src/graph.luau

@@ -9,17 +9,20 @@ export type Scope = {
     [number]: Scope -- children
 }
 
-export type Node<T> = {
-    scope: Scope,
+export type StartNode<T> = {
     cache: T,
+    [number]: Node<T>
+}
+
+export type Node<T> = StartNode<T> & {
+    scope: Scope,
     effect:  (T) -> (),
-    [number]: Node<T> -- children
 }
 
 -- flag used to detect when node reference capturing is active
 local reff = false
 -- array of all nodes referenced since above flag was set
-local refs = {} :: { Node<unknown> }
+local refs = {} :: { StartNode<unknown> }
 
 local scopes = { n = 0 } :: { [number]: Scope, n: number }
 
@@ -102,7 +105,7 @@ local function run_effect<T>(node: Node<T>)
     node.effect(node.cache)
 end
 
-local function add_child(parent: Node<any>, child: Node<any>)
+local function add_child(parent: StartNode<any>, child: Node<any>)
     table.insert(parent, child)
 end
 
@@ -120,7 +123,7 @@ local function destroy(scope: Scope)
 end
 
 -- runs node effects, recalculates descendants and runs descendant effects
-local function update<T>(node: Node<T>)
+local function update<T>(node: StartNode<T>)
     for _, child in ipairs(node) do
         local scope = child.scope
         assert(scope)
@@ -133,7 +136,7 @@ local function update<T>(node: Node<T>)
 end
 
 -- detect what nodes were referenced in the given callback and returns them in an array
-local function capture<T, U>(fn: (U?) -> T, arg: U?): ({ Node<unknown> }, T)
+local function capture<T, U>(fn: (U?) -> T, arg: U?): ({ StartNode<unknown> }, T)
     if reff then throw("recursive capture detected") end
 
     table.clear(refs)
@@ -164,7 +167,7 @@ local function capture_parents<T, U>(child: Node<T>, fn: (U?) -> T, arg: U?): T
     return result
 end
 
-local function track<T>(node: Node<T>)
+local function track<T>(node: StartNode<T>)
     if reff then table.insert(refs, node :: Node<any>) end
 end
 
@@ -176,13 +179,15 @@ local function create_scope(): Scope
 end
 
 local function create_node<T>(value: T): Node<T>
-    local node = {
+    return {
         scope = create_scope(),
         cache = value,
         effect = function() end,
     }
+end
 
-    return node
+local function create_start_node<T>(value: T): StartNode<T>
+    return { cache = value }
 end
 
 return table.freeze {
@@ -199,6 +204,7 @@ return table.freeze {
     capture = capture,
     capture_parents = capture_parents,
     create_node = create_node,
+    create_start_node = create_start_node,
     create_scope = create_scope,
     refs = refs
 }

src/maps.luau

@@ -6,8 +6,9 @@ local throw = require(script.Parent.throw)
 local flags = require(script.Parent.flags)
 local graph = require(script.Parent.graph)
 type Scope = graph.Scope
-type Node<T> = graph.Node<T>
+type StartNode<T> = graph.StartNode<T>
 local create_node = graph.create_node
+local create_start_node = graph.create_start_node
 local create_scope = graph.create_scope
 local track = graph.track
 local update = graph.update
@@ -38,7 +39,7 @@ local function indexes<K, VI, VO>(input: () -> Map<K, VI>, transform: (() -> VI,
 
     local input_cache = {} :: Map<K, VI>
     local output_cache = {} :: Map<K, VO>
-    local input_nodes = {} :: Map<K, Node<VI>>
+    local input_nodes = {} :: Map<K, StartNode<VI>>
     local remove_queue = {} :: { K }
     local output_array = {} :: { VO }
 
@@ -77,7 +78,7 @@ local function indexes<K, VI, VO>(input: () -> Map<K, VI>, transform: (() -> VI,
 
                     open_scope(scope)
 
-                    local node = create_node(v)
+                    local node = create_start_node(v)
                     input_nodes[i] = node
                     input_cache[i] = v
                     output_cache[i] = transform(function()
@@ -131,7 +132,7 @@ local function values<K, VI, VO>(input: () -> Map<K, VI>, transform: (VI, () ->
     local new_input_cache_up = {} :: Map<VI, K>
 
     local output_cache = {} :: Map<VI, VO>
-    local input_nodes = {} :: Map<VI, Node<K>>
+    local input_nodes = {} :: Map<VI, StartNode<K>>
     local output_array = {} :: { VO }
 
     local scopes = {} :: Map<VI, Scope>
@@ -163,7 +164,7 @@ local function values<K, VI, VO>(input: () -> Map<K, VI>, transform: (VI, () ->
 
                 open_scope(scope)
 
-                local node = create_node(i)
+                local node = create_start_node(i)
                 input_nodes[v] = node
                 output_cache[v] = transform(v, function()
                     track(node)

src/source.luau

@@ -2,7 +2,7 @@ if not game then script = require "test/relative-string" end
 
 local graph = require(script.Parent.graph)
 type Node<T> = graph.Node<T>
-local create_node = graph.create_node
+local create_start_node = graph.create_start_node
 local get_scope = graph.get_scope
 local track = graph.track
 local update = graph.update
@@ -10,9 +10,9 @@ local update = graph.update
 export type Source<T> = (() -> T) & ((T) -> T)
 
 local function source<T>(initial_value: T): Source<T>
-    assert(get_scope())
+    --assert(get_scope())
 
-    local node = create_node(initial_value)
+    local node = create_start_node(initial_value)
 
     return function(...): T
         if select("#", ...) == 0 then -- no args were given

src/spring.luau

@@ -24,7 +24,9 @@ Unsupported datatypes:
 local throw = require(script.Parent.throw)
 local graph = require(script.Parent.graph)
 type Node<T> = graph.Node<T>
+type StartNode<T> = graph.StartNode<T>
 local create_node = graph.create_node
+local create_start_node = graph.create_start_node
 local update = graph.update
 local capture = graph.capture
 local add_child = graph.add_child
@@ -142,7 +144,7 @@ setmetatable(vec6_to_type, invalid_type)
 
 -- maps spring data to its corresponding output node
 -- lifetime of spring data is tied to output node
-local springs: { [SpringData<any>]: Node<any> } = {}
+local springs: { [SpringData<any>]: StartNode<any> } = {}
 setmetatable(springs, { __mode = "v" })
 
 local function spring<T>(source: () -> T, period: number?, damping_ratio: number?): () -> T
@@ -177,8 +179,7 @@ local function spring<T>(source: () -> T, period: number?, damping_ratio: number
         source_value = initial_value,
     }
 
-    local output = create_node(initial_value)
-
+    local output = create_start_node(initial_value)
 
     local updater = create_node(false)
     updater.effect = function()