refactor: use new type solver

.github/workflows/ci.yml

@@ -26,7 +26,7 @@ jobs:
           pnpm prettier --check packages
 
       - name: Run tests
-        run: lute run tests
+        run: lute run test
 
       - name: Build models
         run: lute run build

.lute/check.luau

@@ -16,6 +16,7 @@ local analyze = process.run({
 	"--ignore=**/node_modules/**",
 	"--base-luaurc=.luaurc",
 	"--definitions=roblox.d.luau",
+	"--flag:LuauSolverV2=true",
 	"packages",
 	"tests",
 	"benches",

.lute/test.luau

@@ -0,0 +1 @@
+(require)("../tests/run.server")

README.md

@@ -51,7 +51,7 @@ Charm is a state management library based on [fine-grained reactivity](https://d
     - [`subscribe(getter, callback)`](#subscribegetter-callback)
     - [`untracked(callback)`](#untrackedcallback)
     - [`batch(callback)`](#batchcallback)
-    - [`mapped(getter, mapper)`](#mappedgetter-mapper)
+    - [`mapped(getter, transform)`](#mappedgetter-transform)
     - [`onCleanup(callback, failSilently?)`](#oncleanupcallback-failsilently)
     - [`atom(initialValue, equals?)`](#atominitialvalue-equals)
     - [`trigger(callback)`](#triggercallback)
@@ -472,11 +472,11 @@ end)
 
 ---
 
-### `mapped(getter, mapper)`
+### `mapped(getter, transform)`
 
-The `mapped` function iterates over every key in a table and uses the mapper to assign them to a new key and value. The result is returned as a read-only signal containing the new keys and values. When a key's value changes, or a new key is added to the table, the mapper is called for that key and its current value.
+The `mapped` function iterates over every key in a table and uses the transform function to assign them to a new key and value. The result is returned as a read-only signal containing the new keys and values. When a key's value changes, or a new key is added to the table, `transform` is called for that key and its current value.
 
-The first value returned by the mapper is used as the new value:
+The first value returned by the transform function is used as the new value:
 
 ```luau
 local getList, setList = signal({ "a", "b", "c" })
@@ -488,7 +488,7 @@ end)
 print(getUppercase()) -- { "A", "B", "C" }
 ```
 
-If the mapper returns two values, the second value is used as the new key:
+If the transform function returns two values, the second value is used as the new key:
 
 ```luau
 local getList, setList = signal({ "a", "b", "c" })

package.json

@@ -1,7 +1,7 @@
 {
 	"private": true,
 	"scripts": {
-		"test": "lute run tests",
+		"test": "lute run test",
 		"build": "lute run build",
 		"check": "lute run check",
 		"publish:npm": "pnpm publish -r --access public",

packages/charm-sync/src/client.luau

@@ -3,7 +3,7 @@ local patch = require("./patch")
 local types = require("./types")
 
 type SyncPayload = types.SyncPayload
-type ReactiveProxy<T = {}> = types.ReactiveProxy<T>
+type ReactiveProxy<T = { [any]: any }> = types.ReactiveProxy<T>
 
 local trackedSignals: { [string]: (any) -> any } = {}
 local trackedReactives: { [string]: ReactiveProxy } = {}

packages/charm-sync/src/patch.luau

@@ -39,7 +39,7 @@ end
 	long as the target array is not sparse. This function ensures that the diff
 	function produces a patch that can be correctly applied.
 ]]
-local function stringifySparseArray(object: {}): { [string | number]: any }
+local function stringifySparseArray(object: { [any]: any }): { [string | number]: any }
 	local maxn = table.maxn(object)
 
 	if maxn == 0 or maxn == #object then

packages/charm-sync/src/server.luau

@@ -39,8 +39,9 @@ local syncCallback: ((client: any, payloads: { SyncPayload }) -> ())?
 	support custom implementations of reactive proxies.
 ]]
 local function toRaw<T>(value: T): T
+	local value: any = value
 	if type(value) == "table" and type(value.__target) == "table" and type(value.__track) == "function" then
-		value.__track()
+		(value.__track :: () -> ())()
 		return toRaw(value.__target)
 	end
 	return value
@@ -153,15 +154,17 @@ local function selectFromGlobalPatchList(client: any, globalPatches: { any }): {
 		local status = clientKeys[key]
 
 		if status == LISTENING_FOR_CHANGES then
-			table.insert(payloads, {
+			local payload: SyncPayload = {
 				type = "patch",
 				data = { [key] = patchData },
-			})
+			}
+			table.insert(payloads, payload)
 		elseif status == PENDING_INITIAL_STATE then
-			table.insert(payloads, {
+			local payload: SyncPayload = {
 				type = "init",
 				data = { [key] = update.newValue },
-			})
+			}
+			table.insert(payloads, payload)
 			clientKeys[key] = LISTENING_FOR_CHANGES
 		end
 	end
@@ -228,11 +231,19 @@ local function selectFromGlobalPatch(client: any, globalPatch: { [string]: any }
 	end
 
 	if next(initData) ~= nil then
-		table.insert(payloads, { type = "init", data = initData })
+		local payload: SyncPayload = {
+			type = "init",
+			data = initData,
+		}
+		table.insert(payloads, payload)
 	end
 
 	if next(patchData) ~= nil then
-		table.insert(payloads, { type = "patch", data = patchData })
+		local payload: SyncPayload = {
+			type = "patch",
+			data = patchData,
+		}
+		table.insert(payloads, payload)
 	end
 
 	return payloads

packages/charm-sync/src/utils.luau

@@ -2,10 +2,6 @@ local Charm = require("../Charm")
 
 type Atom<T> = Charm.Atom<T>
 
-type NestedTable = {
-	[any]: NestedTable | any,
-}
-
 --[[
 	Flattens a nested table into a single table with slash-separated keys.
 	Useful for recursively collecting atoms returned by modules.
@@ -13,15 +9,15 @@ type NestedTable = {
 	@param input A nested table.
 	@return A flattened table with slash-separated keys.
 ]]
-local function flatten<Flattened>(input: {}): Flattened
+local function flatten<Flattened>(input: { [any]: any }): Flattened
 	local result = {}
 
-	local function visit(node: {}, path: string)
+	local function visit(node: { [any]: any }, path: string)
 		for key, value in node do
 			local location = if path == "" then tostring(key) else path .. "/" .. tostring(key)
 
 			if type(value) == "table" then
-				visit(value :: {}, location)
+				visit(value, location)
 			else
 				result[location] = value
 			end

packages/charm-sync/src/validate.luau

@@ -1,4 +1,4 @@
-local function isTableUnsafe(object: {})
+local function isTableUnsafe(object: { [any]: any })
 	local key = next(object)
 
 	if key == nil then
@@ -31,9 +31,8 @@ end
 	with remote argument limitations, such as sparse arrays or mixed tables.
 
 	@param value The table value.
-	@param key The key of the value.
 ]]
-local function validate(value: {})
+local function validate(value: { [any]: any })
 	if isTableUnsafe(value) then
 		warn(
 			`Cannot sync tables unsupported by remote events! See the table below for more info.\n\n`

packages/charm-sync/test/patch.test.luau

@@ -2,7 +2,7 @@ local config = require("../src/config")
 local patch = require("../src/patch")
 local test = require("../../../tests/test")
 
-local function mockArraySerdes(object: {}): {}
+local function mockArraySerdes(object: { [any]: any }): { [any]: any }
 	if object[1] then
 		local copy = {}
 		for index = 1, #object do

packages/charm-sync/test/server.test.luau

@@ -4,6 +4,7 @@ local config = require("../src/config")
 local patch = require("../src/patch")
 local server = require("../src/server")
 local test = require("../../../tests/test")
+local types = require("../src/types")
 
 test.afterEach(function()
 	server.reset()
@@ -14,7 +15,7 @@ test("should replicate state changes", function()
 	local a = Charm.atom(0)
 	local b = Charm.atom(0)
 	local c = Charm.atom(0)
-	local target, payloads
+	local target: unknown, payloads: { types.SyncPayload }
 
 	server.addSignalsToClient(client, { a = a, b = b, c = c })
 	server.connect(function(...)
@@ -41,7 +42,7 @@ test("should replicate partial state patches", function()
 	local client = {}
 	local a = Charm.atom({ x = 0, y = 0 })
 	local b = Charm.atom(0 :: number?)
-	local target, payloads
+	local target: unknown, payloads: { types.SyncPayload }
 
 	server.addSignalsToClient(client, { a = a, b = b })
 	server.connect(function(...)
@@ -68,7 +69,7 @@ end)
 test("should replicate partial state patches (reactive)", function()
 	local client = {}
 	local a = DeepCharm.reactive({ x = { y = 0 }, z = 0 :: number? })
-	local target, payloads
+	local target: unknown, payloads: { types.SyncPayload }
 
 	server.addSignalsToClient(client, { a = a })
 	server.connect(function(...)
@@ -118,7 +119,7 @@ test("should init new clients", function()
 	local clientA = {}
 	local clientB = {}
 	local a = Charm.atom(0)
-	local payloadsA, payloadsB
+	local payloadsA: { types.SyncPayload }, payloadsB: { types.SyncPayload }
 
 	server.addSignalsToClient(clientA, { a = a })
 	server.connect(function(target, payloads)
@@ -147,7 +148,7 @@ test("should init new atoms", function()
 	local client = {}
 	local a = Charm.atom(0)
 	local b = Charm.atom(0)
-	local target, payloads
+	local target: unknown, payloads: { types.SyncPayload }
 
 	server.addSignalsToClient(client, { a = a })
 	server.connect(function(...)
@@ -172,7 +173,7 @@ test("should only replicate to synced clients", function()
 	local clientB = {}
 	local a = Charm.atom(0)
 	local b = Charm.atom(0)
-	local payloadsA, payloadsB
+	local payloadsA: { types.SyncPayload }, payloadsB: { types.SyncPayload }
 
 	server.addSignalsToClient(clientA, { a = a })
 	server.addSignalsToClient(clientB, { b = b })
@@ -214,7 +215,7 @@ end)
 test("should serialize state", function()
 	local client = {}
 	local a = Charm.atom({ 1, 2, 3, 4, 5 })
-	local payloads
+	local payloads: { types.SyncPayload }
 
 	server.addSignalsToClient(client, { a = a })
 	server.connect(function(_, p)
@@ -231,7 +232,7 @@ end)
 test("should not send unchanged state", function()
 	local client = {}
 	local a = Charm.atom(0)
-	local payloads
+	local payloads: { types.SyncPayload }
 
 	server.addSignalsToClient(client, { a = a })
 	server.connect(function(_, p)
@@ -262,7 +263,7 @@ test.describe("historical", function()
 		local a = Charm.atom(0)
 		local b = Charm.atom(0)
 		local c = Charm.atom(0)
-		local target, payloads
+		local target: unknown, payloads: { types.SyncPayload }
 
 		server.addSignalsToClient(client, { a = a, b = b, c = c })
 		server.connect(function(...)
@@ -292,7 +293,7 @@ test.describe("historical", function()
 		local a = DeepCharm.reactive({ value = 0 })
 		local b = DeepCharm.reactive({ value = 0 })
 		local c = DeepCharm.reactive({ value = 0 })
-		local target, payloads
+		local target: unknown, payloads: { types.SyncPayload }
 
 		server.addSignalsToClient(client, { a = a, b = b, c = c })
 		server.connect(function(...)
@@ -321,7 +322,7 @@ test.describe("historical", function()
 		local clientA = {}
 		local clientB = {}
 		local a = Charm.atom(0)
-		local payloadsA, payloadsB
+		local payloadsA: { types.SyncPayload }, payloadsB: { types.SyncPayload }
 
 		server.addSignalsToClient(clientA, { a = a })
 		server.connect(function(target, payloads)
@@ -357,7 +358,7 @@ test.describe("historical", function()
 		local client = {}
 		local a = Charm.atom(0)
 		local b = Charm.atom(0)
-		local payloads
+		local payloads: { types.SyncPayload }
 
 		server.addSignalsToClient(client, { a = a })
 		server.connect(function(_, ...)
@@ -386,7 +387,7 @@ test.describe("historical", function()
 	test("should not send unchanged state", function()
 		local client = {}
 		local a = Charm.atom(0)
-		local payloads
+		local payloads: { types.SyncPayload }
 
 		server.addSignalsToClient(client, { a = a })
 		server.connect(function(_, p)

packages/charm-sync/test/utils.test.luau

@@ -8,7 +8,8 @@ test("should flatten functions", function()
 		b = { c = Charm.atom(0) },
 		d = { e = { f = utils.signalToAtom(Charm.signal(0)) } },
 	}
-	local result = utils.flatten(input)
+
+	local result = utils.flatten<<{ [string]: Charm.Atom<number> }>>(input)
 
 	assert(result.a == input.a, "should flatten the first level")
 	assert(result["b/c"] == input.b.c, "should flatten the second level")

packages/charm/src/index.d.ts

@@ -180,11 +180,11 @@ export function batch<Args extends any[], Result>(fn: (...args: Args) => Result,
  * value and the previous value as arguments.
  *
  * @param getter A function that returns the value to watch.
- * @param fn The function to run when the value changes.
+ * @param callback The function to run when the value changes.
  * @returns A function for disposing the effect.
  * @see https://github.com/littensy/charm?tab=readme-ov-file#listengetter-callback
  */
-export function listen<T>(getter: Getter<T>, fn: (value: T, previousValue: T | undefined) => void): Cleanup;
+export function listen<T>(getter: Getter<T>, callback: (value: T, previousValue: T | undefined) => void): Cleanup;
 
 /**
  * Creates an effect that only runs the callback when the value returned by the
@@ -192,34 +192,37 @@ export function listen<T>(getter: Getter<T>, fn: (value: T, previousValue: T | u
  * as arguments.
  *
  * @param getter A function that returns the value to watch.
- * @param fn The function to run when the value changes.
+ * @param callback The function to run when the value changes.
  * @returns A function for disposing the effect.
  * @see https://github.com/littensy/charm?tab=readme-ov-file#subscribegetter-callback
  */
-export function subscribe<T>(getter: Getter<T>, fn: (value: T, previousValue: T) => void): Cleanup;
+export function subscribe<T>(getter: Getter<T>, callback: (value: T, previousValue: T) => void): Cleanup;
 
 /**
  * Creates a new read-only signal that is computed by mapping over the entries
- * of an existing atom. If the key is omitted from the mapper's return value,
+ * of the source table. If the key is omitted from the transform function's
- * the original key is preserved.
+ * return value, the original key is preserved.
  *
- * @param getter Returns the table to map over.
+ * This function is optimized to minimize unnecessary updates by only calling
- * @param mapper Transforms each value-key pair from the source into a new value or value-key pair for the resulting table.
+ * the transform function for entries that have changed since the last run.
- * @see https://github.com/littensy/charm?tab=readme-ov-file#mappedgetter-mapper
+ *
+ * @param getter A signal or function that returns a table
+ * @param transform Function that maps each entry from the source to a new entry in the mapped table
+ * @see https://github.com/littensy/charm?tab=readme-ov-file#mappedgetter-transform
  */
 export function mapped<VI, KI, VO, KO = KI>(
 	getter: Getter<Map<KI, VI> | ReadonlyMap<KI, VI>>,
-	mapper: (value: VI, key: KI) => LuaTuple<[VO, KO]> | VO,
+	transform: (value: VI, key: KI) => LuaTuple<[VO, KO]> | VO,
 ): Getter<ReadonlyMap<KO, VO>>;
 // Overload for arrays
 export function mapped<VI, VO, K extends Key = number>(
 	getter: Getter<readonly VI[]>,
-	mapper: (value: VI, key: number) => LuaTuple<[VO, K]> | VO,
+	transform: (value: VI, key: number) => LuaTuple<[VO, K]> | VO,
 ): Getter<K extends number ? readonly VO[] : { readonly [P in K]: VO }>;
 // Overload for objects
 export function mapped<VI, KI extends Key, VO, KO extends Key = KI>(
 	getter: Getter<{ readonly [K in KI]: VI }>,
-	mapper: (value: VI, key: KI) => LuaTuple<[VO, KO]> | VO,
+	transform: (value: VI, key: KI) => LuaTuple<[VO, KO]> | VO,
 ): Getter<{ readonly [K in KO]: VO }>;
 
 /**
@@ -234,18 +237,18 @@ export function mapped<VI, KI extends Key, VO, KO extends Key = KI>(
  * from the table or when the callback is disposed.
  *
  * @param getter A function that returns the table to observe.
- * @param fn A function that is called for each key in the table.
+ * @param callback A function that is called for each key in the table.
  * @returns A function for disposing the observer.
  * @see https://github.com/littensy/charm?tab=readme-ov-file#observegetter-callback
  */
 export function observe<V, K = number>(
 	getter: Getter<Map<K, V> | ReadonlyMap<K, V> | readonly V[]>,
-	fn: (value: V, key: K) => Cleanup | void,
+	callback: (value: V, key: K) => Cleanup | void,
 ): Cleanup;
 // Overload for objects
 export function observe<V, K extends Key>(
 	getter: Getter<{ readonly [K in Key]: V }>,
-	fn: (value: V, key: K) => Cleanup | void,
+	callback: (value: V, key: K) => Cleanup | void,
 ): Cleanup;
 
 /**

packages/charm/src/init.luau

@@ -96,12 +96,12 @@ local flags = {
 	Wraps a function to prevent yielding when in strict mode. If the function
 	attempts to yield, an error is thrown.
 
-	@param fn The function to wrap.
+	@param callback The function to wrap.
 	@return A wrapped function that cannot yield in strict mode.
 ]]
-local function noYield<Args..., Results...>(fn: (Args...) -> Results...): (Args...) -> Results...
+local function noYield<Args..., Results...>(callback: (Args...) -> Results...): (Args...) -> Results...
 	if not flags.strict then
-		return fn
+		return callback
 	end
 
 	local function noYieldHandler(thread: thread, ok: boolean, ...)
@@ -114,7 +114,7 @@ local function noYield<Args..., Results...>(fn: (Args...) -> Results...): (Args.
 	end
 
 	return function(...)
-		local thread = coroutine.create(fn)
+		local thread = coroutine.create(callback)
 		return noYieldHandler(thread, coroutine.resume(thread, ...))
 	end
 end
@@ -195,7 +195,7 @@ local function runCleanups(cleanups: { Cleanup })
 	end
 
 	if hasErrors then
-		error(`Errors occurred during effect cleanup:\n\n${table.concat(errors, "\n\n")}`, 0)
+		error(`Errors occurred during effect cleanup:\n\n{table.concat(errors, "\n\n")}`, 0)
 	end
 end
 
@@ -206,9 +206,12 @@ end
 	@param effect Effect node to run
 ]]
 local function run(effect: EffectNode)
-	local flags = effect.flags
+	local effectFlags = effect.flags
 
-	if bit32.btest(flags, DIRTY) or (bit32.btest(flags, PENDING) and checkDirty(effect.deps :: Link, effect)) then
+	if
+		bit32.btest(effectFlags, DIRTY)
+		or (bit32.btest(effectFlags, PENDING) and checkDirty(effect.deps :: Link, effect))
+	then
 		runCleanups(effect.cleanups)
 
 		if effect.flags == NONE then
@@ -342,10 +345,10 @@ end
 	inline the operation.
 
 	@param sub Effect or computed node
-	@param flags Subscriber's current flags
+	@param subFlags Subscriber's current flags
 ]]
-local function clearPending(sub: ReactiveNode, flags: ReactiveFlags)
+local function clearPending(sub: ReactiveNode, subFlags: ReactiveFlags)
-	sub.flags = bit32.band(flags, bit32.bnot(PENDING))
+	sub.flags = bit32.band(subFlags, bit32.bnot(PENDING))
 end
 
 --[[
@@ -463,14 +466,14 @@ local function signal<T>(initialValue: T, equals: Equals<T>?): (Getter<T>, Sette
 		deepFreeze(initialValue)
 	end
 
-	local function writeSignal(update: Update<T>): T
+	local function writeSignal(newValue: Update<T>): T
 		local value: T
 
 		-- Determine the new value based on whether the update is a function or
 		-- a direct value
-		if type(update) == "function" then
+		if type(newValue) == "function" then
 			local prevSub = setActiveSub(nil)
-			local success, result = pcall(noYield(update), this.pendingValue)
+			local success, result = pcall(noYield(newValue), this.pendingValue)
 			activeSub = prevSub
 
 			if success then
@@ -479,7 +482,7 @@ local function signal<T>(initialValue: T, equals: Equals<T>?): (Getter<T>, Sette
 				error(result, 2)
 			end
 		else
-			value = update
+			value = newValue
 		end
 
 		-- Check if the new value is different from the pending value
@@ -565,11 +568,14 @@ local function computed<T>(getter: (previousValue: T?) -> T): Getter<T>
 	}
 
 	local function computedOper(): T
-		local flags = this.flags
+		local computedFlags = this.flags
 
 		if
-			bit32.btest(flags, DIRTY)
+			bit32.btest(computedFlags, DIRTY)
-			or (bit32.btest(flags, PENDING) and (checkDirty(this.deps :: Link, this) or clearPending(this, flags)))
+			or (
+				bit32.btest(computedFlags, PENDING)
+				and (checkDirty(this.deps :: Link, this) or clearPending(this, computedFlags))
+			)
 		then
 			if updateComputed(this) then
 				-- Notify subscribers if the value changed
@@ -578,7 +584,7 @@ local function computed<T>(getter: (previousValue: T?) -> T): Getter<T>
 					shallowPropagate(subs)
 				end
 			end
-		elseif flags == NONE then
+		elseif computedFlags == NONE then
 			-- First access should initialize the computed value
 			this.flags = bit32.bor(MUTABLE, RECURSED_CHECK)
 
@@ -694,7 +700,7 @@ end
 	@param fn A signal or function that accesses signals
 	@see https://github.com/littensy/charm?tab=readme-ov-file#triggercallback
 ]]
-local function trigger(fn: () -> ())
+local function trigger(fn: () -> ...any)
 	local sub: ReactiveNode = {
 		flags = WATCHING,
 	}
@@ -707,10 +713,10 @@ local function trigger(fn: () -> ())
 		error(result, 2)
 	end
 
-	local link = sub.deps
+	local currentLink = sub.deps
-	while link do
+	while currentLink do
-		local dep = link.dep
+		local dep = currentLink.dep
-		link = unlink(link, sub)
+		currentLink = unlink(currentLink, sub)
 		local subs = dep.subs
 		if subs then
 			sub.flags = NONE
@@ -808,18 +814,18 @@ end
 	new value and the previous value as arguments.
 
 	@param getter A signal or function that accesses signals
-	@param fn Function to run when the value changes
+	@param callback Function to run when the value changes
 	@return A cleanup function that stops the effect
 	@see https://github.com/littensy/charm?tab=readme-ov-file#listengetter-callback
 ]]
-local function listen<T>(getter: Getter<T>, fn: (state: T, lastState: T?) -> ()): Cleanup
+local function listen<T>(getter: Getter<T>, callback: (state: T, lastState: T?) -> ()): Cleanup
-	local tracked: Getter<T> = if isSignal(getter) then getter else computed(getter)
+	local tracked: Getter<T> = if isSignal(getter) then getter else computed(getter :: (T?) -> T)
 	local current: T
 
 	return effect(function()
 		local previous = current
 		current = tracked()
-		untracked(fn, current, previous)
+		untracked(callback, current, previous)
 	end)
 end
 
@@ -829,12 +835,12 @@ end
 	value as arguments.
 
 	@param getter A signal or function that accesses signals
-	@param fn Function to run when the value changes
+	@param callback Function to run when the value changes
 	@return A cleanup function that stops the effect
 	@see https://github.com/littensy/charm?tab=readme-ov-file#subscribegetter-callback
 ]]
-local function subscribe<T>(getter: Getter<T>, fn: (state: T, lastState: T) -> ()): Cleanup
+local function subscribe<T>(getter: Getter<T>, callback: (state: T, lastState: T) -> ()): Cleanup
-	local tracked: Getter<T> = if isSignal(getter) then getter else computed(getter)
+	local tracked: Getter<T> = if isSignal(getter) then getter else computed(getter :: (T?) -> T)
 	local current: T
 	local firstRun = true
 
@@ -844,7 +850,7 @@ local function subscribe<T>(getter: Getter<T>, fn: (state: T, lastState: T) -> (
 		if firstRun then
 			firstRun = false
 		else
-			untracked(fn, current, previous)
+			untracked(callback, current, previous)
 		end
 	end)
 end
@@ -859,11 +865,11 @@ end
 	during the callback will also be bound to the lifetime of the key.
 
 	@param getter A signal or function that returns a table
-	@param fn Function that is called for each key added to the table
+	@param callback Function that is called for each key added to the table
 	@return A cleanup function that disposes scopes for all keys
 	@see https://github.com/littensy/charm?tab=readme-ov-file#observegetter-callback
 ]]
-local function observe<K, V>(getter: Getter<{ [K]: V }>, fn: (item: V, key: K) -> ...Cleanup?): Cleanup
+local function observe<K, V>(getter: Getter<{ [K]: V }>, callback: (item: V, key: K) -> ...Cleanup?): Cleanup
 	local scopes: { [K]: Cleanup } = {}
 	local stopObserving = false
 
@@ -881,7 +887,7 @@ local function observe<K, V>(getter: Getter<{ [K]: V }>, fn: (item: V, key: K) -
 		for key, value in data do
 			if scopes[key] == nil then
 				local dispose = effectScope(function()
-					return fn(value, key)
+					return callback(value, key)
 				end, true)
 				if stopObserving then
 					dispose()
@@ -911,17 +917,17 @@ end
 
 --[[
 	Creates a new read-only signal that is computed by mapping over the entries
-	of an existing atom. If the key is omitted from the mapper's return value,
+	of the source table. If the key is omitted from the transform function's
-	the original key is preserved.
+	return value, the original key is preserved.
 
 	This function is optimized to minimize unnecessary updates by only calling
-	the mapper for entries that have changed since the last run.
+	the transform function for entries that have changed since the last run.
 
 	@param getter A signal or function that returns a table
-	@param mapper Function that maps each entry from the source to a new entry in the mapped table
+	@param transform Function that maps each entry from the source to a new entry in the mapped table
-	@see https://github.com/littensy/charm?tab=readme-ov-file#mappedgetter-mapper
+	@see https://github.com/littensy/charm?tab=readme-ov-file#mappedgetter-transform
 ]]
-local function mapped<KI, VI, KO, VO>(getter: Getter<{ [KI]: VI }>, mapper: (VI, KI) -> (VO, KO)): Getter<{ [KO]: VO }>
+local function mapped<KI, VI, KO, VO>(getter: Getter<{ [KI]: VI }>, transform: (VI, KI) -> (VO, KO)): Getter<{ [KO]: VO }>
 	local nextInput: { [KI]: VI } = {}
 	local keyMap: { [KI]: KO } = {}
 
@@ -957,7 +963,7 @@ local function mapped<KI, VI, KO, VO>(getter: Getter<{ [KI]: VI }>, mapper: (VI,
 				continue
 			end
 
-			local nextValueOut, keyOutOrNil = mapper(nextValueIn, keyIn)
+			local nextValueOut, keyOutOrNil = transform(nextValueIn, keyIn)
 			local nextKeyOut: KO = if keyOutOrNil ~= nil then keyOutOrNil else keyIn :: any
 			local prevKeyOut = keyMap[keyIn]
 
@@ -999,8 +1005,8 @@ return {
 	observe = observe,
 	mapped = mapped :: (<KI, VI, KO, VO>(
 		getter: Getter<{ [KI]: VI }>,
-		mapper: (VI, KI) -> (VO, KO)
+		transform: (VI, KI) -> (VO, KO)
-	) -> Getter<{ [KO]: VO }>) & (<K, VI, VO>(getter: Getter<{ [K]: VI }>, mapper: (VI, K) -> VO) -> Getter<{ [K]: VO }>),
+	) -> Getter<{ [KO]: VO }>) & (<K, VI, VO>(getter: Getter<{ [K]: VI }>, transform: (VI, K) -> VO) -> Getter<{ [K]: VO }>),
 	onCleanup = onCleanup,
 	getActiveSub = getActiveSub,
 	setActiveSub = setActiveSub,

packages/charm/test/computed.test.luau

@@ -84,7 +84,7 @@ end)
 test("should receive previous value", function()
 	local calls = {}
 	local src, setSrc = signal(0)
-	local c1 = computed(function(current): number
+	local c1 = computed(function(current: number?): number
 		local incoming = src()
 		return if current == incoming or incoming % 2 == 1 then current or incoming else incoming
 	end)
@@ -192,10 +192,10 @@ test("should trigger effect even computed already dirty", function()
 		table.insert(calls, c2())
 	end)
 	assert(table.concat(calls, ",") == "0foo", table.concat(calls, ","))
-	assert(v() == 1, v())
+	assert(v() == 1, `expected 1 for v(), got {v()}`)
 	v(2)
 	assert(table.concat(calls, ",") == "0foo,2foo", table.concat(calls, ","))
-	assert(v() == 2, v())
+	assert(v() == 2, `expected 2 for v(), got {v()}`)
 end)
 
 return {}

packages/charm/test/effect.test.luau

@@ -440,7 +440,7 @@ end)
 test("should run the cleanup if the effect disposes itself", function()
 	local a, setA = signal(0)
 	local calls = 0
-	local dispose
+	local dispose: () -> ()
 
 	dispose = effect(function()
 		if a() > 0 then
@@ -460,7 +460,7 @@ end)
 test("should not run the effect if the cleanup function disposes it", function()
 	local a, setA = signal(0)
 	local calls = 0
-	local dispose
+	local dispose: () -> ()
 
 	dispose = effect(function()
 		a()

packages/charm/test/effectScope.test.luau

@@ -31,8 +31,8 @@ end)
 
 test("should run indirect scope cleanup", function()
 	local cleanups = 0
+	local cleanup: () -> ()
 
-	local cleanup
 	local stopScope = effectScope(function()
 		cleanup = effectScope(function()
 			onCleanup(function()
@@ -50,8 +50,8 @@ end)
 
 test("should run indirect effect cleanup", function()
 	local cleanups = 0
-
 	local a, setA = signal(false)
+
 	local stopScope = effectScope(function()
 		effect(function()
 			a()
@@ -73,7 +73,7 @@ end)
 test("should dispose inner effects if created in an effect", function()
 	local source, setSource = signal(1)
 	local triggers = 0
-	local dispose
+	local dispose: () -> ()
 
 	effect(function()
 		dispose = effectScope(function()

packages/charm/test/gc.test.luau

@@ -26,7 +26,7 @@ end
 	immediately closing it, causing alien-signals to unlink the computed value
 	from its dependencies and allow it to be garbage collected.
 ]]
-local function unlink(getter: () -> ())
+local function unlink(getter: () -> unknown)
 	effectScope(function()
 		getter()
 	end)()

packages/charm/test/observe.test.luau

@@ -95,7 +95,7 @@ test("should handle recursive additions and removals", function()
 
 	observe(items, function(item)
 		if item < 5 then
-			setItems(function(state)
+			setItems(function(state: { number })
 				state = table.clone(state)
 				table.insert(state, item + 1)
 				return state
@@ -117,7 +117,7 @@ test("should handle self removal", function()
 	local edits = {}
 
 	observe(items, function(item, index)
-		setItems(function(state)
+		setItems(function(state: { number })
 			state = table.clone(state)
 			state[index] = nil
 			return state
@@ -134,7 +134,7 @@ end)
 test("should allow disposal during addition", function()
 	local items, setItems = signal({})
 	local edits = {}
-	local dispose
+	local dispose: () -> ()
 
 	dispose = observe(items, function(item)
 		if item == 1 then
@@ -153,7 +153,7 @@ end)
 test("should allow disposal during removal", function()
 	local items, setItems = signal({ 1, 2, 3, 4 })
 	local edits = {}
-	local dispose
+	local dispose: () -> ()
 
 	dispose = observe(items, function(item)
 		table.insert(edits, `+{item}`)

packages/charm/test/signal.test.luau

@@ -6,7 +6,7 @@ local effect = Charm.effect
 
 test("should accept equality function", function()
 	local calls = {}
-	local src, setSrc = signal(0, function(current, incoming)
+	local src, setSrc = signal(0, function(current: number, incoming: number)
 		return current == incoming or incoming % 2 == 1
 	end)
 

packages/charm/test/topology.test.luau

@@ -442,18 +442,16 @@ end)
 test.describe("error handling", function()
 	test("should keep graph consistent on errors during activation", function()
 		local a = atom(0)
-		local b = computed(function()
+		local b = computed(function(): nil
 			error("fail")
 		end)
 		local c = computed(function()
 			return a()
 		end)
 
-		local success, result = pcall(function()
+		local success, result = pcall(b)
-			b()
-		end)
 		assert(not success, "should throw")
-		assert(string.match(result, "fail"), "should throw fail")
+		assert(string.match(tostring(result), "fail"), "should throw fail")
 
 		a(1)
 		assert(c() == 1, "c should recover and return 1")
@@ -461,7 +459,7 @@ test.describe("error handling", function()
 
 	test("should keep graph consistent on errors in computeds", function()
 		local a = atom(0)
-		local b = computed(function()
+		local b = computed(function(): number
 			if a() == 1 then
 				error("fail")
 			end
@@ -474,11 +472,9 @@ test.describe("error handling", function()
 		assert(c() == 0, "c should be 0")
 
 		a(1)
-		local success, result = pcall(function()
+		local success, result = pcall(b)
-			b()
-		end)
 		assert(not success, "should throw")
-		assert(string.match(result, "fail"), "should throw fail")
+		assert(string.match(tostring(result), "fail"), "should throw fail")
 
 		a(2)
 		assert(c() == 2, "c should recover and return 2")

packages/charm/test/untracked.test.luau

@@ -38,7 +38,7 @@ end)
 
 test("should run detached from effect scope", function()
 	local effects = 0
-	local stopEffect
+	local stopEffect: () -> ()
 
 	local stopScope = effectScope(function()
 		untracked(function()

packages/deep-charm/test/reactive.test.luau

@@ -49,10 +49,10 @@ test("should unwrap proxy assignments", function()
 	end)
 
 	src.a, src.b = src.a, src.b
-	assert(runs == 1, runs)
+	assert(runs == 1, `bad runs: {runs}`)
 
 	src.a, src.b = src.b, src.a
-	assert(runs == 3, runs)
+	assert(runs == 3, `bad runs: {runs}`)
 end)
 
 test("should track iteration", function()
@@ -125,10 +125,10 @@ test("should not track unread properties", function()
 		local _ = src.value.a
 		calls += 1
 	end)
-	assert(calls == 1, calls)
+	assert(calls == 1, `bad calls: {calls}`)
 
 	src.value.b = 3
-	assert(calls == 1, calls)
+	assert(calls == 1, `bad calls: {calls}`)
 end)
 
 test("should overwrite with table passed to setter", function()
@@ -159,10 +159,10 @@ test("should unwrap proxy", function()
 
 	assert(toRaw(src) == raw, "unwrap did not return the original table")
 	assert(toRaw(raw) == raw, "unwrap modified a non-proxy value")
-	assert(runs == 1, runs)
+	assert(runs == 1, `bad runs: {runs}`)
 
 	src.x = 1
-	assert(runs == 2, runs)
+	assert(runs == 2, `bad runs: {runs}`)
 end)
 
 test("should unwrap nested proxy", function()
@@ -177,13 +177,13 @@ test("should unwrap nested proxy", function()
 	end)
 
 	assert(toRaw(src) == raw, "unwrap did not return the original table")
-	assert(runs == 1, runs)
+	assert(runs == 1, `bad runs: {runs}`)
 
 	inner.x = 1
-	assert(runs == 2, runs)
+	assert(runs == 2, `bad runs: {runs}`)
 
 	src.y = 2
-	assert(runs == 3, runs)
+	assert(runs == 3, `bad runs: {runs}`)
 end)
 
 return {}

packages/react-charm/src/init.luau

@@ -13,12 +13,12 @@ local React = require("./React")
 	@param dependencies An array of values used to memoize the getter.
 	@return The current state.
 ]]
-local function useSignalState<T>(getter: () -> T, dependencies: { any }?): T
+local function useSignalState<T>(getter: () -> T, dependencies: {}?): T
 	local value, setValue = React.useState(getter)
 
 	React.useLayoutEffect(function()
-		return Charm.listen(getter, setValue)
+		return Charm.listen(getter, setValue :: (T, T?) -> ())
-	end, dependencies or {})
+	end, dependencies :: { any } or {})
 
 	return value
 end
@@ -34,13 +34,13 @@ end
 	@param dependencies An array of values used to memoize the getter.
 	@return A binding that stores the current state.
 ]]
-local function useSignalBinding<T>(getter: () -> T, dependencies: { any }?)
+local function useSignalBinding<T>(getter: () -> T, dependencies: {}?)
 	local initialValue = React.useMemo(getter, {})
 	local binding, setBinding = React.useBinding(initialValue)
 
 	React.useLayoutEffect(function()
-		return Charm.listen(getter, setBinding)
+		return Charm.listen(getter, setBinding :: (T, T?) -> ())
-	end, dependencies or {})
+	end, dependencies :: { any } or {})
 
 	return binding
 end

packages/react-charm/test/helpers/renderHook.luau

@@ -13,12 +13,13 @@ local function renderHook<Props, Result>(callback: (Props) -> Result, props: Pro
 
 	local function Component(props: Props)
 		hook.result = callback(props)
+		return nil
 	end
 
 	function hook.rerender(newProps: Props?)
 		props = newProps or props
 		ReactRoblox.act(function()
-			root:render(React.createElement(Component, props))
+			root:render(React.createElement(Component, props) :: any)
 		end)
 	end
 

packages/react-charm/test/init.luau

@@ -1,5 +1,6 @@
 local test = require("../../tests/test")
 
+-- selene: allow(global_usage)
 _G.__ROACT_17_MOCK_SCHEDULER__ = true
 
 test.describe("useSignalState", function()

packages/vide-charm/src/init.luau

@@ -11,7 +11,7 @@ local Vide = require("./Vide")
 local function useSignalState<State>(getter: () -> State): () -> State
 	local state = Vide.source(getter())
 
-	Vide.cleanup(Charm.listen(getter, state))
+	Vide.cleanup(Charm.listen(getter, state :: (State, State?) -> ()))
 
 	return state
 end

packages/vide-charm/test/useSignalState.test.luau

@@ -5,7 +5,7 @@ local test = require("../../../tests/test")
 
 test("tracks signal state", function()
 	local getState, setState = Charm.signal(0)
-	local source
+	local source: () -> number
 	local cleanup = Vide.root(function()
 		source = VideCharm.useSignalState(getState)
 	end)
@@ -17,7 +17,7 @@ end)
 
 test("accepts a selector", function()
 	local getState, setState = Charm.signal(0)
-	local source
+	local source: () -> number
 	local cleanup = Vide.root(function()
 		source = VideCharm.useSignalState(function()
 			return 2 * getState()

selene.toml

@@ -2,6 +2,4 @@ std = "roblox"
 exclude = ["*/node_modules/*"]
 
 [lints]
-global_usage = "allow"
 shadowing = "allow"
-incorrect_standard_library_use = "allow"

tests/init.luau

@@ -1 +0,0 @@
-(require)("@self/run.server")