From 6be2fbb746c14d4a76916e7f5e6e14dd2348d0bc Mon Sep 17 00:00:00 2001
From: richard <56808540+littensy@users.noreply.github.com>
Date: Sat, 25 Jan 2025 11:51:17 -0800
Subject: [PATCH] fix: do not track implicit dependencies in `observe()` and
 `mapped()` (#39)

* fix: use `subscribe` for explicit dependencies

* fix: call listeners initially once

* fix: wrap initial run in `peek()`
---
 src/charm/src/mapped.luau  | 17 ++++++++++++-----
 src/charm/src/observe.luau | 17 ++++++++++-------
 2 files changed, 22 insertions(+), 12 deletions(-)

diff --git a/src/charm/src/mapped.luau b/src/charm/src/mapped.luau
index 1f1e977..555aa3f 100644
--- a/src/charm/src/mapped.luau
+++ b/src/charm/src/mapped.luau
@@ -1,6 +1,6 @@
 local atom = require(script.Parent.atom)
-local effect = require(script.Parent.effect)
 local store = require(script.Parent.store)
+local subscribe = require(script.Parent.subscribe)
 local types = require(script.Parent.types)
 type Atom<T> = types.Atom<T>
 type Selector<T> = types.Selector<T>
@@ -26,13 +26,14 @@ local function mapped<K0, V0, K1, V1>(callback: Selector<{ [K0]: V0 }>, mapper:
 	local prevMappedItems: { [K1]: V1 } = {}
 	local unsubscribe
 
-	unsubscribe = effect(function()
-		if not mappedAtomRef.current then
+	local function listener(items: { [K0]: V0 })
+		local mappedAtom = mappedAtomRef.current
+
+		if not mappedAtom then
 			return unsubscribe()
 		end
 
-		local items = callback()
-		local mappedItems = table.clone(store.peek(mappedAtomRef.current))
+		local mappedItems = table.clone(mappedAtom())
 		local mappedKeys = {}
 
 		-- TODO: Only call mapper if the item has changed.
@@ -56,6 +57,12 @@ local function mapped<K0, V0, K1, V1>(callback: Selector<{ [K0]: V0 }>, mapper:
 
 		prevMappedItems = mappedItems
 		mappedAtom(mappedItems)
+	end
+
+	unsubscribe = subscribe(callback, listener)
+
+	store.peek(function(): ()
+		listener(callback())
 	end)
 
 	return mappedAtom
diff --git a/src/charm/src/observe.luau b/src/charm/src/observe.luau
index 5bb0296..120ae3b 100644
--- a/src/charm/src/observe.luau
+++ b/src/charm/src/observe.luau
@@ -1,4 +1,5 @@
-local effect = require(script.Parent.effect)
+local store = require(script.Parent.store)
+local subscribe = require(script.Parent.subscribe)
 local types = require(script.Parent.types)
 type Selector<T> = types.Selector<T>
 
@@ -16,9 +17,7 @@ local function noop() end
 local function observe<K, V>(callback: Selector<{ [K]: V }>, factory: (value: V, key: K) -> (() -> ())?): () -> ()
 	local connections: { [K]: () -> () } = {}
 
-	local unsubscribe = effect(function()
-		local state = callback()
-
+	local function listener(state: { [K]: V })
 		for key, disconnect in next, connections do
 			if state[key] == nil then
 				connections[key] = nil
@@ -31,17 +30,21 @@ local function observe<K, V>(callback: Selector<{ [K]: V }>, factory: (value: V,
 				connections[key] = factory(value, key) or noop
 			end
 		end
+	end
+
+	local unsubscribe = subscribe(callback, listener)
+
+	store.peek(function(): ()
+		listener(callback())
 	end)
 
-	local function cleanup()
+	return function()
 		unsubscribe()
 		for _, disconnect in next, connections do
 			disconnect()
 		end
 		table.clear(connections)
 	end
-
-	return cleanup
 end
 
 return observe