> = Entity<TData> | Pair<TData, unknown> | Pair<undefined, TData>;
+export type Id<TData = unknown> = Entity<TData> | Pair<TData, unknown> | Pair<TagDiscriminator, TData>;
 
 export type InferComponent<E> = E extends Entity<infer D>
 	? D
 	: E extends Pair<infer P, infer O>
-	? P extends undefined
+	? P extends TagDiscriminator
 		? O
 		: P
 	: never;
@@ -43,22 +47,30 @@ type InferComponents<A extends Id[]> = { [K in keyof A]: InferComponent<A[K]> };
 type ArchetypeId = number;
 export type Column<T> = T[];
 
-export type Archetype<T extends unknown[]> = {
+export type Archetype<T extends Id[]> = {
 	id: number;
-	types: number[];
+	types: Entity[];
 	type: string;
-	entities: number[];
+	entities: Entity[];
 	columns: Column<unknown>[];
-	columns_map: Record<Id, Column<T[number]>>
+	columns_map: { [K in T[number]]: Column<InferComponent<K>> };
 };
 
-type Iter<T extends unknown[]> = IterableFunction<LuaTuple<[Entity, ...T]>>;
+type IterFn<T extends Id[]> = IterableFunction<LuaTuple<[Entity, ...InferComponents<T>]>>;
+type Iter<T extends Id[]> = IterFn<T> & {
+	/**
+	 * This isn't callable
+	 * @hidden
+	 * @deprecated
+	 */
+	(): never
+};
 
-export type CachedQuery<T extends unknown[]> = {
+export type CachedQuery<T extends Id[]> = {
 	/**
 	 * Returns an iterator that produces a tuple of [Entity, ...queriedComponents].
 	 */
-	iter(): Iter<T>;
+	iter(): IterFn<T>;
 
 	/**
 	 * Returns the matched archetypes of the query
@@ -67,11 +79,11 @@ export type CachedQuery<T extends unknown[]> = {
 	archetypes(): Archetype<T>[];
 } & Iter<T>;
 
-export type Query<T extends unknown[]> = {
+export type Query<T extends Id[]> = {
 	/**
 	 * Returns an iterator that produces a tuple of [Entity, ...queriedComponents].
 	 */
-	iter(): Iter<T>;
+	iter(): IterFn<T>;
 
 	/**
 	 * Creates and returns a cached version of this query for efficient reuse.
@@ -119,7 +131,7 @@ export class World {
 	 * @returns An entity (Tag) with no data.
 	 */
 	entity(): Tag;
-	entity<T extends Entity>(id: T): InferComponent<T> extends undefined ? Tag : T;
+	entity<T extends Entity>(id: T): T;
 
 	/**
 	 * Creates a new entity in the first 256 IDs, typically used for static
@@ -148,7 +160,7 @@ export class World {
 	 * @param entity The target entity.
 	 * @param component The component (or tag) to add.
 	 */
-	add<C>(entity: Entity, component: undefined extends InferComponent<C> ? C : Id<undefined>): void;
+	add<C>(entity: Entity, component: TagDiscriminator extends InferComponent<C> ? C : Id<TagDiscriminator>): void;
 
 	/**
 	 * Installs a hook on the given component.
@@ -172,6 +184,11 @@ export class World {
 	 */
 	cleanup(): void;
 
+	/**
+	 * Removes all instances of specified component
+	 */
+	// purge<T>(component: Id<T>): void
+
 	/**
 	 * Clears all components and relationships from the given entity, but
 	 * does not delete the entity from the world.
@@ -219,6 +236,12 @@ export class World {
 	 */
 	contains(entity: Entity): boolean;
 
+	/**
+	 * Checks if an entity exists in the world.
+	 * @param entity The entity to verify.
+	 */
+	contains(entity: number): entity is Entity;
+
 	/**
 	 * Checks if an entity with the given ID is currently alive, ignoring its generation.
 	 * @param entity The entity to verify.
@@ -246,11 +269,11 @@ export class World {
 	 * @param components The list of components to query.
 	 * @returns A Query object to iterate over results.
 	 */
-	query<T extends Id[]>(...components: T): Query<InferComponents<T>>;
+	query<T extends Id[]>(...components: T): Query<T>;
 
-	added<T>(component: Entity<T>, listener: (e: Entity, id: Id<T>, value: T) => void): () => void
-	changed<T>(component: Entity<T>, listener: (e: Entity, id: Id<T>, value: T) => void): () => void
-	removed<T>(component: Entity<T>, listener: (e: Entity, id: Id<T>) => void): () => void
+	added<T>(component: Entity<T>, listener: (e: Entity, id: Id<T>, value: T) => void): () => void;
+	changed<T>(component: Entity<T>, listener: (e: Entity, id: Id<T>, value: T) => void): () => void;
+	removed<T>(component: Entity<T>, listener: (e: Entity, id: Id<T>) => void): () => void;
 }
 
 export function world(): World;
@@ -297,11 +320,11 @@ export function ECS_PAIR_FIRST(pair: Pair): number;
 export function ECS_PAIR_SECOND(pair: Pair): number;
 
 type StatefulHook = Entity<<T>(e: Entity<T>, id: Id<T>, data: T) => void> & {
-	readonly __nominal_StatefulHook: unique symbol,
-}
+	readonly __nominal_StatefulHook: unique symbol;
+};
 type StatelessHook = Entity<<T>(e: Entity<T>, id: Id<T>) => void> & {
-	readonly __nominal_StatelessHook: unique symbol,
-}
+	readonly __nominal_StatelessHook: unique symbol;
+};
 
 export declare const OnAdd: StatefulHook;
 export declare const OnRemove: StatelessHook;
@@ -319,12 +342,34 @@ export declare const Exclusive: Tag;
 export declare const Rest: Entity;
 
 export type ComponentRecord = {
-	records: Map<Id, number>,
-	counts: Map<Id, number>,
-	size: number,
-}
+	records: Map<Id, number>;
+	counts: Map<Id, number>;
+	size: number;
+};
 
-export function component_record(world: World, id: Id): ComponentRecord
+export function component_record(world: World, id: Id): ComponentRecord;
 
-export function bulk_insert<const C extends Id[]>(world: World, entity: Entity, ids: C, values: InferComponents<C>): void
-export function bulk_remove(world: World, entity: Entity, ids: Id[]): void
+type TagToUndefined<T> = T extends TagDiscriminator ? undefined : T
+type TrimOptional<T extends unknown[]> = T extends [...infer L, infer R] 
+	? unknown extends R 
+		? L | T | TrimOptional<L> 
+		: R extends undefined
+			? L | T | TrimOptional<L>
+			: T
+	: T
+
+export function bulk_insert<const C extends Id[]>(
+	world: World,
+	entity: Entity,
+	ids: C,
+	values: TrimOptional<{ [K in keyof C]: TagToUndefined<InferComponent<C[K]>> }>,
+): void;
+export function bulk_remove(world: World, entity: Entity, ids: Id[]): void;
+
+export type EntityRecord<T extends Id[]> = {
+	archetype: Archetype<T>,
+	row: number,
+	dense: number,
+};
+
+export function record<T extends Id[] = []>(world: World, entity: Entity): EntityRecord<T>;

package.json

@@ -1,6 +1,6 @@
 {
 	"name": "@rbxts/jecs",
-	"version": "0.9.0-rc.9",
+	"version": "0.9.0",
 	"description": "Stupidly fast Entity Component System",
 	"main": "jecs.luau",
 	"repository": {

test/addons/ob.luau

@@ -0,0 +1,392 @@
+local jecs = require("@jecs")
+local testkit = require("@testkit")
+local test = testkit.test()
+local CASE, TEST, FINISH, CHECK = test.CASE, test.TEST, test.FINISH, test.CHECK
+local FOCUS = test.FOCUS
+local ob = require("@addons/ob")
+
+TEST("addons/ob::observer", function()
+	local world = jecs.world()
+	do CASE "should match against archetypes that were already created"
+		local A = world:component()
+
+		local e1 = world:entity()
+		world:add(e1, A)
+
+		local c = 1
+		ob.observer(world:query(A), function()
+			c+=1
+		end)
+
+		world:remove(e1, A)
+		world:add(e1, A)
+		CHECK(c==2)
+	end
+
+	do CASE "Should enter observer at query:without(pair(R, t1)) when adding pair(R, t2)"
+		local A = world:component()
+		local B = world:component()
+		local C = world:component()
+		local D = world:component()
+
+		local e = world:entity()
+		world:add(e, A)
+		world:add(e, jecs.pair(B, D))
+
+		local c = 1
+
+		ob.observer(world:query(A):without(jecs.pair(B, C)), function()
+			c += 1
+		end)
+
+		local child = world:entity()
+		world:add(child, A)
+		CHECK(c==2)
+		world:add(child, jecs.pair(B, D))
+		CHECK(c==2)
+		world:add(child, jecs.pair(B, C))
+		CHECK(c==2)
+	end
+
+	do CASE "Should enter observer at query:without(pair(R, t1)) when removing pair(R, t1)"
+		local A = world:component()
+		local B = world:component()
+		local C = world:component()
+		local D = world:component()
+
+		local e = world:entity()
+		world:add(e, A)
+		world:add(e, jecs.pair(B, D))
+
+		local c = 1
+		ob.observer(world:query(A):without(jecs.pair(B, D)), function()
+			c += 1
+		end)
+
+		local child = world:entity()
+		world:add(child, jecs.pair(B, C))
+		world:add(child, jecs.pair(B, D))
+		CHECK(c==1)
+		world:add(child, A)
+		CHECK(c==1)
+		world:remove(child, jecs.pair(B, C))
+		CHECK(c==1)
+		world:add(child, jecs.pair(B, C))
+		CHECK(c==1)
+		world:remove(child, jecs.pair(B, D))
+		CHECK(c==2)
+		world:add(child, jecs.pair(B, D))
+		CHECK(c==2)
+		world:remove(child, jecs.pair(B, C))
+		CHECK(c==2)
+		world:remove(child, jecs.pair(B, D))
+		CHECK(c==3)
+	end
+
+	do CASE "Should enter observer at query:without(pair(R, *)) when adding pair(R, t1)"
+		local A = world:component()
+		local B = world:component()
+		local C = world:component()
+		local D = world:component()
+
+		local c = 1
+		ob.observer(world:query(A):without(jecs.pair(B, jecs.w)), function() c+= 1 end)
+
+		local child = world:entity()
+		world:add(child, A)
+		CHECK(c==2)
+		world:add(child, jecs.pair(B, D))
+		CHECK(c==2)
+		world:add(child, jecs.pair(B, C))
+		CHECK(c==2)
+	end
+
+	do CASE "Should enter observer at query:without(t1) when removing t1"
+		local A = world:component()
+		local B = world:component()
+
+		local c = 1
+		ob.observer(world:query(A):without(B), function() c+= 1 end)
+
+		local child = world:entity()
+		world:add(child, B)
+		CHECK(c==1)
+		world:add(child, A)
+		CHECK(c==1)
+		world:remove(child, B)
+		CHECK(c==2)
+		world:remove(child, A)
+		CHECK(c==2)
+	end
+
+	do CASE "observers should accept pairs"
+		local A = world:component()
+		local B = world:component()
+
+		local c = 1
+		ob.observer(world:query(jecs.pair(A, B)), function() c+= 1 end)
+
+		local child = world:entity()
+		world:add(child, jecs.pair(A, B))
+		CHECK(c == 2)
+
+		world:remove(child, jecs.pair(A, B))
+		CHECK(c == 2)
+	end
+
+	do CASE "Ensure ordering between signals and observers"
+		local A = world:component()
+		local B = world:component()
+
+		local count = 1
+		local function counter()
+			count += 1
+		end
+
+		ob.observer(world:query(A, B), counter)
+
+		world:added(A, counter)
+		world:added(A, counter)
+
+		for _ in world:query(A) do
+
+		end
+
+		local e = world:entity()
+		world:add(e, A)
+		CHECK(count == 3)
+
+		world:add(e, B)
+		CHECK(count == 4)
+	end
+
+	do CASE "Rematch entities in observers"
+		local A = world:component()
+
+		local count = 1
+		local function counter()
+			count += 1
+		end
+
+		ob.observer(world:query(A), counter)
+
+		local e = world:entity()
+		world:set(e, A, false)
+		CHECK(count == 2)
+		world:remove(e, A)
+		CHECK(count == 2)
+		world:set(e, A, false)
+		CHECK(count == 3)
+		world:set(e, A, false)
+		CHECK(count == 4)
+	end
+
+	do CASE "Call off pairs"
+		local A = world:component()
+
+		local callcount = 1
+		world:added(A, function(entity)
+			callcount += 1
+		end)
+		world:added(A, function(entity)
+			callcount += 1
+		end)
+
+		local e = world:entity()
+		local e2 = world:entity()
+
+		world:add(e2, jecs.pair(A, e))
+		world:add(e, jecs.pair(A, e2))
+		CHECK(callcount == 1 + 2 * 2)
+	end
+end)
+
+TEST("addons/ob::monitor", function()
+	local world = jecs.world()
+	do CASE "should match against archetypes that were already created"
+		local A = world:component()
+
+		local e1 = world:entity()
+		world:add(e1, A)
+
+		local monitor = ob.monitor(world:query(A))
+		local c = 1
+		monitor.added(function()
+			c += 1
+		end)
+
+		world:remove(e1, A)
+		world:add(e1, A)
+		CHECK(c==2)
+	end
+
+	do CASE "Should enter monitor at query:without(pair(R, t1)) when adding pair(R, t2)"
+		local A = world:component()
+		local B = world:component()
+		local C = world:component()
+		local D = world:component()
+
+		local e = world:entity()
+		world:add(e, A)
+		world:add(e, jecs.pair(B, D))
+
+		local c = 1
+		local r = 1
+		local monitor = ob.monitor(world:query(A):without(jecs.pair(B, C)))
+		monitor.added(function()
+			c += 1
+		end)
+		monitor.removed(function()
+			r += 1
+		end)
+
+		local child = world:entity()
+		world:add(child, A)
+		CHECK(c==2)
+		world:add(child, jecs.pair(B, D))
+		CHECK(c==2)
+		CHECK(r==1)
+		world:add(child, jecs.pair(B, C))
+		CHECK(c==2)
+		CHECK(r==2)
+	end
+
+	do CASE "Should enter monitor at query:without(pair(R, t1)) when removing pair(R, t1)"
+		local A = world:component()
+		local B = world:component()
+		local C = world:component()
+		local D = world:component()
+
+		local e = world:entity()
+		world:add(e, A)
+		world:add(e, jecs.pair(B, D))
+
+		local c = 1
+		local r = 1
+		local monitor = ob.monitor(world:query(A):without(jecs.pair(B, D)))
+		monitor.added(function()
+			c += 1
+		end)
+		monitor.removed(function()
+			r += 1
+		end)
+
+		local child = world:entity()
+		world:add(child, jecs.pair(B, C))
+		world:add(child, jecs.pair(B, D))
+		CHECK(c==1)
+		world:add(child, A)
+		CHECK(c==1)
+		world:remove(child, jecs.pair(B, C))
+		CHECK(c==1)
+		world:add(child, jecs.pair(B, C))
+		CHECK(c==1)
+		world:remove(child, jecs.pair(B, D))
+		CHECK(c==2)
+		world:add(child, jecs.pair(B, D))
+		CHECK(c==2)
+		CHECK(r==2)
+		world:remove(child, jecs.pair(B, C))
+		CHECK(c==2)
+		CHECK(r==2)
+		world:remove(child, jecs.pair(B, D))
+		CHECK(c==3)
+		CHECK(r==2)
+	end
+
+	do CASE "Should enter monitor at query:without(pair(R, *)) when adding pair(R, t1)"
+		local A = world:component()
+		local B = world:component()
+		local C = world:component()
+		local D = world:component()
+
+		local c = 1
+		local r = 1
+		local monitor = ob.monitor(world:query(A):without(jecs.pair(B, jecs.w)))
+		monitor.added(function()
+			c += 1
+		end)
+		monitor.removed(function()
+			r += 1
+		end)
+
+		local child = world:entity()
+		world:add(child, A)
+		CHECK(c==2)
+		world:add(child, jecs.pair(B, D))
+		CHECK(c==2)
+		CHECK(r==2)
+		world:add(child, jecs.pair(B, C))
+		CHECK(c==2)
+		CHECK(r==2)
+	end
+
+	do CASE "Should enter monitor at query:without(t1) when removing t1"
+		local A = world:component()
+		local B = world:component()
+
+		local c = 1
+		local monitor = ob.monitor(world:query(A):without(B))
+		monitor.added(function()
+			c += 1
+		end)
+		monitor.removed(function()
+			c += 1
+		end)
+
+		local child = world:entity()
+		world:add(child, B)
+		CHECK(c==1)
+		world:add(child, A)
+		CHECK(c==1)
+		world:remove(child, B)
+		CHECK(c==2)
+		world:remove(child, A)
+		CHECK(c==3)
+	end
+
+	do CASE "monitors should accept pairs"
+		local A = world:component()
+		local B = world:component()
+
+		local c = 1
+		local monitor = ob.monitor(world:query(jecs.pair(A, B)))
+		monitor.added(function()
+			c += 1
+		end)
+		monitor.removed(function()
+			c += 1
+		end)
+
+		local child = world:entity()
+		world:add(child, jecs.pair(A, B))
+		CHECK(c == 2)
+
+		world:remove(child, jecs.pair(A, B))
+		CHECK(c == 3)
+	end
+
+	do CASE "Don't report changed components in monitor"
+		local A = world:component()
+		local count = 1
+		local function counter()
+			count += 1
+		end
+
+		local monitor = ob.monitor(world:query(A))
+		monitor.added(counter)
+		monitor.removed(counter)
+
+		local e = world:entity()
+		world:set(e, A, false)
+		CHECK(count == 2)
+		world:remove(e, A)
+		CHECK(count == 3)
+		world:set(e, A, false)
+		CHECK(count == 4)
+		world:set(e, A, false)
+		CHECK(count == 4)
+	end
+end)
+
+return FINISH()

test/addons/observers.luau

@@ -1,114 +0,0 @@
-local jecs = require("@jecs")
-local testkit = require("@testkit")
-local test = testkit.test()
-local CASE, TEST, FINISH, CHECK = test.CASE, test.TEST, test.FINISH, test.CHECK
-local FOCUS = test.FOCUS
-local ob = require("@addons/ob")
-
-TEST("addons/observers", function()
-
-	local world = jecs.world()
-	do CASE "monitors should accept pairs"
-		local A = world:component()
-		local B = world:component()
-
-		local c = 1
-		ob.monitor(world:query(jecs.pair(A, B)), function (_, event)
-			c += 1
-		end)
-
-		local child = world:entity()
-		world:add(child, jecs.pair(A, B))
-		CHECK(c == 2)
-
-		world:remove(child, jecs.pair(A, B))
-		CHECK(c == 3)
-	end
-	do CASE "Ensure ordering between signals and observers"
-		local A = world:component()
-		local B = world:component()
-
-		local count = 1
-		local function counter()
-			count += 1
-		end
-
-		ob.observer(world:query(A, B), counter)
-
-		world:added(A, counter)
-		world:added(A, counter)
-
-		for _ in world:query(A) do
-
-		end
-
-		local e = world:entity()
-		world:add(e, A)
-		CHECK(count == 3)
-
-		world:add(e, B)
-		CHECK(count == 4)
-	end
-
-	do CASE "Rematch entities in observers"
-		local A = world:component()
-
-		local count = 1
-		local function counter()
-			count += 1
-		end
-
-		ob.observer(world:query(A), counter)
-
-		local e = world:entity()
-		world:set(e, A, false)
-		CHECK(count == 2)
-		world:remove(e, A)
-		CHECK(count == 2)
-		world:set(e, A, false)
-		CHECK(count == 3)
-		world:set(e, A, false)
-		CHECK(count == 4)
-	end
-
-	do CASE "Don't report changed components in monitor"
-		local A = world:component()
-		local count = 1
-		local function counter()
-			count += 1
-		end
-
-		ob.monitor(world:query(A), counter)
-
-		local e = world:entity()
-		world:set(e, A, false)
-		CHECK(count == 2)
-		world:remove(e, A)
-		CHECK(count == 3)
-		world:set(e, A, false)
-		CHECK(count == 4)
-		world:set(e, A, false)
-		CHECK(count == 4)
-	end
-
-	do CASE "Call off pairs"
-		local A = world:component()
-
-		local callcount = 1
-		world:added(A, function(entity)
-			callcount += 1
-		end)
-		world:added(A, function(entity)
-			callcount += 1
-		end)
-
-		local e = world:entity()
-		local e2 = world:entity()
-
-		world:add(e2, jecs.pair(A, e))
-		world:add(e, jecs.pair(A, e2))
-		CHECK(callcount == 1 + 2 * 2)
-	end
-end)
-
-return FINISH()

test/tests.luau

@@ -24,38 +24,6 @@ type Id<T=unknown> = jecs.Id<T>
 local entity_visualiser = require("@tools/entity_visualiser")
 local dwi = entity_visualiser.stringify
 
-TEST("ardi", function()
-	local world = jecs.world()
-	local r = world:entity()
-	world:add(r, jecs.pair(jecs.OnDelete, jecs.Delete))
-
-	local e = world:entity()
-	local e1 = world:entity()
-	world:add(e, jecs.pair(r, e1))
-
-	world:delete(r)
-	CHECK(not world:contains(e))
-end)
-
-TEST("dai", function()
-	local world = jecs.world()
-	local C = world:component()
-
-	world:set(C, jecs.Name, "C")
-	CHECK(world:get(C, jecs.Name) == "C")
-	world:entity(2000)
-	CHECK(world:get(C, jecs.Name) == "C")
-end)
-
-TEST("another axen banger", function()
-	-- taken from jecs.luau
-	local world = jecs.world()
-	world:range(2000, 3000)
-
-	local e0v1_id = jecs.ECS_COMBINE(1000, 1) -- id can be both within or outside the world's range
-	local e0v1 = world:entity(e0v1_id)
-	assert(world:contains(e0v1)) -- fails
-end)
 TEST("Ensure archetype edges get cleaned", function()
 	local A = jecs.component()
 	local B = jecs.component()
@@ -90,6 +58,7 @@ TEST("Ensure archetype edges get cleaned", function()
 		CHECK(false)
 	end
 end)
+
 TEST("repeated entity cached query", function()
 	local pair = jecs.pair
 	local world = jecs.world()
@@ -148,7 +117,6 @@ TEST("repeated pairs", function()
 
 	local e2 = world:entity()
 
-	print("-----")
 	world:set(e2, p2, true)
 
 	CHECK(world:get(e2, p2))
@@ -190,7 +158,6 @@ TEST("repro", function()
 	end
 	CHECK(count == 1)
 	count = 0
-	print("----")
 	world:add(e2v1, jecs.pair(relation, e1v1))
 	CHECK(world:has(e2v1, jecs.pair(relation, e1v1)))
 
@@ -198,10 +165,11 @@ TEST("repro", function()
 		count += 1
 	end
 
-	print(count)
 	CHECK(count==1)
 end)
+
 TEST("bulk", function()
+	do CASE "Should allow components and tags to be in disorder"
 		local world = jecs.world()
 		local A = world:component()
 		local B = world:component()
@@ -292,6 +260,90 @@ TEST("bulk", function()
 		CHECK(world:has(e, E) == false)
 		CHECK(world:has(e, F) == false)
 		CHECK(world:has(e, G) == false)
+	end
+	do CASE "Should bulk add by default when there is no values"
+		local world = jecs.world()
+		local t1, t2, t3 = world:entity(), world:entity(), world:entity()
+		local count = 0
+		local function counter()
+			count += 1
+		end
+		world:added(t1, counter)
+		world:added(t2, counter)
+		world:added(t3, counter)
+
+		local e = world:entity()
+		jecs.bulk_insert(world, e, {t1,t2,t3}, {})
+
+		CHECK(world:has(e, t1, t2, t3))
+		CHECK(count == 3)
+	end
+
+	do CASE "Should bulk add by default when there is no values"
+		local world = jecs.world()
+		local c1, c2, c3 = world:component(), world:component(), world:component()
+		local count = 0
+		local function counter()
+			count += 1
+		end
+
+		world:changed(c1, counter)
+		world:changed(c2, counter)
+		world:changed(c3, counter)
+
+		local e = world:entity()
+		jecs.bulk_insert(world, e, {c1,c2,c3}, {1,2,3})
+
+		jecs.bulk_insert(world, e, {c1,c2,c3}, {4,5,6})
+
+		CHECK(world:has(e, c1, c2, c3))
+		CHECK(count == 3)
+	end
+
+	do CASE "Should bulk add with hooks moving archetypes without previous"
+		local world = jecs.world()
+		local c1, c2, c3 = world:component(), world:component(), world:component()
+
+		world:added(c1, function(e)
+			world:set(e, c3, "hello")
+		end)
+
+		local e = world:entity()
+		jecs.bulk_insert(world, e, {c1,c2}, {true, 123})
+		CHECK(world:get(e, c1) == true)
+		CHECK(world:get(e, c2) == 123)
+		CHECK(world:get(e, c3) == "hello")
+	end
+
+	do CASE "Should bulk add with hooks moving archetypes with previous"
+		local world = jecs.world()
+		local c1, c2, c3 = world:component(), world:component(), world:component()
+
+		world:added(c1, function(e)
+			world:set(e, c3, "hello")
+		end)
+
+		local e = world:entity()
+		world:add(e, world:entity())
+		jecs.bulk_insert(world, e, {c1,c2}, {true, 123})
+		CHECK(world:get(e, c1) == true)
+		CHECK(world:get(e, c2) == 123)
+		CHECK(world:get(e, c3) == "hello")
+	end
+
+	do CASE "Should ensure archetype ids are sorted"
+		local world = jecs.world()
+		local c1, c2, c3 = world:component(), world:component(), world:component()
+
+		local e = world:entity()
+		jecs.bulk_insert(world, e, { c2, c1 }, { 2, 1 })
+		jecs.bulk_insert(world, e, { c1 }, { 1 })
+		world:set(e, c3, 3)
+
+		CHECK(world:get(e, c1) == 1)
+		CHECK(world:get(e, c2) == 2)
+		CHECK(world:get(e, c3) == 3)
+	end
 end)
 
 TEST("repro", function()
@@ -319,7 +371,25 @@ TEST("repro", function()
 end)
 
 TEST("world:add()", function()
-	do CASE "exclusive relations"
+	do CASE "Removing exclusive pair should traverse backwards on edge"
+		local world = jecs.world()
+		local a = world:entity()
+		local b = world:entity()
+		local c = world:entity()
+
+		world:add(a, pair(ChildOf, b))
+		world:add(a, pair(ChildOf, c))
+
+		CHECK(not world:has(a, pair(ChildOf, b)))
+		CHECK(world:has(a, pair(ChildOf, c)))
+
+		world:remove(a, pair(ChildOf, c))
+
+		CHECK(not world:has(a, pair(ChildOf, b)))
+		CHECK(not world:has(a, pair(ChildOf, c)))
+		CHECK(not world:target(a, ChildOf))
+	end
+	do CASE "Exclusive relations"
 		local world = jecs.world()
 		local A = world:component()
 		world:add(A, jecs.Exclusive)
@@ -462,9 +532,9 @@ TEST("world:add()", function()
 end)
 
 TEST("world:children()", function()
-	local world = jecs.world()
 	local C = jecs.component()
 	local T = jecs.tag()
+	local world = jecs.world()
 
 	local e1 = world:entity()
 	world:set(e1, C, true)
@@ -503,100 +573,146 @@ TEST("world:children()", function()
 	jecs.ECS_META_RESET()
 end)
 
-TEST("world:clear()", function()
-	do CASE "should remove its components"
+-- TEST("world:purge()", function()
+-- 	do CASE "should remove all instances of specified component"
+-- 		local world = jecs.world()
+-- 		local A = world:component()
+-- 		local B = world:component()
+
+-- 		local e = world:entity()
+-- 		local e1 = world:entity()
+-- 		local _e2 = world:entity()
+
+-- 		world:set(e, A, true)
+-- 		world:set(e, B, true)
+
+-- 		world:set(e1, A, true)
+-- 		world:set(e1, B, true)
+
+-- 		CHECK(world:get(e, A))
+-- 		CHECK(world:get(e, B))
+
+-- 		world:purge(A)
+-- 		CHECK(world:get(e, A) == nil)
+-- 		CHECK(world:get(e, B))
+-- 		CHECK(world:get(e1, A) == nil)
+-- 		CHECK(world:get(e1, B))
+-- 	end
+
+-- 	do CASE "remove purged component from entities"
+-- 		local world = jecs.world()
+-- 		local A = world:component()
+-- 		local B = world:component()
+-- 		local C = world:component()
+
+-- 		do
+-- 			local id1 = world:entity()
+-- 			local id2 = world:entity()
+-- 			local id3 = world:entity()
+
+-- 			world:set(id1, A, true)
+
+-- 			world:set(id2, A, true)
+-- 			world:set(id2, B, true)
+
+-- 			world:set(id3, A, true)
+-- 			world:set(id3, B, true)
+-- 			world:set(id3, C, true)
+
+-- 			world:purge(A)
+
+-- 			CHECK(not world:has(id1, A))
+-- 			CHECK(not world:has(id2, A))
+-- 			CHECK(not world:has(id3, A))
+
+-- 			CHECK(world:has(id2, B))
+-- 			CHECK(world:has(id3, B, C))
+
+-- 			world:purge(C)
+
+-- 			CHECK(world:has(id2, B))
+-- 			CHECK(world:has(id3, B))
+
+-- 			CHECK(world:contains(A))
+-- 			CHECK(world:contains(C))
+-- 			CHECK(world:has(A, jecs.Component))
+-- 			CHECK(world:has(B, jecs.Component))
+-- 		end
+
+-- 		do
+-- 			local id1 = world:entity()
+-- 			local id2 = world:entity()
+-- 			local id3 = world:entity()
+
+-- 			local tgt = world:entity()
+
+-- 			world:add(id1, pair(A, tgt))
+-- 			world:add(id1, pair(B, tgt))
+-- 			world:add(id1, pair(C, tgt))
+
+-- 			world:add(id2, pair(A, tgt))
+-- 			world:add(id2, pair(B, tgt))
+-- 			world:add(id2, pair(C, tgt))
+
+-- 			world:add(id3, pair(A, tgt))
+-- 			world:add(id3, pair(B, tgt))
+-- 			world:add(id3, pair(C, tgt))
+
+-- 			world:purge(B)
+-- 			CHECK(world:has(id1, pair(A, tgt), pair(C, tgt)))
+-- 			CHECK(not world:has(id1, pair(B, tgt)))
+-- 			CHECK(world:has(id2, pair(A, tgt), pair(C, tgt)))
+-- 			CHECK(not world:has(id1, pair(B, tgt)))
+-- 			CHECK(world:has(id3, pair(A, tgt), pair(C, tgt)))
+
+-- 		end
+
+-- 	end
+-- end)
+
+TEST("world:clear", function()
+	do CASE "remove all components on entity"
 		local world = jecs.world()
 		local A = world:component()
 		local B = world:component()
 
 		local e = world:entity()
-		local e1 = world:entity()
-		local _e2 = world:entity()
 
 		world:set(e, A, true)
 		world:set(e, B, true)
 
-		world:set(e1, A, true)
-		world:set(e1, B, true)
+		world:clear(e)
 
-		CHECK(world:get(e, A))
-		CHECK(world:get(e, B))
-
-		world:clear(A)
-		CHECK(world:get(e, A) == nil)
-		CHECK(world:get(e, B))
-		CHECK(world:get(e1, A) == nil)
-		CHECK(world:get(e1, B))
+		CHECK(world:contains(e))
+		CHECK(not world:has(e, A))
+		CHECK(not world:has(e, B))
+		print(jecs.record(world, e).archetype == nil::any)
 	end
 
-	do CASE "remove cleared ID from entities"
+	do CASE "should invoke hooks"
 		local world = jecs.world()
 		local A = world:component()
+		local called = 0
+		world:set(A, jecs.OnRemove, function()
+			called += 1
+		end)
+
 		local B = world:component()
-		local C = world:component()
+		world:set(B, jecs.OnRemove, function()
+			called += 1
+		end)
 
-		do
-			local id1 = world:entity()
-			local id2 = world:entity()
-			local id3 = world:entity()
+		local e = world:entity()
 
-			world:set(id1, A, true)
+		world:set(e, A, true)
+		world:set(e, B, true)
 
-			world:set(id2, A, true)
-			world:set(id2, B, true)
-
-			world:set(id3, A, true)
-			world:set(id3, B, true)
-			world:set(id3, C, true)
-
-			world:clear(A)
-
-			CHECK(not world:has(id1, A))
-			CHECK(not world:has(id2, A))
-			CHECK(not world:has(id3, A))
-
-			CHECK(world:has(id2, B))
-			CHECK(world:has(id3, B, C))
-
-			world:clear(C)
-
-			CHECK(world:has(id2, B))
-			CHECK(world:has(id3, B))
-
-			CHECK(world:contains(A))
-			CHECK(world:contains(C))
-			CHECK(world:has(A, jecs.Component))
-			CHECK(world:has(B, jecs.Component))
-		end
-
-		do
-			local id1 = world:entity()
-			local id2 = world:entity()
-			local id3 = world:entity()
-
-			local tgt = world:entity()
-
-			world:add(id1, pair(A, tgt))
-			world:add(id1, pair(B, tgt))
-			world:add(id1, pair(C, tgt))
-
-			world:add(id2, pair(A, tgt))
-			world:add(id2, pair(B, tgt))
-			world:add(id2, pair(C, tgt))
-
-			world:add(id3, pair(A, tgt))
-			world:add(id3, pair(B, tgt))
-			world:add(id3, pair(C, tgt))
-
-			world:clear(B)
-			CHECK(world:has(id1, pair(A, tgt), pair(C, tgt)))
-			CHECK(not world:has(id1, pair(B, tgt)))
-			CHECK(world:has(id2, pair(A, tgt), pair(C, tgt)))
-			CHECK(not world:has(id1, pair(B, tgt)))
-			CHECK(world:has(id3, pair(A, tgt), pair(C, tgt)))
-
-		end
+		world:clear(e)
 
+		CHECK(world:contains(e))
+		CHECK(not world:has(e, A))
+		CHECK(not world:has(e, B))
+		CHECK(called == 2)
 	end
 end)
 
@@ -668,6 +784,81 @@ TEST("world:contains()", function()
 end)
 
 TEST("world:delete()", function()
+	do CASE "OnDelete cleanup policy cascades deletion to entites with idr_r pairs"
+		local world = jecs.world()
+		local r = world:entity()
+		world:add(r, jecs.pair(jecs.OnDelete, jecs.Delete))
+
+		local e = world:entity()
+		local e1 = world:entity()
+		world:add(e, jecs.pair(r, e1))
+
+		world:delete(r)
+		CHECK(not world:contains(e))
+	end
+
+	do CASE "OnDeleteTarget works correctly regardless of adjacent archetype iteration order"
+		local world = jecs.world()
+		local t = world:entity()
+		local c = world:component()
+		world:add(c, t)
+
+		local component = world:component()
+		local lifetime = world:component()
+
+		local tag = world:entity()
+		local rel1 = world:entity()
+		local rel2 = world:entity()
+		local rel3 = world:entity()
+
+		local destroyed = false
+
+		world:removed(lifetime, function(e)
+		    destroyed = true
+		end)
+
+		local parent = world:entity()
+		world:set(parent, component, "foo")
+		world:add(parent, jecs.pair(rel1, component))
+
+		local other1 = world:entity()
+		world:add(other1, tag)
+		world:add(other1, jecs.pair(jecs.ChildOf, parent))
+		world:add(other1, jecs.pair(rel1, component))
+
+		local child = world:entity()
+		world:set(child, lifetime, "")
+		world:add(child, jecs.pair(jecs.ChildOf, parent))
+		world:add(child, jecs.pair(rel3, parent))
+		world:add(child, jecs.pair(rel2, other1))
+
+		world:delete(parent)
+
+		CHECK(destroyed)
+		CHECK(not world:contains(child))
+	end
+	if true then
+		return
+	end
+
+	do CASE "Should delete children in different archetypes if they have the same parent"
+		local world = jecs.world()
+
+	    local component = world:entity()
+
+	    local parent = world:entity()
+
+	    local child = world:entity()
+	    world:add(child, jecs.pair(jecs.ChildOf, parent))
+
+	    local child2 = world:entity()
+	    world:add(child2, component) -- important, they need to be in different archetypes
+	    world:add(child2, jecs.pair(jecs.ChildOf, parent))
+
+	    world:delete(parent)
+	    CHECK(not world:contains(child))
+	    CHECK(not world:contains(child2)) -- fails
+	end
 	do CASE "idr_t//delete_mask@3102..3108"
 		local world = jecs.world()
 		local A = world:component()
@@ -704,7 +895,6 @@ TEST("world:delete()", function()
 		local world = jecs.world()
 		local A = world:component()
 		local B = world:component()
-		local C = world:component()
 		world:set(A, jecs.OnRemove, function(entity, id)
 			world:set(entity, B, true)
 		end)
@@ -1175,7 +1365,6 @@ TEST("world:added", function()
 	end
 
 	do CASE ""
-		local world = jecs.world()
 		local IsNearby = world:component()
 		world:set(IsNearby, jecs.Name, "IsNearby")
 		local person1, person2 = world:entity(), world:entity()
@@ -1212,7 +1401,6 @@ TEST("world:added", function()
 		end)
 
 		local entity = world:entity()
-		print(pair(A, B))
 		world:set(entity, pair(A, B), 3)
 		CHECK(ran)
 	end
@@ -1275,7 +1463,7 @@ TEST("world:range()", function()
 		CHECK(world.entity_index.alive_count == 400)
 		CHECK(e)
 	end
-	do CASE "axen"
+	do CASE "entity ID reuse works correctly across different world ranges"
 		local base = jecs.world()
 		base:range(1_000, 2_000)
 
@@ -1387,6 +1575,24 @@ TEST("world:range()", function()
 end)
 
 TEST("world:entity()", function()
+	do CASE "entity mirroring preserves IDs across world ranges"
+		local world = jecs.world()
+		world:range(2000, 3000)
+
+		local e0v1_id = jecs.ECS_COMBINE(1000, 1) -- id can be both within or outside the world's range
+		local e0v1 = world:entity(e0v1_id)
+		CHECK(world:contains(e0v1)) -- fails
+	end
+
+	do CASE "component names persist after entity creation"
+		local world = jecs.world()
+		local C = world:component()
+
+		world:set(C, jecs.Name, "C")
+		CHECK(world:get(C, jecs.Name) == "C")
+		world:entity(2000)
+		CHECK(world:get(C, jecs.Name) == "C")
+	end
 	do CASE "desired id"
 		local world = jecs.world()
 		local id = world:entity()
@@ -1502,6 +1708,36 @@ end)
 TEST("world:query()", function()
 	local N = 2^8
 
+	do CASE "queries should accept zero-ids provided they use :with for the leading component"
+		local world = jecs.world()
+		local A = world:component()
+		local B = world:component()
+
+		local e1 = world:entity()
+		world:set(e1, A, "A")
+
+		local e2 = world:entity()
+		world:set(e2, A, "A")
+		world:set(e2, B, "B")
+
+		for e, a in world:query():with(A) do
+			CHECK(e == e1 or e == e2)
+			CHECK(a == nil)
+			if e == e1 then
+				CHECK(world:has(e1, A))
+				CHECK(not world:has(e1, B))
+			elseif e == e2 then
+				CHECK(world:has(e2, A, B))
+			end
+		end
+		for e, a in world:query():with(A):without(B) do
+			CHECK(e == e1)
+			CHECK(a == nil)
+			CHECK(world:has(e1, A))
+			CHECK(not world:has(e1, B))
+		end
+	end
+
 	do CASE "cached"
 		local world = jecs.world()
 		local Foo = world:component()
@@ -1760,6 +1996,41 @@ TEST("world:query()", function()
 		end
 	end
 
+	do CASE "query more than 8 components"
+		local world = jecs.world()
+		local components = {}
+
+		for i = 1, 15 do
+			local id = world:component()
+			world:component() -- make the components sparsely interleaved
+			components[i] = id
+		end
+		local e1 = world:entity()
+		for i, id in components do
+			world:set(e1, id, 13 ^ i)
+		end
+
+		local q = world:query(unpack(components))
+
+		for entity, a, b, c, d, e, f, g, h, i, j, k, l, m, n, o in q do
+			CHECK(a == 13 ^ 1)
+			CHECK(b == 13 ^ 2)
+			CHECK(c == 13 ^ 3)
+			CHECK(d == 13 ^ 4)
+			CHECK(e == 13 ^ 5)
+			CHECK(f == 13 ^ 6)
+			CHECK(g == 13 ^ 7)
+			CHECK(h == 13 ^ 8)
+			CHECK(i == 13 ^ 9)
+			CHECK(j == 13 ^ 10)
+			CHECK(k == 13 ^ 11)
+			CHECK(l == 13 ^ 12)
+			CHECK(m == 13 ^ 13)
+			CHECK(n == 13 ^ 14)
+			CHECK(o == 13 ^ 15)
+		end
+	end
+
 	do CASE "should be able to get next results"
 		local world = jecs.world()
 		world:component()
@@ -2044,6 +2315,140 @@ TEST("world:remove()", function()
 end)
 
 TEST("world:set()", function()
+	do CASE "Removing exclusive pair should traverse backwards on edge"
+		local world = jecs.world()
+		local a = world:entity()
+		local b = world:entity()
+		local c = world:entity()
+
+		local BattleLink = world:component()
+		world:add(BattleLink, jecs.Exclusive)
+
+		world:set(a, pair(BattleLink, b), {
+			timestamp = 1,
+			transform = vector.create(1, 2, 3)
+		})
+		world:set(a, pair(BattleLink, c), {
+			timestamp = 2,
+			transform = vector.create(1, 2, 3)
+		})
+
+		CHECK(not world:has(a, pair(BattleLink, b)))
+		CHECK(world:has(a, pair(BattleLink, c)))
+
+		world:remove(a, pair(BattleLink, c))
+
+		CHECK(not world:has(a, pair(BattleLink, b)))
+		CHECK(not world:has(a, pair(BattleLink, c)))
+		CHECK(not world:target(a, BattleLink))
+	end
+
+	do CASE "Exclusive relations"
+		local world = jecs.world()
+		local A = world:component()
+		world:add(A, jecs.Exclusive)
+
+		local B = world:component()
+		local C = world:component()
+
+		local e = world:entity()
+		world:set(e, pair(A, B), true)
+		world:set(e, pair(A, C), true)
+
+		CHECK(world:has(e, pair(A, B)) == false)
+		CHECK(world:has(e, pair(A, C)) == true)
+
+		-- We have to test the path that checks the uncached method
+		local e1 = world:entity()
+
+		world:set(e1, pair(A, B), true)
+		world:set(e1, pair(A, C), true)
+
+		CHECK(world:has(e1, pair(A, B)) == false)
+		CHECK(world:has(e1, pair(A, C)) == true)
+	end
+
+	do CASE "exclusive relations invoke hooks"
+		local world = jecs.world()
+		local A = world:component()
+		local B = world:component()
+		local C = world:component()
+
+		local e_ptr: jecs.Entity = (jecs.Rest :: any) + 1
+
+		world:add(A, jecs.Exclusive)
+		local on_remove_call = false
+		world:set(A, jecs.OnRemove, function(e, id)
+			on_remove_call = true
+		end)
+
+		local on_add_call_count = 0
+		world:set(A, jecs.OnAdd, function(e, id)
+			on_add_call_count += 1
+		end)
+
+
+		local e = world:entity()
+		CHECK(e == e_ptr)
+		world:set(e, pair(A, B))
+		CHECK(on_add_call_count == 1)
+		world:set(e, pair(A, C))
+		CHECK(on_add_call_count == 2)
+		CHECK(on_remove_call)
+
+		CHECK(world:has(e, pair(A, B)) == false)
+		CHECK(world:has(e, pair(A, C)) == true)
+
+		-- We have to ensure that it actually invokes hooks everytime it
+		-- traverses the archetype
+		e = world:entity()
+		world:add(e, pair(A, B))
+		CHECK(on_add_call_count == 3)
+		world:add(e, pair(A, C))
+		CHECK(on_add_call_count == 4)
+		CHECK(on_remove_call)
+
+		CHECK(world:has(e, pair(A, B)) == false)
+		CHECK(world:has(e, pair(A, C)) == true)
+	end
+
+	do CASE "exclusive relations invoke on_remove hooks that should allow side effects"
+		local world = jecs.world()
+		local A = world:component()
+		local B = world:component()
+		local C = world:component()
+		local D = world:component()
+
+		world:add(A, jecs.Exclusive)
+		local call_count = 0
+		world:set(A, jecs.OnRemove, function(e, id)
+			call_count += 1
+			if call_count == 1 then
+				world:set(e, C, true)
+			else
+				world:set(e, D, true)
+			end
+		end)
+
+		local e = world:entity()
+		world:set(e, pair(A, B), true)
+		world:set(e, pair(A, C), true)
+
+		CHECK(world:has(e, pair(A, B)) == false)
+		CHECK(world:has(e, pair(A, C)) == true)
+		CHECK(world:has(e, C))
+
+
+		-- We have to ensure that it actually invokes hooks everytime it
+		-- traverses the archetype
+		e = world:entity()
+		world:set(e, pair(A, B), true)
+		world:set(e, pair(A, C), true)
+
+		CHECK(world:has(e, pair(A, B)) == false)
+		CHECK(world:has(e, pair(A, C)) == true)
+		CHECK(world:has(e, D))
+	end
 	do CASE "archetype move"
 		local world = jecs.world()
 
@@ -2236,7 +2641,7 @@ TEST("#repro2", function()
 	local entity = world:entity()
 	world:set(entity, pair(Lifetime, Particle), 1)
 	world:set(entity, pair(Lifetime, Beam), 2)
-	world:set(entity, pair(4 :: any, 5 :: any), 6) -- noise
+	world:set(entity, pair(world:component(), world:component()), 6) -- noise
 
 	CHECK(world:get(entity, pair(Lifetime, Particle)) == 1)
 	CHECK(world:get(entity, pair(Lifetime, Beam)) == 2)

wally.toml

@@ -1,6 +1,6 @@
 [package]
 name = "ukendio/jecs"
-version = "0.9.0-rc.9"
+version = "0.9.0"
 registry = "https://github.com/UpliftGames/wally-index"
 realm = "shared"
 license = "MIT"