Renamed Val to Cell.

core/src/commonMain/kotlin/world/phantasmal/core/disposable/DisposableCreation.kt

@@ -1,6 +1,6 @@
 package world.phantasmal.core.disposable
 
-private object StubDisposable : Disposable {
+private object NopDisposable : Disposable {
     override fun dispose() {
         // Do nothing.
     }
@@ -8,4 +8,7 @@ private object StubDisposable : Disposable {
 
 fun disposable(dispose: () -> Unit): Disposable = SimpleDisposable(dispose)
 
-fun stubDisposable(): Disposable = StubDisposable
+/**
+ * Returns a disposable that does nothing when disposed.
+ */
+fun nopDisposable(): Disposable = NopDisposable

core/src/commonMain/kotlin/world/phantasmal/core/unsafe/UnsafeCast.kt

@@ -1,7 +1,14 @@
 package world.phantasmal.core.unsafe
 
+/**
+ * Asserts that receiver is of type T. No runtime check happens in KJS. Should only be used when
+ * absolutely certain that receiver is indeed a T.
+ */
+expect inline fun <T> Any?.unsafeCast(): T
+
 /**
  * Asserts that T is not null. No runtime check happens in KJS. Should only be used when absolutely
  * certain that T is indeed not null.
  */
-expect inline fun <T> T?.unsafeAssertNotNull(): T
+@Suppress("NOTHING_TO_INLINE")
+inline fun <T> T?.unsafeAssertNotNull(): T = unsafeCast()

core/src/jsMain/kotlin/world/phantasmal/core/unsafe/UnsafeCast.kt

@@ -1,4 +1,6 @@
 package world.phantasmal.core.unsafe
 
+import kotlin.js.unsafeCast as kotlinUnsafeCast
+
 @Suppress("NOTHING_TO_INLINE")
-actual inline fun <T> T?.unsafeAssertNotNull(): T = unsafeCast<T>()
+actual inline fun <T> Any?.unsafeCast(): T = kotlinUnsafeCast<T>()

core/src/jvmMain/kotlin/world/phantasmal/core/unsafe/UnsafeCast.kt

@@ -1,4 +1,4 @@
 package world.phantasmal.core.unsafe
 
 @Suppress("UNCHECKED_CAST", "NOTHING_TO_INLINE")
-actual inline fun <T> T?.unsafeAssertNotNull(): T = this as T
+actual inline fun <T> Any?.unsafeCast(): T = this as T

observable/src/commonMain/kotlin/world/phantasmal/observable/cell/AbstractCell.kt

@@ -1,11 +1,11 @@
-package world.phantasmal.observable.value
+package world.phantasmal.observable.cell
 
 import world.phantasmal.core.disposable.Disposable
 import world.phantasmal.core.disposable.disposable
 import world.phantasmal.observable.ChangeEvent
 import world.phantasmal.observable.Observer
 
-abstract class AbstractVal<T> : Val<T> {
+abstract class AbstractCell<T> : Cell<T> {
     protected val observers: MutableList<Observer<T>> = mutableListOf()
 
     final override fun observe(observer: Observer<T>): Disposable =

observable/src/commonMain/kotlin/world/phantasmal/observable/cell/AbstractDependentCell.kt

@@ -1,18 +1,18 @@
-package world.phantasmal.observable.value
+package world.phantasmal.observable.cell
 
 import world.phantasmal.core.disposable.Disposable
 import world.phantasmal.core.disposable.disposable
-import world.phantasmal.core.unsafe.unsafeAssertNotNull
+import world.phantasmal.core.unsafe.unsafeCast
 import world.phantasmal.observable.Observer
 
 /**
- * Starts observing its dependencies when the first observer on this val is registered. Stops
+ * Starts observing its dependencies when the first observer on this cell is registered. Stops
- * observing its dependencies when the last observer on this val is disposed. This way no extra
+ * observing its dependencies when the last observer ov this cell is disposed. This way no extra
  * disposables need to be managed when e.g. [map] is used.
  */
-abstract class AbstractDependentVal<T>(
+abstract class AbstractDependentCell<T>(
-    private vararg val dependencies: Val<*>,
+    private vararg val dependencies: Cell<*>,
-) : AbstractVal<T>() {
+) : AbstractCell<T>() {
     /**
      * Is either empty or has a disposable per dependency.
      */
@@ -31,7 +31,7 @@ abstract class AbstractDependentVal<T>(
                 _value = computeValue()
             }
 
-            return _value.unsafeAssertNotNull()
+            return _value.unsafeCast()
         }
 
     override fun observe(callNow: Boolean, observer: Observer<T>): Disposable {

observable/src/commonMain/kotlin/world/phantasmal/observable/cell/Cell.kt

@@ -0,0 +1,51 @@
+package world.phantasmal.observable.cell
+
+import world.phantasmal.core.disposable.Disposable
+import world.phantasmal.observable.Observable
+import world.phantasmal.observable.Observer
+import world.phantasmal.observable.cell.list.DependentListCell
+import world.phantasmal.observable.cell.list.ListCell
+import kotlin.reflect.KProperty
+
+/**
+ * An observable with the notion of a current [value].
+ */
+interface Cell<out T> : Observable<T> {
+    val value: T
+
+    operator fun getValue(thisRef: Any?, property: KProperty<*>): T = value
+
+    /**
+     * @param callNow Call [observer] immediately with the current [mutableCell].
+     */
+    fun observe(callNow: Boolean = false, observer: Observer<T>): Disposable
+
+    /**
+     * Map a transformation function over this cell.
+     *
+     * @param transform called whenever this cell changes
+     */
+    fun <R> map(transform: (T) -> R): Cell<R> =
+        DependentCell(this) { transform(value) }
+
+    fun <R> mapToList(transform: (T) -> List<R>): ListCell<R> =
+        DependentListCell(this) { transform(value) }
+
+    /**
+     * Map a transformation function that returns a cell over this cell. The resulting cell will
+     * change when this cell changes and when the cell returned by [transform] changes.
+     *
+     * @param transform called whenever this cell changes
+     */
+    fun <R> flatMap(transform: (T) -> Cell<R>): Cell<R> =
+        FlatteningDependentCell(this) { transform(value) }
+
+    fun <R> flatMapNull(transform: (T) -> Cell<R>?): Cell<R?> =
+        FlatteningDependentCell(this) { transform(value) ?: nullCell() }
+
+    fun isNull(): Cell<Boolean> =
+        map { it == null }
+
+    fun isNotNull(): Cell<Boolean> =
+        map { it != null }
+}

observable/src/commonMain/kotlin/world/phantasmal/observable/cell/CellCreation.kt

@@ -0,0 +1,72 @@
+package world.phantasmal.observable.cell
+
+private val TRUE_CELL: Cell<Boolean> = StaticCell(true)
+private val FALSE_CELL: Cell<Boolean> = StaticCell(false)
+private val NULL_CELL: Cell<Nothing?> = StaticCell(null)
+private val ZERO_INT_CELL: Cell<Int> = StaticCell(0)
+private val EMPTY_STRING_CELL: Cell<String> = StaticCell("")
+
+fun <T> cell(value: T): Cell<T> = StaticCell(value)
+
+fun trueCell(): Cell<Boolean> = TRUE_CELL
+
+fun falseCell(): Cell<Boolean> = FALSE_CELL
+
+fun nullCell(): Cell<Nothing?> = NULL_CELL
+
+fun zeroIntCell(): Cell<Int> = ZERO_INT_CELL
+
+fun emptyStringCell(): Cell<String> = EMPTY_STRING_CELL
+
+/**
+ * Creates a [MutableCell] with initial value [value].
+ */
+fun <T> mutableCell(value: T): MutableCell<T> = SimpleCell(value)
+
+/**
+ * Creates a [MutableCell] which calls [getter] or [setter] when its value is being read or written
+ * to, respectively.
+ */
+fun <T> mutableCell(getter: () -> T, setter: (T) -> Unit): MutableCell<T> =
+    DelegatingCell(getter, setter)
+
+/**
+ * Map a transformation function over 2 cells.
+ *
+ * @param transform called whenever [c1] or [c2] changes
+ */
+fun <T1, T2, R> map(
+    c1: Cell<T1>,
+    c2: Cell<T2>,
+    transform: (T1, T2) -> R,
+): Cell<R> =
+    DependentCell(c1, c2) { transform(c1.value, c2.value) }
+
+/**
+ * Map a transformation function over 3 cells.
+ *
+ * @param transform called whenever [c1], [c2] or [c3] changes
+ */
+fun <T1, T2, T3, R> map(
+    c1: Cell<T1>,
+    c2: Cell<T2>,
+    c3: Cell<T3>,
+    transform: (T1, T2, T3) -> R,
+): Cell<R> =
+    DependentCell(c1, c2, c3) { transform(c1.value, c2.value, c3.value) }
+
+/**
+ * Map a transformation function that returns a cell over 2 cells. The resulting cell will change
+ * when either cell changes and also when the cell returned by [transform] changes.
+ *
+ * @param transform called whenever this cell changes
+ */
+fun <T1, T2, R> flatMap(
+    c1: Cell<T1>,
+    c2: Cell<T2>,
+    transform: (T1, T2) -> Cell<R>,
+): Cell<R> =
+    FlatteningDependentCell(c1, c2) { transform(c1.value, c2.value) }
+
+fun and(vararg cells: Cell<Boolean>): Cell<Boolean> =
+    DependentCell(*cells) { cells.all { it.value } }

observable/src/commonMain/kotlin/world/phantasmal/observable/cell/CellExtensions.kt

@@ -0,0 +1,61 @@
+package world.phantasmal.observable.cell
+
+infix fun <T> Cell<T>.eq(value: T): Cell<Boolean> =
+    map { it == value }
+
+infix fun <T> Cell<T>.eq(other: Cell<T>): Cell<Boolean> =
+    map(this, other) { a, b -> a == b }
+
+infix fun <T> Cell<T>.ne(value: T): Cell<Boolean> =
+    map { it != value }
+
+infix fun <T> Cell<T>.ne(other: Cell<T>): Cell<Boolean> =
+    map(this, other) { a, b -> a != b }
+
+fun <T> Cell<T?>.orElse(defaultValue: () -> T): Cell<T> =
+    map { it ?: defaultValue() }
+
+infix fun <T : Comparable<T>> Cell<T>.gt(value: T): Cell<Boolean> =
+    map { it > value }
+
+infix fun <T : Comparable<T>> Cell<T>.gt(other: Cell<T>): Cell<Boolean> =
+    map(this, other) { a, b -> a > b }
+
+infix fun <T : Comparable<T>> Cell<T>.lt(value: T): Cell<Boolean> =
+    map { it < value }
+
+infix fun <T : Comparable<T>> Cell<T>.lt(other: Cell<T>): Cell<Boolean> =
+    map(this, other) { a, b -> a < b }
+
+infix fun Cell<Boolean>.and(other: Cell<Boolean>): Cell<Boolean> =
+    map(this, other) { a, b -> a && b }
+
+infix fun Cell<Boolean>.and(other: Boolean): Cell<Boolean> =
+    if (other) this else falseCell()
+
+infix fun Cell<Boolean>.or(other: Cell<Boolean>): Cell<Boolean> =
+    map(this, other) { a, b -> a || b }
+
+infix fun Cell<Boolean>.xor(other: Cell<Boolean>): Cell<Boolean> =
+    // Use != because of https://youtrack.jetbrains.com/issue/KT-31277.
+    map(this, other) { a, b -> a != b }
+
+operator fun Cell<Boolean>.not(): Cell<Boolean> = map { !it }
+
+operator fun Cell<Int>.plus(value: Int): Cell<Int> =
+    map { it + value }
+
+operator fun Cell<Int>.minus(value: Int): Cell<Int> =
+    map { it - value }
+
+fun Cell<String>.isEmpty(): Cell<Boolean> =
+    map { it.isEmpty() }
+
+fun Cell<String>.isNotEmpty(): Cell<Boolean> =
+    map { it.isNotEmpty() }
+
+fun Cell<String>.isBlank(): Cell<Boolean> =
+    map { it.isBlank() }
+
+fun Cell<String>.isNotBlank(): Cell<Boolean> =
+    map { it.isNotBlank() }

observable/src/commonMain/kotlin/world/phantasmal/observable/cell/DelegatingCell.kt

@@ -1,9 +1,9 @@
-package world.phantasmal.observable.value
+package world.phantasmal.observable.cell
 
-class DelegatingVal<T>(
+class DelegatingCell<T>(
     private val getter: () -> T,
     private val setter: (T) -> Unit,
-) : AbstractVal<T>(), MutableVal<T> {
+) : AbstractCell<T>(), MutableCell<T> {
     override var value: T
         get() = getter()
         set(value) {

observable/src/commonMain/kotlin/world/phantasmal/observable/cell/DependentCell.kt

@@ -0,0 +1,11 @@
+package world.phantasmal.observable.cell
+
+/**
+ * Cell of which the value depends on 0 or more other cells.
+ */
+class DependentCell<T>(
+    vararg dependencies: Cell<*>,
+    private val compute: () -> T,
+) : AbstractDependentCell<T>(*dependencies) {
+    override fun computeValue(): T = compute()
+}

observable/src/commonMain/kotlin/world/phantasmal/observable/cell/FlatteningDependentCell.kt

@@ -1,4 +1,4 @@
-package world.phantasmal.observable.value
+package world.phantasmal.observable.cell
 
 import world.phantasmal.core.disposable.Disposable
 import world.phantasmal.core.disposable.disposable
@@ -6,19 +6,19 @@ import world.phantasmal.core.unsafe.unsafeAssertNotNull
 import world.phantasmal.observable.Observer
 
 /**
- * Similar to [DependentVal], except that this val's [compute] returns a val.
+ * Similar to [DependentCell], except that this cell's [compute] returns a cell.
  */
-class FlatteningDependentVal<T>(
+class FlatteningDependentCell<T>(
-    vararg dependencies: Val<*>,
+    vararg dependencies: Cell<*>,
-    private val compute: () -> Val<T>,
+    private val compute: () -> Cell<T>,
-) : AbstractDependentVal<T>(*dependencies) {
+) : AbstractDependentCell<T>(*dependencies) {
-    private var computedVal: Val<T>? = null
+    private var computedCell: Cell<T>? = null
-    private var computedValObserver: Disposable? = null
+    private var computedCellObserver: Disposable? = null
 
     override val value: T
         get() {
             return if (hasObservers) {
-                computedVal.unsafeAssertNotNull().value
+                computedCell.unsafeAssertNotNull().value
             } else {
                 super.value
             }
@@ -31,26 +31,26 @@ class FlatteningDependentVal<T>(
             superDisposable.dispose()
 
             if (!hasObservers) {
-                computedValObserver?.dispose()
+                computedCellObserver?.dispose()
-                computedValObserver = null
+                computedCellObserver = null
-                computedVal = null
+                computedCell = null
             }
         }
     }
 
     override fun computeValue(): T {
-        val computedVal = compute()
+        val computedCell = compute()
-        this.computedVal = computedVal
+        this.computedCell = computedCell
 
-        computedValObserver?.dispose()
+        computedCellObserver?.dispose()
 
         if (hasObservers) {
-            computedValObserver = computedVal.observe { (value) ->
+            computedCellObserver = computedCell.observe { (value) ->
                 _value = value
                 emit()
             }
         }
 
-        return computedVal.value
+        return computedCell.value
     }
 }

observable/src/commonMain/kotlin/world/phantasmal/observable/cell/MutableCell.kt

@@ -1,8 +1,8 @@
-package world.phantasmal.observable.value
+package world.phantasmal.observable.cell
 
 import kotlin.reflect.KProperty
 
-interface MutableVal<T> : Val<T> {
+interface MutableCell<T> : Cell<T> {
     override var value: T
 
     operator fun setValue(thisRef: Any?, property: KProperty<*>, value: T) {

observable/src/commonMain/kotlin/world/phantasmal/observable/cell/SimpleCell.kt

@@ -1,6 +1,6 @@
-package world.phantasmal.observable.value
+package world.phantasmal.observable.cell
 
-class SimpleVal<T>(value: T) : AbstractVal<T>(), MutableVal<T> {
+class SimpleCell<T>(value: T) : AbstractCell<T>(), MutableCell<T> {
     override var value: T = value
         set(value) {
             if (value != field) {

observable/src/commonMain/kotlin/world/phantasmal/observable/cell/StaticCell.kt

@@ -1,18 +1,18 @@
-package world.phantasmal.observable.value
+package world.phantasmal.observable.cell
 
 import world.phantasmal.core.disposable.Disposable
-import world.phantasmal.core.disposable.stubDisposable
+import world.phantasmal.core.disposable.nopDisposable
 import world.phantasmal.observable.ChangeEvent
 import world.phantasmal.observable.Observer
 
-class StaticVal<T>(override val value: T) : Val<T> {
+class StaticCell<T>(override val value: T) : Cell<T> {
     override fun observe(callNow: Boolean, observer: Observer<T>): Disposable {
         if (callNow) {
             observer(ChangeEvent(value))
         }
 
-        return stubDisposable()
+        return nopDisposable()
     }
 
-    override fun observe(observer: Observer<T>): Disposable = stubDisposable()
+    override fun observe(observer: Observer<T>): Disposable = nopDisposable()
 }

observable/src/commonMain/kotlin/world/phantasmal/observable/cell/list/AbstractDependentListCell.kt

@@ -1,20 +1,20 @@
-package world.phantasmal.observable.value.list
+package world.phantasmal.observable.cell.list
 
 import world.phantasmal.core.disposable.Disposable
 import world.phantasmal.core.disposable.disposable
 import world.phantasmal.observable.Observer
-import world.phantasmal.observable.value.AbstractVal
+import world.phantasmal.observable.cell.AbstractCell
-import world.phantasmal.observable.value.Val
+import world.phantasmal.observable.cell.Cell
 
 /**
- * Starts observing its dependencies when the first observer on this property is registered.
+ * Starts observing its dependencies when the first observer on this cell is registered. Stops
- * Stops observing its dependencies when the last observer on this property is disposed.
+ * observing its dependencies when the last observer on this cell is disposed. This way no extra
- * This way no extra disposables need to be managed when e.g. [map] is used.
+ * disposables need to be managed when e.g. [map] is used.
  */
-abstract class AbstractDependentListVal<E>(
+abstract class AbstractDependentListCell<E>(
-    private vararg val dependencies: Val<*>,
+    private vararg val dependencies: Cell<*>,
-) : AbstractListVal<E>(extractObservables = null) {
+) : AbstractListCell<E>(extractObservables = null) {
-    private val _sizeVal = SizeVal()
+    private val _size = SizeCell()
 
     /**
      * Is either empty or has a disposable per dependency.
@@ -37,7 +37,7 @@ abstract class AbstractDependentListVal<E>(
             return elements
         }
 
-    override val size: Val<Int> = _sizeVal
+    override val size: Cell<Int> = _size
 
     override fun observe(callNow: Boolean, observer: Observer<List<E>>): Disposable {
         initDependencyObservers()
@@ -50,7 +50,7 @@ abstract class AbstractDependentListVal<E>(
         }
     }
 
-    override fun observeList(callNow: Boolean, observer: ListValObserver<E>): Disposable {
+    override fun observeList(callNow: Boolean, observer: ListObserver<E>): Disposable {
         initDependencyObservers()
 
         val superDisposable = super.observeList(callNow, observer)
@@ -87,7 +87,7 @@ abstract class AbstractDependentListVal<E>(
     }
 
     private fun disposeDependencyObservers() {
-        if (observers.isEmpty() && listObservers.isEmpty() && _sizeVal.publicObservers.isEmpty()) {
+        if (observers.isEmpty() && listObservers.isEmpty() && _size.publicObservers.isEmpty()) {
             hasObservers = false
             lastObserverRemoved()
         }
@@ -95,13 +95,13 @@ abstract class AbstractDependentListVal<E>(
 
     override fun finalizeUpdate(event: ListChangeEvent<E>) {
         if (event is ListChangeEvent.Change && event.removed.size != event.inserted.size) {
-            _sizeVal.publicEmit()
+            _size.publicEmit()
         }
 
         super.finalizeUpdate(event)
     }
 
-    private inner class SizeVal : AbstractVal<Int>() {
+    private inner class SizeCell : AbstractCell<Int>() {
         override val value: Int
             get() {
                 if (!hasObservers) {

observable/src/commonMain/kotlin/world/phantasmal/observable/cell/list/AbstractListCell.kt

@@ -1,4 +1,4 @@
-package world.phantasmal.observable.value.list
+package world.phantasmal.observable.cell.list
 
 import world.phantasmal.core.disposable.Disposable
 import world.phantasmal.core.disposable.disposable
@@ -6,14 +6,14 @@ import world.phantasmal.core.unsafe.unsafeAssertNotNull
 import world.phantasmal.observable.ChangeEvent
 import world.phantasmal.observable.Observable
 import world.phantasmal.observable.Observer
-import world.phantasmal.observable.value.AbstractVal
+import world.phantasmal.observable.cell.AbstractCell
-import world.phantasmal.observable.value.DependentVal
+import world.phantasmal.observable.cell.Cell
-import world.phantasmal.observable.value.Val
+import world.phantasmal.observable.cell.DependentCell
-import world.phantasmal.observable.value.not
+import world.phantasmal.observable.cell.not
 
-abstract class AbstractListVal<E>(
+abstract class AbstractListCell<E>(
     private val extractObservables: ObservablesExtractor<E>?,
-) : AbstractVal<List<E>>(), ListVal<E> {
+) : AbstractCell<List<E>>(), ListCell<E> {
     /**
      * Internal observers which observe observables related to this list's elements so that their
      * changes can be propagated via ElementChange events.
@@ -23,11 +23,11 @@ abstract class AbstractListVal<E>(
     /**
      * External list observers which are observing this list.
      */
-    protected val listObservers = mutableListOf<ListValObserver<E>>()
+    protected val listObservers = mutableListOf<ListObserver<E>>()
 
-    override val empty: Val<Boolean> by lazy { size.map { it == 0 } }
+    override val empty: Cell<Boolean> by lazy { size.map { it == 0 } }
 
-    override val notEmpty: Val<Boolean> by lazy { !empty }
+    override val notEmpty: Cell<Boolean> by lazy { !empty }
 
     override fun get(index: Int): E =
         value[index]
@@ -49,7 +49,7 @@ abstract class AbstractListVal<E>(
         }
     }
 
-    override fun observeList(callNow: Boolean, observer: ListValObserver<E>): Disposable {
+    override fun observeList(callNow: Boolean, observer: ListObserver<E>): Disposable {
         if (elementObservers.isEmpty() && extractObservables != null) {
             replaceElementObservers(0, elementObservers.size, value)
         }
@@ -66,14 +66,14 @@ abstract class AbstractListVal<E>(
         }
     }
 
-    override fun firstOrNull(): Val<E?> =
+    override fun firstOrNull(): Cell<E?> =
-        DependentVal(this) { value.firstOrNull() }
+        DependentCell(this) { value.firstOrNull() }
 
     /**
      * Does the following in the given order:
      * - Updates element observers
-     * - Emits ListValChangeEvent
+     * - Emits ListChangeEvent
-     * - Emits ValChangeEvent
+     * - Emits ChangeEvent
      */
     protected open fun finalizeUpdate(event: ListChangeEvent<E>) {
         if (
@@ -84,7 +84,7 @@ abstract class AbstractListVal<E>(
             replaceElementObservers(event.index, event.removed.size, event.inserted)
         }
 
-        listObservers.forEach { observer: ListValObserver<E> ->
+        listObservers.forEach { observer: ListObserver<E> ->
             observer(event)
         }
 

observable/src/commonMain/kotlin/world/phantasmal/observable/cell/list/DependentListCell.kt

@@ -1,15 +1,15 @@
-package world.phantasmal.observable.value.list
+package world.phantasmal.observable.cell.list
 
 import world.phantasmal.core.unsafe.unsafeAssertNotNull
-import world.phantasmal.observable.value.Val
+import world.phantasmal.observable.cell.Cell
 
 /**
- * ListVal of which the value depends on 0 or more other vals.
+ * ListCell of which the value depends on 0 or more other cells.
  */
-class DependentListVal<E>(
+class DependentListCell<E>(
-    vararg dependencies: Val<*>,
+    vararg dependencies: Cell<*>,
     private val computeElements: () -> List<E>,
-) : AbstractDependentListVal<E>(*dependencies) {
+) : AbstractDependentListCell<E>(*dependencies) {
     private var _elements: List<E>? = null
 
     override val elements: List<E> get() = _elements.unsafeAssertNotNull()

observable/src/commonMain/kotlin/world/phantasmal/observable/cell/list/FilteredListCell.kt

@@ -1,17 +1,17 @@
-package world.phantasmal.observable.value.list
+package world.phantasmal.observable.cell.list
 
 import world.phantasmal.core.disposable.Disposable
 import world.phantasmal.core.disposable.disposable
 import world.phantasmal.observable.Observer
-import world.phantasmal.observable.value.AbstractVal
+import world.phantasmal.observable.cell.AbstractCell
-import world.phantasmal.observable.value.Val
+import world.phantasmal.observable.cell.Cell
 
-// TODO: This class shares 95% of its code with AbstractDependentListVal.
+// TODO: This class shares 95% of its code with AbstractDependentListCell.
-class FilteredListVal<E>(
+class FilteredListCell<E>(
-    private val dependency: ListVal<E>,
+    private val dependency: ListCell<E>,
     private val predicate: (E) -> Boolean,
-) : AbstractListVal<E>(extractObservables = null) {
+) : AbstractListCell<E>(extractObservables = null) {
-    private val _sizeVal = SizeVal()
+    private val _size = SizeCell()
 
     /**
      * Set to true right before actual observers are added.
@@ -37,7 +37,7 @@ class FilteredListVal<E>(
             return elements
         }
 
-    override val size: Val<Int> = _sizeVal
+    override val size: Cell<Int> = _size
 
     override fun observe(callNow: Boolean, observer: Observer<List<E>>): Disposable {
         initDependencyObservers()
@@ -50,7 +50,7 @@ class FilteredListVal<E>(
         }
     }
 
-    override fun observeList(callNow: Boolean, observer: ListValObserver<E>): Disposable {
+    override fun observeList(callNow: Boolean, observer: ListObserver<E>): Disposable {
         initDependencyObservers()
 
         val superDisposable = super.observeList(callNow, observer)
@@ -201,7 +201,7 @@ class FilteredListVal<E>(
     }
 
     private fun disposeDependencyObservers() {
-        if (observers.isEmpty() && listObservers.isEmpty() && _sizeVal.publicObservers.isEmpty()) {
+        if (observers.isEmpty() && listObservers.isEmpty() && _size.publicObservers.isEmpty()) {
             hasObservers = false
             dependencyObserver?.dispose()
             dependencyObserver = null
@@ -210,13 +210,13 @@ class FilteredListVal<E>(
 
     override fun finalizeUpdate(event: ListChangeEvent<E>) {
         if (event is ListChangeEvent.Change && event.removed.size != event.inserted.size) {
-            _sizeVal.publicEmit()
+            _size.publicEmit()
         }
 
         super.finalizeUpdate(event)
     }
 
-    private inner class SizeVal : AbstractVal<Int>() {
+    private inner class SizeCell : AbstractCell<Int>() {
         override val value: Int
             get() {
                 if (!hasObservers) {

observable/src/commonMain/kotlin/world/phantasmal/observable/cell/list/FlatteningDependentListCell.kt

@@ -0,0 +1,38 @@
+package world.phantasmal.observable.cell.list
+
+import world.phantasmal.core.disposable.Disposable
+import world.phantasmal.core.unsafe.unsafeAssertNotNull
+import world.phantasmal.observable.cell.Cell
+
+/**
+ * Similar to [DependentListCell], except that this cell's [computeElements] returns a [ListCell].
+ */
+class FlatteningDependentListCell<E>(
+    vararg dependencies: Cell<*>,
+    private val computeElements: () -> ListCell<E>,
+) : AbstractDependentListCell<E>(*dependencies) {
+    private var computedCell: ListCell<E>? = null
+    private var computedCellObserver: Disposable? = null
+
+    override val elements: List<E> get() = computedCell.unsafeAssertNotNull().value
+
+    override fun computeElements() {
+        computedCell = computeElements.invoke()
+
+        computedCellObserver?.dispose()
+
+        computedCellObserver =
+            if (hasObservers) {
+                computedCell.unsafeAssertNotNull().observeList(observer = ::finalizeUpdate)
+            } else {
+                null
+            }
+    }
+
+    override fun lastObserverRemoved() {
+        super.lastObserverRemoved()
+
+        computedCellObserver?.dispose()
+        computedCellObserver = null
+    }
+}

observable/src/commonMain/kotlin/world/phantasmal/observable/cell/list/FoldedCell.kt

@@ -1,16 +1,16 @@
-package world.phantasmal.observable.value.list
+package world.phantasmal.observable.cell.list
 
 import world.phantasmal.core.disposable.Disposable
 import world.phantasmal.core.disposable.disposable
-import world.phantasmal.core.unsafe.unsafeAssertNotNull
+import world.phantasmal.core.unsafe.unsafeCast
 import world.phantasmal.observable.Observer
-import world.phantasmal.observable.value.AbstractVal
+import world.phantasmal.observable.cell.AbstractCell
 
-class FoldedVal<T, R>(
+class FoldedCell<T, R>(
-    private val dependency: ListVal<T>,
+    private val dependency: ListCell<T>,
     private val initial: R,
     private val operation: (R, T) -> R,
-) : AbstractVal<R>() {
+) : AbstractCell<R>() {
     private var dependencyDisposable: Disposable? = null
     private var _value: R? = null
 
@@ -19,7 +19,7 @@ class FoldedVal<T, R>(
             return if (dependencyDisposable == null) {
                 computeValue()
             } else {
-                _value.unsafeAssertNotNull()
+                _value.unsafeCast()
             }
         }
 

observable/src/commonMain/kotlin/world/phantasmal/observable/cell/list/ListCell.kt

@@ -0,0 +1,38 @@
+package world.phantasmal.observable.cell.list
+
+import world.phantasmal.core.disposable.Disposable
+import world.phantasmal.observable.cell.Cell
+
+interface ListCell<out E> : Cell<List<E>> {
+    /**
+     * Do not keep long-lived references to a [ListCell]'s [value], it may or may not be mutated
+     * when the [ListCell] is mutated.
+     */
+    override val value: List<E>
+
+    val size: Cell<Int>
+
+    val empty: Cell<Boolean>
+
+    val notEmpty: Cell<Boolean>
+
+    operator fun get(index: Int): E
+
+    fun observeList(callNow: Boolean = false, observer: ListObserver<E>): Disposable
+
+    fun <R> fold(initialValue: R, operation: (R, E) -> R): Cell<R> =
+        FoldedCell(this, initialValue, operation)
+
+    fun all(predicate: (E) -> Boolean): Cell<Boolean> =
+        fold(true) { acc, el -> acc && predicate(el) }
+
+    fun sumBy(selector: (E) -> Int): Cell<Int> =
+        fold(0) { acc, el -> acc + selector(el) }
+
+    fun filtered(predicate: (E) -> Boolean): ListCell<E> =
+        FilteredListCell(this, predicate)
+
+    fun firstOrNull(): Cell<E?>
+
+    operator fun contains(element: @UnsafeVariance E): Boolean = element in value
+}

observable/src/commonMain/kotlin/world/phantasmal/observable/cell/list/ListCellCreation.kt

@@ -0,0 +1,21 @@
+package world.phantasmal.observable.cell.list
+
+import world.phantasmal.observable.cell.Cell
+
+private val EMPTY_LIST_CELL = StaticListCell<Nothing>(emptyList())
+
+fun <E> listCell(vararg elements: E): ListCell<E> = StaticListCell(elements.toList())
+
+fun <E> emptyListCell(): ListCell<E> = EMPTY_LIST_CELL
+
+fun <E> mutableListCell(
+    vararg elements: E,
+    extractObservables: ObservablesExtractor<E>? = null,
+): MutableListCell<E> = SimpleListCell(mutableListOf(*elements), extractObservables)
+
+fun <T1, T2, R> flatMapToList(
+    c1: Cell<T1>,
+    c2: Cell<T2>,
+    transform: (T1, T2) -> ListCell<R>,
+): ListCell<R> =
+    FlatteningDependentListCell(c1, c2) { transform(c1.value, c2.value) }

observable/src/commonMain/kotlin/world/phantasmal/observable/cell/list/ListObserver.kt

@@ -1,4 +1,4 @@
-package world.phantasmal.observable.value.list
+package world.phantasmal.observable.cell.list
 
 sealed class ListChangeEvent<out E> {
     abstract val index: Int
@@ -12,14 +12,14 @@ sealed class ListChangeEvent<out E> {
          * The elements that were removed from the list at [index].
          *
          * Do not keep long-lived references to a [Change]'s [removed] list, it may or may not be
-         * mutated when the originating [ListVal] is mutated.
+         * mutated when the originating [ListCell] is mutated.
          */
         val removed: List<E>,
         /**
          * The elements that were inserted into the list at [index].
          *
          * Do not keep long-lived references to a [Change]'s [inserted] list, it may or may not be
-         * mutated when the originating [ListVal] is mutated.
+         * mutated when the originating [ListCell] is mutated.
          */
         val inserted: List<E>,
     ) : ListChangeEvent<E>()
@@ -34,4 +34,4 @@ sealed class ListChangeEvent<out E> {
     ) : ListChangeEvent<E>()
 }
 
-typealias ListValObserver<E> = (change: ListChangeEvent<E>) -> Unit
+typealias ListObserver<E> = (change: ListChangeEvent<E>) -> Unit

observable/src/commonMain/kotlin/world/phantasmal/observable/cell/list/ListWrapper.kt

@@ -1,14 +1,14 @@
-package world.phantasmal.observable.value.list
+package world.phantasmal.observable.cell.list
 
 import kotlin.contracts.InvocationKind
 import kotlin.contracts.contract
 
 /**
- * Wrapper is used to ensure that ListVal.value of some implementations references a new object
+ * ListWrapper is used to ensure that ListCell.value of some implementations references a new object
- * after every change to the ListVal. This is done to honor the contract that emission of a
+ * after every change to the ListCell. This is done to honor the contract that emission of a
- * ChangeEvent implies that Val.value is no longer equal to the previous value.
+ * ChangeEvent implies that Cell.value is no longer equal to the previous value.
- * When a change is made to the ListVal, the underlying list of Wrapper is usually mutated and then
+ * When a change is made to the ListCell, the underlying list of ListWrapper is usually mutated and
- * a new Wrapper is created that points to the same underlying list.
+ * then a new wrapper is created that points to the same underlying list.
  */
 internal class ListWrapper<E>(private val mut: MutableList<E>) : List<E> by mut {
     inline fun mutate(mutator: MutableList<E>.() -> Unit): ListWrapper<E> {
@@ -19,6 +19,7 @@ internal class ListWrapper<E>(private val mut: MutableList<E>) : List<E> by mut
 
     override fun equals(other: Any?): Boolean {
         if (this === other) return true
+        // If other is also a ListWrapper but it's not the exact same object then it's not equal.
         if (other == null || this::class == other::class || other !is List<*>) return false
         // If other is a list but not a ListWrapper, call its equals method for a structured
         // comparison.

observable/src/commonMain/kotlin/world/phantasmal/observable/cell/list/MutableListCell.kt

@@ -1,8 +1,8 @@
-package world.phantasmal.observable.value.list
+package world.phantasmal.observable.cell.list
 
-import world.phantasmal.observable.value.MutableVal
+import world.phantasmal.observable.cell.MutableCell
 
-interface MutableListVal<E> : ListVal<E>, MutableVal<List<E>> {
+interface MutableListCell<E> : ListCell<E>, MutableCell<List<E>> {
     operator fun set(index: Int, element: E): E
 
     fun add(element: E)

observable/src/commonMain/kotlin/world/phantasmal/observable/cell/list/SimpleListCell.kt

@@ -1,23 +1,23 @@
-package world.phantasmal.observable.value.list
+package world.phantasmal.observable.cell.list
 
 import world.phantasmal.observable.Observable
-import world.phantasmal.observable.value.MutableVal
+import world.phantasmal.observable.cell.Cell
-import world.phantasmal.observable.value.Val
+import world.phantasmal.observable.cell.MutableCell
-import world.phantasmal.observable.value.mutableVal
+import world.phantasmal.observable.cell.mutableCell
 
 typealias ObservablesExtractor<E> = (element: E) -> Array<Observable<*>>
 
 /**
- * @param elements The backing list for this ListVal
+ * @param elements The backing list for this [ListCell]
  * @param extractObservables Extractor function called on each element in this list, changes to the
  * returned observables will be propagated via ElementChange events
  */
-class SimpleListVal<E>(
+class SimpleListCell<E>(
     elements: MutableList<E>,
     extractObservables: ObservablesExtractor<E>? = null,
-) : AbstractListVal<E>(extractObservables), MutableListVal<E> {
+) : AbstractListCell<E>(extractObservables), MutableListCell<E> {
     private var elements = ListWrapper(elements)
-    private val _sizeVal: MutableVal<Int> = mutableVal(elements.size)
+    private val _size: MutableCell<Int> = mutableCell(elements.size)
 
     override var value: List<E>
         get() = elements
@@ -25,7 +25,7 @@ class SimpleListVal<E>(
             replaceAll(value)
         }
 
-    override val size: Val<Int> = _sizeVal
+    override val size: Cell<Int> = _size
 
     override operator fun get(index: Int): E =
         elements[index]
@@ -99,7 +99,7 @@ class SimpleListVal<E>(
     }
 
     override fun finalizeUpdate(event: ListChangeEvent<E>) {
-        _sizeVal.value = elements.size
+        _size.value = elements.size
         super.finalizeUpdate(event)
     }
 }

observable/src/commonMain/kotlin/world/phantasmal/observable/cell/list/StaticListCell.kt

@@ -0,0 +1,40 @@
+package world.phantasmal.observable.cell.list
+
+import world.phantasmal.core.disposable.Disposable
+import world.phantasmal.core.disposable.nopDisposable
+import world.phantasmal.observable.ChangeEvent
+import world.phantasmal.observable.Observer
+import world.phantasmal.observable.cell.*
+
+class StaticListCell<E>(private val elements: List<E>) : ListCell<E> {
+    private val firstOrNull = StaticCell(elements.firstOrNull())
+
+    override val size: Cell<Int> = cell(elements.size)
+    override val empty: Cell<Boolean> = if (elements.isEmpty()) trueCell() else falseCell()
+    override val notEmpty: Cell<Boolean> = if (elements.isNotEmpty()) trueCell() else falseCell()
+
+    override val value: List<E> = elements
+
+    override fun get(index: Int): E =
+        elements[index]
+
+    override fun observe(callNow: Boolean, observer: Observer<List<E>>): Disposable {
+        if (callNow) {
+            observer(ChangeEvent(value))
+        }
+
+        return nopDisposable()
+    }
+
+    override fun observe(observer: Observer<List<E>>): Disposable = nopDisposable()
+
+    override fun observeList(callNow: Boolean, observer: ListObserver<E>): Disposable {
+        if (callNow) {
+            observer(ListChangeEvent.Change(0, emptyList(), value))
+        }
+
+        return nopDisposable()
+    }
+
+    override fun firstOrNull(): Cell<E?> = firstOrNull
+}

observable/src/commonMain/kotlin/world/phantasmal/observable/value/DependentVal.kt

@@ -1,11 +0,0 @@
-package world.phantasmal.observable.value
-
-/**
- * Val of which the value depends on 0 or more other vals.
- */
-class DependentVal<T>(
-    vararg dependencies: Val<*>,
-    private val compute: () -> T,
-) : AbstractDependentVal<T>(*dependencies) {
-    override fun computeValue(): T = compute()
-}

observable/src/commonMain/kotlin/world/phantasmal/observable/value/Val.kt

@@ -1,51 +0,0 @@
-package world.phantasmal.observable.value
-
-import world.phantasmal.core.disposable.Disposable
-import world.phantasmal.observable.Observable
-import world.phantasmal.observable.Observer
-import world.phantasmal.observable.value.list.DependentListVal
-import world.phantasmal.observable.value.list.ListVal
-import kotlin.reflect.KProperty
-
-/**
- * An observable with the notion of a current [value].
- */
-interface Val<out T> : Observable<T> {
-    val value: T
-
-    operator fun getValue(thisRef: Any?, property: KProperty<*>): T = value
-
-    /**
-     * @param callNow Call [observer] immediately with the current [mutableVal].
-     */
-    fun observe(callNow: Boolean = false, observer: Observer<T>): Disposable
-
-    /**
-     * Map a transformation function over this val.
-     *
-     * @param transform called whenever this val changes
-     */
-    fun <R> map(transform: (T) -> R): Val<R> =
-        DependentVal(this) { transform(value) }
-
-    fun <R> mapToListVal(transform: (T) -> List<R>): ListVal<R> =
-        DependentListVal(this) { transform(value) }
-
-    /**
-     * Map a transformation function that returns a val over this val. The resulting val will change
-     * when this val changes and when the val returned by [transform] changes.
-     *
-     * @param transform called whenever this val changes
-     */
-    fun <R> flatMap(transform: (T) -> Val<R>): Val<R> =
-        FlatteningDependentVal(this) { transform(value) }
-
-    fun <R> flatMapNull(transform: (T) -> Val<R>?): Val<R?> =
-        FlatteningDependentVal(this) { transform(value) ?: nullVal() }
-
-    fun isNull(): Val<Boolean> =
-        map { it == null }
-
-    fun isNotNull(): Val<Boolean> =
-        map { it != null }
-}

observable/src/commonMain/kotlin/world/phantasmal/observable/value/ValCreation.kt

@@ -1,72 +0,0 @@
-package world.phantasmal.observable.value
-
-private val TRUE_VAL: Val<Boolean> = StaticVal(true)
-private val FALSE_VAL: Val<Boolean> = StaticVal(false)
-private val NULL_VAL: Val<Nothing?> = StaticVal(null)
-private val ZERO_INT_VAL: Val<Int> = StaticVal(0)
-private val EMPTY_STRING_VAL: Val<String> = StaticVal("")
-
-fun <T> value(value: T): Val<T> = StaticVal(value)
-
-fun trueVal(): Val<Boolean> = TRUE_VAL
-
-fun falseVal(): Val<Boolean> = FALSE_VAL
-
-fun nullVal(): Val<Nothing?> = NULL_VAL
-
-fun zeroIntVal(): Val<Int> = ZERO_INT_VAL
-
-fun emptyStringVal(): Val<String> = EMPTY_STRING_VAL
-
-/**
- * Creates a [MutableVal] with initial value [value].
- */
-fun <T> mutableVal(value: T): MutableVal<T> = SimpleVal(value)
-
-/**
- * Creates a [MutableVal] which calls [getter] or [setter] when its value is being read or written
- * to, respectively.
- */
-fun <T> mutableVal(getter: () -> T, setter: (T) -> Unit): MutableVal<T> =
-    DelegatingVal(getter, setter)
-
-/**
- * Map a transformation function over 2 vals.
- *
- * @param transform called whenever [v1] or [v2] changes
- */
-fun <T1, T2, R> map(
-    v1: Val<T1>,
-    v2: Val<T2>,
-    transform: (T1, T2) -> R,
-): Val<R> =
-    DependentVal(v1, v2) { transform(v1.value, v2.value) }
-
-/**
- * Map a transformation function over 3 vals.
- *
- * @param transform called whenever [v1], [v2] or [v3] changes
- */
-fun <T1, T2, T3, R> map(
-    v1: Val<T1>,
-    v2: Val<T2>,
-    v3: Val<T3>,
-    transform: (T1, T2, T3) -> R,
-): Val<R> =
-    DependentVal(v1, v2, v3) { transform(v1.value, v2.value, v3.value) }
-
-/**
- * Map a transformation function that returns a val over 2 vals. The resulting val will change when
- * either val changes and also when the val returned by [transform] changes.
- *
- * @param transform called whenever this val changes
- */
-fun <T1, T2, R> flatMap(
-    v1: Val<T1>,
-    v2: Val<T2>,
-    transform: (T1, T2) -> Val<R>,
-): Val<R> =
-    FlatteningDependentVal(v1, v2) { transform(v1.value, v2.value) }
-
-fun and(vararg vals: Val<Boolean>): Val<Boolean> =
-    DependentVal(*vals) { vals.all { it.value } }

observable/src/commonMain/kotlin/world/phantasmal/observable/value/ValExtensions.kt

@@ -1,61 +0,0 @@
-package world.phantasmal.observable.value
-
-infix fun <T> Val<T>.eq(value: T): Val<Boolean> =
-    map { it == value }
-
-infix fun <T> Val<T>.eq(value: Val<T>): Val<Boolean> =
-    map(this, value) { a, b -> a == b }
-
-infix fun <T> Val<T>.ne(value: T): Val<Boolean> =
-    map { it != value }
-
-infix fun <T> Val<T>.ne(value: Val<T>): Val<Boolean> =
-    map(this, value) { a, b -> a != b }
-
-fun <T> Val<T?>.orElse(defaultValue: () -> T): Val<T> =
-    map { it ?: defaultValue() }
-
-infix fun <T : Comparable<T>> Val<T>.gt(value: T): Val<Boolean> =
-    map { it > value }
-
-infix fun <T : Comparable<T>> Val<T>.gt(value: Val<T>): Val<Boolean> =
-    map(this, value) { a, b -> a > b }
-
-infix fun <T : Comparable<T>> Val<T>.lt(value: T): Val<Boolean> =
-    map { it < value }
-
-infix fun <T : Comparable<T>> Val<T>.lt(value: Val<T>): Val<Boolean> =
-    map(this, value) { a, b -> a < b }
-
-infix fun Val<Boolean>.and(other: Val<Boolean>): Val<Boolean> =
-    map(this, other) { a, b -> a && b }
-
-infix fun Val<Boolean>.and(other: Boolean): Val<Boolean> =
-    if (other) this else falseVal()
-
-infix fun Val<Boolean>.or(other: Val<Boolean>): Val<Boolean> =
-    map(this, other) { a, b -> a || b }
-
-infix fun Val<Boolean>.xor(other: Val<Boolean>): Val<Boolean> =
-    // Use != because of https://youtrack.jetbrains.com/issue/KT-31277.
-    map(this, other) { a, b -> a != b }
-
-operator fun Val<Boolean>.not(): Val<Boolean> = map { !it }
-
-operator fun Val<Int>.plus(other: Int): Val<Int> =
-    map { it + other }
-
-operator fun Val<Int>.minus(other: Int): Val<Int> =
-    map { it - other }
-
-fun Val<String>.isEmpty(): Val<Boolean> =
-    map { it.isEmpty() }
-
-fun Val<String>.isNotEmpty(): Val<Boolean> =
-    map { it.isNotEmpty() }
-
-fun Val<String>.isBlank(): Val<Boolean> =
-    map { it.isBlank() }
-
-fun Val<String>.isNotBlank(): Val<Boolean> =
-    map { it.isNotBlank() }

observable/src/commonMain/kotlin/world/phantasmal/observable/value/list/FlatteningDependentListVal.kt

@@ -1,38 +0,0 @@
-package world.phantasmal.observable.value.list
-
-import world.phantasmal.core.disposable.Disposable
-import world.phantasmal.core.unsafe.unsafeAssertNotNull
-import world.phantasmal.observable.value.Val
-
-/**
- * Similar to [DependentListVal], except that this val's [computeElements] returns a ListVal.
- */
-class FlatteningDependentListVal<E>(
-    vararg dependencies: Val<*>,
-    private val computeElements: () -> ListVal<E>,
-) : AbstractDependentListVal<E>(*dependencies) {
-    private var computedVal: ListVal<E>? = null
-    private var computedValObserver: Disposable? = null
-
-    override val elements: List<E> get() = computedVal.unsafeAssertNotNull().value
-
-    override fun computeElements() {
-        computedVal = computeElements.invoke()
-
-        computedValObserver?.dispose()
-
-        computedValObserver =
-            if (hasObservers) {
-                computedVal.unsafeAssertNotNull().observeList(observer = ::finalizeUpdate)
-            } else {
-                null
-            }
-    }
-
-    override fun lastObserverRemoved() {
-        super.lastObserverRemoved()
-
-        computedValObserver?.dispose()
-        computedValObserver = null
-    }
-}

observable/src/commonMain/kotlin/world/phantasmal/observable/value/list/ListVal.kt

@@ -1,38 +0,0 @@
-package world.phantasmal.observable.value.list
-
-import world.phantasmal.core.disposable.Disposable
-import world.phantasmal.observable.value.Val
-
-interface ListVal<out E> : Val<List<E>> {
-    /**
-     * Do not keep long-lived references to a [ListVal]'s [value], it may or may not be mutated
-     * when the [ListVal] is mutated.
-     */
-    override val value: List<E>
-
-    val size: Val<Int>
-
-    val empty: Val<Boolean>
-
-    val notEmpty: Val<Boolean>
-
-    operator fun get(index: Int): E
-
-    fun observeList(callNow: Boolean = false, observer: ListValObserver<E>): Disposable
-
-    fun <R> fold(initialValue: R, operation: (R, E) -> R): Val<R> =
-        FoldedVal(this, initialValue, operation)
-
-    fun all(predicate: (E) -> Boolean): Val<Boolean> =
-        fold(true) { acc, el -> acc && predicate(el) }
-
-    fun sumBy(selector: (E) -> Int): Val<Int> =
-        fold(0) { acc, el -> acc + selector(el) }
-
-    fun filtered(predicate: (E) -> Boolean): ListVal<E> =
-        FilteredListVal(this, predicate)
-
-    fun firstOrNull(): Val<E?>
-
-    operator fun contains(element: @UnsafeVariance E): Boolean = element in value
-}

observable/src/commonMain/kotlin/world/phantasmal/observable/value/list/ListValCreation.kt

@@ -1,21 +0,0 @@
-package world.phantasmal.observable.value.list
-
-import world.phantasmal.observable.value.Val
-
-private val EMPTY_LIST_VAL = StaticListVal<Nothing>(emptyList())
-
-fun <E> listVal(vararg elements: E): ListVal<E> = StaticListVal(elements.toList())
-
-fun <E> emptyListVal(): ListVal<E> = EMPTY_LIST_VAL
-
-fun <E> mutableListVal(
-    vararg elements: E,
-    extractObservables: ObservablesExtractor<E>? = null,
-): MutableListVal<E> = SimpleListVal(mutableListOf(*elements), extractObservables)
-
-fun <T1, T2, R> flatMapToList(
-    v1: Val<T1>,
-    v2: Val<T2>,
-    transform: (T1, T2) -> ListVal<R>,
-): ListVal<R> =
-    FlatteningDependentListVal(v1, v2) { transform(v1.value, v2.value) }

observable/src/commonMain/kotlin/world/phantasmal/observable/value/list/StaticListVal.kt

@@ -1,40 +0,0 @@
-package world.phantasmal.observable.value.list
-
-import world.phantasmal.core.disposable.Disposable
-import world.phantasmal.core.disposable.stubDisposable
-import world.phantasmal.observable.ChangeEvent
-import world.phantasmal.observable.Observer
-import world.phantasmal.observable.value.*
-
-class StaticListVal<E>(private val elements: List<E>) : ListVal<E> {
-    private val firstOrNull = StaticVal(elements.firstOrNull())
-
-    override val size: Val<Int> = value(elements.size)
-    override val empty: Val<Boolean> = if (elements.isEmpty()) trueVal() else falseVal()
-    override val notEmpty: Val<Boolean> = if (elements.isNotEmpty()) trueVal() else falseVal()
-
-    override val value: List<E> = elements
-
-    override fun get(index: Int): E =
-        elements[index]
-
-    override fun observe(callNow: Boolean, observer: Observer<List<E>>): Disposable {
-        if (callNow) {
-            observer(ChangeEvent(value))
-        }
-
-        return stubDisposable()
-    }
-
-    override fun observe(observer: Observer<List<E>>): Disposable = stubDisposable()
-
-    override fun observeList(callNow: Boolean, observer: ListValObserver<E>): Disposable {
-        if (callNow) {
-            observer(ListChangeEvent.Change(0, emptyList(), value))
-        }
-
-        return stubDisposable()
-    }
-
-    override fun firstOrNull(): Val<E?> = firstOrNull
-}

observable/src/commonTest/kotlin/world/phantasmal/observable/cell/CellCreationTests.kt

@@ -0,0 +1,49 @@
+package world.phantasmal.observable.cell
+
+import world.phantasmal.observable.test.ObservableTestSuite
+import kotlin.test.*
+
+class CellCreationTests : ObservableTestSuite {
+    @Test
+    fun test_cell() = test {
+        assertEquals(7, cell(7).value)
+    }
+
+    @Test
+    fun test_trueCell() = test {
+        assertTrue(trueCell().value)
+    }
+
+    @Test
+    fun test_falseCell() = test {
+        assertFalse(falseCell().value)
+    }
+
+    @Test
+    fun test_nullCell() = test {
+        assertNull(nullCell().value)
+    }
+
+    @Test
+    fun test_mutableCell_with_initial_value() = test {
+        val cell = mutableCell(17)
+
+        assertEquals(17, cell.value)
+
+        cell.value = 201
+
+        assertEquals(201, cell.value)
+    }
+
+    @Test
+    fun test_mutableCell_with_getter_and_setter() = test {
+        var x = 17
+        val cell = mutableCell({ x }, { x = it })
+
+        assertEquals(17, cell.value)
+
+        cell.value = 201
+
+        assertEquals(201, cell.value)
+    }
+}

observable/src/commonTest/kotlin/world/phantasmal/observable/cell/CellTests.kt

@@ -1,18 +1,18 @@
-package world.phantasmal.observable.value
+package world.phantasmal.observable.cell
 
 import world.phantasmal.core.disposable.use
 import world.phantasmal.observable.ObservableTests
 import kotlin.test.*
 
 /**
- * Test suite for all [Val] implementations. There is a subclass of this suite for every [Val]
+ * Test suite for all [Cell] implementations. There is a subclass of this suite for every [Cell]
  * implementation.
  */
-interface ValTests : ObservableTests {
+interface CellTests : ObservableTests {
     override fun createProvider(): Provider
 
     @Test
-    fun propagates_changes_to_mapped_val() = test {
+    fun propagates_changes_to_mapped_cell() = test {
         val p = createProvider()
         val mapped = p.observable.map { it.hashCode() }
         val initialValue = mapped.value
@@ -31,10 +31,10 @@ interface ValTests : ObservableTests {
     }
 
     @Test
-    fun propagates_changes_to_flat_mapped_val() = test {
+    fun propagates_changes_to_flat_mapped_cell() = test {
         val p = createProvider()
 
-        val mapped = p.observable.flatMap { StaticVal(it.hashCode()) }
+        val mapped = p.observable.flatMap { StaticCell(it.hashCode()) }
         val initialValue = mapped.value
 
         var observedValue: Int? = null
@@ -72,7 +72,7 @@ interface ValTests : ObservableTests {
     }
 
     /**
-     * When [Val.observe] is called with callNow = true, it should call the observer immediately.
+     * When [Cell.observe] is called with callNow = true, it should call the observer immediately.
      * Otherwise it should only call the observer when it changes.
      */
     @Test
@@ -102,6 +102,6 @@ interface ValTests : ObservableTests {
     }
 
     interface Provider : ObservableTests.Provider {
-        override val observable: Val<Any>
+        override val observable: Cell<Any>
     }
 }

observable/src/commonTest/kotlin/world/phantasmal/observable/cell/DelegatingCellTests.kt

@@ -0,0 +1,20 @@
+package world.phantasmal.observable.cell
+
+class DelegatingCellTests : RegularCellTests, MutableCellTests<Int> {
+    override fun createProvider() = object : MutableCellTests.Provider<Int> {
+        private var v = 0
+
+        override val observable = DelegatingCell({ v }, { v = it })
+
+        override fun emit() {
+            observable.value += 2
+        }
+
+        override fun createValue(): Int = v + 1
+    }
+
+    override fun <T> createWithValue(value: T): DelegatingCell<T> {
+        var v = value
+        return DelegatingCell({ v }, { v = it })
+    }
+}

observable/src/commonTest/kotlin/world/phantasmal/observable/cell/DependentCellTests.kt

@@ -0,0 +1,18 @@
+package world.phantasmal.observable.cell
+
+class DependentCellTests : RegularCellTests {
+    override fun createProvider() = object : CellTests.Provider {
+        val dependency = SimpleCell(0)
+
+        override val observable = DependentCell(dependency) { 2 * dependency.value }
+
+        override fun emit() {
+            dependency.value += 2
+        }
+    }
+
+    override fun <T> createWithValue(value: T): DependentCell<T> {
+        val dependency = SimpleCell(value)
+        return DependentCell(dependency) { dependency.value }
+    }
+}

observable/src/commonTest/kotlin/world/phantasmal/observable/cell/FlatteningDependentCellDirectDependencyEmitsTests.kt

@@ -0,0 +1,28 @@
+package world.phantasmal.observable.cell
+
+/**
+ * In these tests the direct dependency of the [FlatteningDependentCell] changes.
+ */
+class FlatteningDependentCellDirectDependencyEmitsTests : RegularCellTests {
+    override fun createProvider() = object : CellTests.Provider {
+        // The transitive dependency can't change.
+        val transitiveDependency = StaticCell(5)
+
+        // The direct dependency of the cell under test can change.
+        val directDependency = SimpleCell(transitiveDependency)
+
+        override val observable =
+            FlatteningDependentCell(directDependency) { directDependency.value }
+
+        override fun emit() {
+            // Update the direct dependency.
+            val oldTransitiveDependency = directDependency.value
+            directDependency.value = StaticCell(oldTransitiveDependency.value + 5)
+        }
+    }
+
+    override fun <T> createWithValue(value: T): FlatteningDependentCell<T> {
+        val v = StaticCell(StaticCell(value))
+        return FlatteningDependentCell(v) { v.value }
+    }
+}

observable/src/commonTest/kotlin/world/phantasmal/observable/cell/FlatteningDependentCellTransitiveDependencyEmitsTests.kt

@@ -0,0 +1,27 @@
+package world.phantasmal.observable.cell
+
+/**
+ * In these tests the dependency of the [FlatteningDependentCell]'s direct dependency changes.
+ */
+class FlatteningDependentCellTransitiveDependencyEmitsTests : RegularCellTests {
+    override fun createProvider() = object : CellTests.Provider {
+        // The transitive dependency can change.
+        val transitiveDependency = SimpleCell(5)
+
+        // The direct dependency of the cell under test can't change.
+        val directDependency = StaticCell(transitiveDependency)
+
+        override val observable =
+            FlatteningDependentCell(directDependency) { directDependency.value }
+
+        override fun emit() {
+            // Update the transitive dependency.
+            transitiveDependency.value += 5
+        }
+    }
+
+    override fun <T> createWithValue(value: T): FlatteningDependentCell<T> {
+        val dependency = StaticCell(StaticCell(value))
+        return FlatteningDependentCell(dependency) { dependency.value }
+    }
+}

observable/src/commonTest/kotlin/world/phantasmal/observable/cell/MutableCellTests.kt

@@ -1,10 +1,10 @@
-package world.phantasmal.observable.value
+package world.phantasmal.observable.cell
 
 import kotlin.test.Test
 import kotlin.test.assertEquals
 import kotlin.test.assertNull
 
-interface MutableValTests<T : Any> : ValTests {
+interface MutableCellTests<T : Any> : CellTests {
     override fun createProvider(): Provider<T>
 
     @Test
@@ -25,8 +25,8 @@ interface MutableValTests<T : Any> : ValTests {
         assertEquals(newValue, observedValue)
     }
 
-    interface Provider<T : Any> : ValTests.Provider {
+    interface Provider<T : Any> : CellTests.Provider {
-        override val observable: MutableVal<T>
+        override val observable: MutableCell<T>
 
         /**
          * Returns a value that can be assigned to [observable] and that's different from

observable/src/commonTest/kotlin/world/phantasmal/observable/cell/RegularCellTests.kt

@@ -0,0 +1,161 @@
+package world.phantasmal.observable.cell
+
+import kotlin.test.*
+
+/**
+ * Test suite for all [Cell] implementations that aren't ListCells. There is a subclass of this
+ * suite for every non-ListCell [Cell] implementation.
+ */
+interface RegularCellTests : CellTests {
+    fun <T> createWithValue(value: T): Cell<T>
+
+    /**
+     * [Cell.value] should correctly reflect changes even when the [Cell] has no observers.
+     * Typically this means that the cell's value is not updated in real time, only when it is
+     * queried.
+     */
+    @Test
+    fun reflects_changes_without_observers() = test {
+        val p = createProvider()
+
+        var old: Any?
+
+        repeat(5) {
+            // Value should change after emit.
+            old = p.observable.value
+
+            p.emit()
+
+            val new = p.observable.value
+
+            assertNotEquals(old, new)
+
+            // Value should not change when emit hasn't been called since the last access.
+            assertEquals(new, p.observable.value)
+
+            old = new
+        }
+    }
+
+    @Test
+    fun convenience_methods() = test {
+        listOf(Any(), null).forEach { any ->
+            val anyCell = createWithValue(any)
+
+            // Test the test setup first.
+            assertEquals(any, anyCell.value)
+
+            // Test `isNull`.
+            assertEquals(any == null, anyCell.isNull().value)
+
+            // Test `isNotNull`.
+            assertEquals(any != null, anyCell.isNotNull().value)
+        }
+    }
+
+    @Test
+    fun generic_extensions() = test {
+        listOf(Any(), null).forEach { any ->
+            val anyCell = createWithValue(any)
+
+            // Test the test setup first.
+            assertEquals(any, anyCell.value)
+
+            // Test `orElse`.
+            assertEquals(any ?: "default", anyCell.orElse { "default" }.value)
+        }
+
+        fun <T> testEqNe(a: T, b: T) {
+            val aCell = createWithValue(a)
+            val bCell = createWithValue(b)
+
+            // Test the test setup first.
+            assertEquals(a, aCell.value)
+            assertEquals(b, bCell.value)
+
+            // Test `eq`.
+            assertEquals(a == b, (aCell eq b).value)
+            assertEquals(a == b, (aCell eq bCell).value)
+
+            // Test `ne`.
+            assertEquals(a != b, (aCell ne b).value)
+            assertEquals(a != b, (aCell ne bCell).value)
+        }
+
+        testEqNe(10, 10)
+        testEqNe(5, 99)
+        testEqNe("a", "a")
+        testEqNe("x", "y")
+    }
+
+    @Test
+    fun comparable_extensions() = test {
+        fun <T : Comparable<T>> comparable_tests(a: T, b: T) {
+            val aCell = createWithValue(a)
+            val bCell = createWithValue(b)
+
+            // Test the test setup first.
+            assertEquals(a, aCell.value)
+            assertEquals(b, bCell.value)
+
+            // Test `gt`.
+            assertEquals(a > b, (aCell gt b).value)
+            assertEquals(a > b, (aCell gt bCell).value)
+
+            // Test `lt`.
+            assertEquals(a < b, (aCell lt b).value)
+            assertEquals(a < b, (aCell lt bCell).value)
+        }
+
+        comparable_tests(10, 10)
+        comparable_tests(7.0, 5.0)
+        comparable_tests((5000).toShort(), (7000).toShort())
+    }
+
+    @Test
+    fun boolean_extensions() = test {
+        listOf(true, false).forEach { bool ->
+            val boolCell = createWithValue(bool)
+
+            // Test the test setup first.
+            assertEquals(bool, boolCell.value)
+
+            // Test `and`.
+            assertEquals(bool, (boolCell and trueCell()).value)
+            assertFalse((boolCell and falseCell()).value)
+
+            // Test `or`.
+            assertTrue((boolCell or trueCell()).value)
+            assertEquals(bool, (boolCell or falseCell()).value)
+
+            // Test `xor`.
+            assertEquals(!bool, (boolCell xor trueCell()).value)
+            assertEquals(bool, (boolCell xor falseCell()).value)
+
+            // Test `!` (unary not).
+            assertEquals(!bool, (!boolCell).value)
+        }
+    }
+
+    @Test
+    fun string_extensions() = test {
+        listOf("", "  ", "\t\t", "non-empty-non-blank").forEach { string ->
+            val stringCell = createWithValue(string)
+
+            // Test the test setup first.
+            assertEquals(string, stringCell.value)
+
+            // Test `isEmpty`.
+            assertEquals(string.isEmpty(), stringCell.isEmpty().value)
+
+            // Test `isNotEmpty`.
+            assertEquals(string.isNotEmpty(), stringCell.isNotEmpty().value)
+
+            // Test `isBlank`.
+            assertEquals(string.isBlank(), stringCell.isBlank().value)
+
+            // Test `isNotBlank`.
+            assertEquals(string.isNotBlank(), stringCell.isNotBlank().value)
+        }
+    }
+}

observable/src/commonTest/kotlin/world/phantasmal/observable/cell/SimpleCellTests.kt

@@ -0,0 +1,15 @@
+package world.phantasmal.observable.cell
+
+class SimpleCellTests : RegularCellTests, MutableCellTests<Int> {
+    override fun createProvider() = object : MutableCellTests.Provider<Int> {
+        override val observable = SimpleCell(1)
+
+        override fun emit() {
+            observable.value += 2
+        }
+
+        override fun createValue(): Int = observable.value + 1
+    }
+
+    override fun <T> createWithValue(value: T) = SimpleCell(value)
+}

observable/src/commonTest/kotlin/world/phantasmal/observable/cell/StaticCellTests.kt

@@ -1,14 +1,15 @@
-package world.phantasmal.observable.value
+package world.phantasmal.observable.cell
 
 import world.phantasmal.observable.test.ObservableTestSuite
 import kotlin.test.Test
 import kotlin.test.assertEquals
 
-class StaticValTests : ObservableTestSuite {
+class StaticCellTests : ObservableTestSuite {
     @Test
-    fun observing_StaticVal_should_never_create_leaks() = test {
+    fun observing_StaticCell_should_never_create_leaks() = test {
-        val static = StaticVal("test value")
+        val static = StaticCell("test value")
 
+        // We never call dispose on the returned disposables.
         static.observe {}
         static.observe(callNow = false) {}
         static.observe(callNow = true) {}
@@ -16,7 +17,7 @@ class StaticValTests : ObservableTestSuite {
 
     @Test
     fun observe_respects_callNow() = test {
-        val static = StaticVal("test value")
+        val static = StaticCell("test value")
         var calls = 0
 
         static.observe(callNow = false) { calls++ }

observable/src/commonTest/kotlin/world/phantasmal/observable/cell/list/DependentListCellTests.kt

@@ -0,0 +1,13 @@
+package world.phantasmal.observable.cell.list
+
+class DependentListCellTests : ListCellTests {
+    override fun createProvider() = object : ListCellTests.Provider {
+        private val dependency = SimpleListCell<Int>(mutableListOf())
+
+        override val observable = DependentListCell(dependency) { dependency.value.map { 2 * it } }
+
+        override fun addElement() {
+            dependency.add(4)
+        }
+    }
+}

observable/src/commonTest/kotlin/world/phantasmal/observable/cell/list/FilteredListCellTests.kt

@@ -1,15 +1,15 @@
-package world.phantasmal.observable.value.list
+package world.phantasmal.observable.cell.list
 
-import world.phantasmal.observable.value.SimpleVal
+import world.phantasmal.observable.cell.SimpleCell
 import kotlin.test.Test
 import kotlin.test.assertEquals
 import kotlin.test.assertNull
 
-class FilteredListValTests : ListValTests {
+class FilteredListCellTests : ListCellTests {
-    override fun createProvider() = object : ListValTests.Provider {
+    override fun createProvider() = object : ListCellTests.Provider {
-        private val dependency = SimpleListVal<Int>(mutableListOf())
+        private val dependency = SimpleListCell<Int>(mutableListOf())
 
-        override val observable = FilteredListVal(dependency, predicate = { it % 2 == 0 })
+        override val observable = FilteredListCell(dependency, predicate = { it % 2 == 0 })
 
         override fun addElement() {
             dependency.add(4)
@@ -18,8 +18,8 @@ class FilteredListValTests : ListValTests {
 
     @Test
     fun contains_only_values_that_match_the_predicate() = test {
-        val dep = SimpleListVal(mutableListOf("a", "b"))
+        val dep = SimpleListCell(mutableListOf("a", "b"))
-        val list = FilteredListVal(dep, predicate = { 'a' in it })
+        val list = FilteredListCell(dep, predicate = { 'a' in it })
 
         assertEquals(1, list.value.size)
         assertEquals("a", list.value[0])
@@ -42,8 +42,8 @@ class FilteredListValTests : ListValTests {
 
     @Test
     fun only_emits_when_necessary() = test {
-        val dep = SimpleListVal<Int>(mutableListOf())
+        val dep = SimpleListCell<Int>(mutableListOf())
-        val list = FilteredListVal(dep, predicate = { it % 2 == 0 })
+        val list = FilteredListCell(dep, predicate = { it % 2 == 0 })
         var changes = 0
         var listChanges = 0
 
@@ -71,8 +71,8 @@ class FilteredListValTests : ListValTests {
 
     @Test
     fun emits_correct_change_events() = test {
-        val dep = SimpleListVal<Int>(mutableListOf())
+        val dep = SimpleListCell<Int>(mutableListOf())
-        val list = FilteredListVal(dep, predicate = { it % 2 == 0 })
+        val list = FilteredListCell(dep, predicate = { it % 2 == 0 })
         var event: ListChangeEvent<Int>? = null
 
         disposer.add(list.observeList {
@@ -104,18 +104,18 @@ class FilteredListValTests : ListValTests {
     }
 
     /**
-     * When the dependency list of a FilteredListVal emits ElementChange events, the FilteredListVal
+     * When the dependency of a [FilteredListCell] emits ElementChange events, the
-     * should emit either Change events or ElementChange events, depending on whether the predicate
+     * [FilteredListCell] should emit either Change events or ElementChange events, depending on
-     * result has changed.
+     * whether the predicate result has changed.
      */
     @Test
     fun emits_correct_events_when_dependency_emits_ElementChange_events() = test {
-        val dep = SimpleListVal(
+        val dep = SimpleListCell(
-            mutableListOf(SimpleVal(1), SimpleVal(2), SimpleVal(3), SimpleVal(4)),
+            mutableListOf(SimpleCell(1), SimpleCell(2), SimpleCell(3), SimpleCell(4)),
             extractObservables = { arrayOf(it) },
         )
-        val list = FilteredListVal(dep, predicate = { it.value % 2 == 0 })
+        val list = FilteredListCell(dep, predicate = { it.value % 2 == 0 })
-        var event: ListChangeEvent<SimpleVal<Int>>? = null
+        var event: ListChangeEvent<SimpleCell<Int>>? = null
 
         disposer.add(list.observeList {
             assertNull(event)

observable/src/commonTest/kotlin/world/phantasmal/observable/cell/list/FlatteningDependentListCellDirectDependencyEmitsTests.kt

@@ -0,0 +1,25 @@
+package world.phantasmal.observable.cell.list
+
+import world.phantasmal.observable.cell.SimpleCell
+
+/**
+ * In these tests the direct dependency of the [FlatteningDependentListCell] changes.
+ */
+class FlatteningDependentListCellDirectDependencyEmitsTests : ListCellTests {
+    override fun createProvider() = object : ListCellTests.Provider {
+        // The transitive dependency can't change.
+        private val transitiveDependency = StaticListCell<Int>(emptyList())
+
+        // The direct dependency of the list under test can change.
+        private val dependency = SimpleCell<ListCell<Int>>(transitiveDependency)
+
+        override val observable =
+            FlatteningDependentListCell(dependency) { dependency.value }
+
+        override fun addElement() {
+            // Update the direct dependency.
+            val oldTransitiveDependency: ListCell<Int> = dependency.value
+            dependency.value = StaticListCell(oldTransitiveDependency.value + 4)
+        }
+    }
+}

observable/src/commonTest/kotlin/world/phantasmal/observable/cell/list/FlatteningDependentListCellTransitiveDependencyEmitsTests.kt

@@ -0,0 +1,24 @@
+package world.phantasmal.observable.cell.list
+
+import world.phantasmal.observable.cell.StaticCell
+
+/**
+ * In these tests the dependency of the [FlatteningDependentListCell]'s direct dependency changes.
+ */
+class FlatteningDependentListCellTransitiveDependencyEmitsTests : ListCellTests {
+    override fun createProvider() = object : ListCellTests.Provider {
+        // The transitive dependency can change.
+        private val transitiveDependency = SimpleListCell(mutableListOf<Int>())
+
+        // The direct dependency of the list under test can't change.
+        private val dependency = StaticCell<ListCell<Int>>(transitiveDependency)
+
+        override val observable =
+            FlatteningDependentListCell(dependency) { dependency.value }
+
+        override fun addElement() {
+            // Update the transitive dependency.
+            transitiveDependency.add(4)
+        }
+    }
+}

observable/src/commonTest/kotlin/world/phantasmal/observable/cell/list/ListCellTests.kt

@@ -1,13 +1,13 @@
-package world.phantasmal.observable.value.list
+package world.phantasmal.observable.cell.list
 
-import world.phantasmal.observable.value.ValTests
+import world.phantasmal.observable.cell.CellTests
 import kotlin.test.*
 
 /**
- * Test suite for all [ListVal] implementations. There is a subclass of this suite for every
+ * Test suite for all [ListCell] implementations. There is a subclass of this suite for every
- * [ListVal] implementation.
+ * [ListCell] implementation.
  */
-interface ListValTests : ValTests {
+interface ListCellTests : CellTests {
     override fun createProvider(): Provider
 
     @Test
@@ -177,11 +177,11 @@ interface ListValTests : ValTests {
         }
     }
 
-    interface Provider : ValTests.Provider {
+    interface Provider : CellTests.Provider {
-        override val observable: ListVal<Any>
+        override val observable: ListCell<Any>
 
         /**
-         * Adds an element to the ListVal under test.
+         * Adds an element to the [ListCell] under test.
          */
         fun addElement()
 

observable/src/commonTest/kotlin/world/phantasmal/observable/cell/list/MutableListCellTests.kt

@@ -1,16 +1,16 @@
-package world.phantasmal.observable.value.list
+package world.phantasmal.observable.cell.list
 
-import world.phantasmal.observable.value.MutableValTests
+import world.phantasmal.observable.cell.MutableCellTests
 import kotlin.test.Test
 import kotlin.test.assertEquals
 import kotlin.test.assertNull
 import kotlin.test.assertTrue
 
 /**
- * Test suite for all [MutableListVal] implementations. There is a subclass of this suite for every
+ * Test suite for all [MutableListCell] implementations. There is a subclass of this suite for every
- * [MutableListVal] implementation.
+ * [MutableListCell] implementation.
  */
-interface MutableListValTests<T : Any> : ListValTests, MutableValTests<List<T>> {
+interface MutableListCellTests<T : Any> : ListCellTests, MutableCellTests<List<T>> {
     override fun createProvider(): Provider<T>
 
     @Test
@@ -71,8 +71,8 @@ interface MutableListValTests<T : Any> : ListValTests, MutableValTests<List<T>>
         assertEquals(v3, c3.inserted[0])
     }
 
-    interface Provider<T : Any> : ListValTests.Provider, MutableValTests.Provider<List<T>> {
+    interface Provider<T : Any> : ListCellTests.Provider, MutableCellTests.Provider<List<T>> {
-        override val observable: MutableListVal<T>
+        override val observable: MutableListCell<T>
 
         fun createElement(): T
     }

observable/src/commonTest/kotlin/world/phantasmal/observable/cell/list/SimpleListCellTests.kt

@@ -1,13 +1,13 @@
-package world.phantasmal.observable.value.list
+package world.phantasmal.observable.cell.list
 
 import kotlin.test.Test
 import kotlin.test.assertEquals
 
-class SimpleListValTests : MutableListValTests<Int> {
+class SimpleListCellTests : MutableListCellTests<Int> {
-    override fun createProvider() = object : MutableListValTests.Provider<Int> {
+    override fun createProvider() = object : MutableListCellTests.Provider<Int> {
         private var nextElement = 0
 
-        override val observable = SimpleListVal(mutableListOf<Int>())
+        override val observable = SimpleListCell(mutableListOf<Int>())
 
         override fun addElement() {
             observable.add(createElement())
@@ -20,7 +20,7 @@ class SimpleListValTests : MutableListValTests<Int> {
 
     @Test
     fun instantiates_correctly() = test {
-        val list = SimpleListVal(mutableListOf(1, 2, 3))
+        val list = SimpleListCell(mutableListOf(1, 2, 3))
 
         assertEquals(3, list.size.value)
         assertEquals(3, list.value.size)

observable/src/commonTest/kotlin/world/phantasmal/observable/cell/list/StaticListCellTests.kt

@@ -1,14 +1,15 @@
-package world.phantasmal.observable.value.list
+package world.phantasmal.observable.cell.list
 
 import world.phantasmal.observable.test.ObservableTestSuite
 import kotlin.test.Test
 import kotlin.test.assertEquals
 
-class StaticListValTests : ObservableTestSuite {
+class StaticListCellTests : ObservableTestSuite {
     @Test
-    fun observing_StaticListVal_should_never_create_leaks() = test {
+    fun observing_StaticListCell_should_never_create_leaks() = test {
-        val static = StaticListVal(listOf(1, 2, 3))
+        val static = StaticListCell(listOf(1, 2, 3))
 
+        // We never call dispose on the returned disposables.
         static.observe {}
         static.observe(callNow = false) {}
         static.observe(callNow = true) {}
@@ -18,7 +19,7 @@ class StaticListValTests : ObservableTestSuite {
 
     @Test
     fun observe_respects_callNow() = test {
-        val static = StaticListVal(listOf(1, 2, 3))
+        val static = StaticListCell(listOf(1, 2, 3))
         var calls = 0
 
         static.observe(callNow = false) { calls++ }
@@ -29,7 +30,7 @@ class StaticListValTests : ObservableTestSuite {
 
     @Test
     fun observeList_respects_callNow() = test {
-        val static = StaticListVal(listOf(1, 2, 3))
+        val static = StaticListCell(listOf(1, 2, 3))
         var calls = 0
 
         static.observeList(callNow = false) { calls++ }

observable/src/commonTest/kotlin/world/phantasmal/observable/value/DelegatingValTests.kt

@@ -1,20 +0,0 @@
-package world.phantasmal.observable.value
-
-class DelegatingValTests : RegularValTests, MutableValTests<Int> {
-    override fun createProvider() = object : MutableValTests.Provider<Int> {
-        private var v = 0
-
-        override val observable = DelegatingVal({ v }, { v = it })
-
-        override fun emit() {
-            observable.value += 2
-        }
-
-        override fun createValue(): Int = v + 1
-    }
-
-    override fun <T> createWithValue(value: T): DelegatingVal<T> {
-        var v = value
-        return DelegatingVal({ v }, { v = it })
-    }
-}

observable/src/commonTest/kotlin/world/phantasmal/observable/value/DependentValTests.kt

@@ -1,18 +0,0 @@
-package world.phantasmal.observable.value
-
-class DependentValTests : RegularValTests {
-    override fun createProvider() = object : ValTests.Provider {
-        val v = SimpleVal(0)
-
-        override val observable = DependentVal(v) { 2 * v.value }
-
-        override fun emit() {
-            v.value += 2
-        }
-    }
-
-    override fun <T> createWithValue(value: T): DependentVal<T> {
-        val v = SimpleVal(value)
-        return DependentVal(v) { v.value }
-    }
-}

observable/src/commonTest/kotlin/world/phantasmal/observable/value/FlatteningDependentValDependentValEmitsTests.kt

@@ -1,50 +0,0 @@
-package world.phantasmal.observable.value
-
-import kotlin.test.Test
-import kotlin.test.assertEquals
-import kotlin.test.assertNull
-
-/**
- * In these tests the direct dependency of the [FlatteningDependentVal] changes.
- */
-class FlatteningDependentValDependentValEmitsTests : RegularValTests {
-    override fun createProvider() = object : ValTests.Provider {
-        val v = SimpleVal(StaticVal(5))
-
-        override val observable = FlatteningDependentVal(v) { v.value }
-
-        override fun emit() {
-            v.value = StaticVal(v.value.value + 5)
-        }
-    }
-
-    override fun <T> createWithValue(value: T): FlatteningDependentVal<T> {
-        val v = StaticVal(StaticVal(value))
-        return FlatteningDependentVal(v) { v.value }
-    }
-
-    /**
-     * This is a regression test, it's important that this exact sequence of statements stays the
-     * same.
-     */
-    @Test
-    fun emits_a_change_when_its_direct_val_dependency_changes() = test {
-        val v = SimpleVal(SimpleVal(7))
-        val fv = FlatteningDependentVal(v) { v.value }
-        var observedValue: Int? = null
-
-        disposer.add(
-            fv.observe { observedValue = it.value }
-        )
-
-        assertNull(observedValue)
-
-        v.value.value = 99
-
-        assertEquals(99, observedValue)
-
-        v.value = SimpleVal(7)
-
-        assertEquals(7, observedValue)
-    }
-}

observable/src/commonTest/kotlin/world/phantasmal/observable/value/FlatteningDependentValNestedValEmitsTests.kt

@@ -1,21 +0,0 @@
-package world.phantasmal.observable.value
-
-/**
- * In these tests the dependency of the [FlatteningDependentVal]'s direct dependency changes.
- */
-class FlatteningDependentValNestedValEmitsTests : RegularValTests {
-    override fun createProvider() = object : ValTests.Provider {
-        val v = StaticVal(SimpleVal(5))
-
-        override val observable = FlatteningDependentVal(v) { v.value }
-
-        override fun emit() {
-            v.value.value += 5
-        }
-    }
-
-    override fun <T> createWithValue(value: T): FlatteningDependentVal<T> {
-        val v = StaticVal(StaticVal(value))
-        return FlatteningDependentVal(v) { v.value }
-    }
-}

observable/src/commonTest/kotlin/world/phantasmal/observable/value/RegularValTests.kt

@@ -1,160 +0,0 @@
-package world.phantasmal.observable.value
-
-import kotlin.test.*
-
-/**
- * Test suite for all [Val] implementations that aren't ListVals. There is a subclass of this suite
- * for every non-ListVal [Val] implementation.
- */
-interface RegularValTests : ValTests {
-    fun <T> createWithValue(value: T): Val<T>
-
-    /**
-     * [Val.value] should correctly reflect changes even when the [Val] has no observers. Typically
-     * this means that the val's value is not updated in real time, only when it is queried.
-     */
-    @Test
-    fun reflects_changes_without_observers() = test {
-        val p = createProvider()
-
-        var old: Any?
-
-        repeat(5) {
-            // Value should change after emit.
-            old = p.observable.value
-
-            p.emit()
-
-            val new = p.observable.value
-
-            assertNotEquals(old, new)
-
-            // Value should not change when emit hasn't been called since the last access.
-            assertEquals(new, p.observable.value)
-
-            old = new
-        }
-    }
-
-    @Test
-    fun val_convenience_methods() = test {
-        listOf(Any(), null).forEach { any ->
-            val anyVal = createWithValue(any)
-
-            // Test the test setup first.
-            assertEquals(any, anyVal.value)
-
-            // Test `isNull`.
-            assertEquals(any == null, anyVal.isNull().value)
-
-            // Test `isNotNull`.
-            assertEquals(any != null, anyVal.isNotNull().value)
-        }
-    }
-
-    @Test
-    fun val_generic_extensions() = test {
-        listOf(Any(), null).forEach { any ->
-            val anyVal = createWithValue(any)
-
-            // Test the test setup first.
-            assertEquals(any, anyVal.value)
-
-            // Test `orElse`.
-            assertEquals(any ?: "default", anyVal.orElse { "default" }.value)
-        }
-
-        fun <T> testEqNe(a: T, b: T) {
-            val aVal = createWithValue(a)
-            val bVal = createWithValue(b)
-
-            // Test the test setup first.
-            assertEquals(a, aVal.value)
-            assertEquals(b, bVal.value)
-
-            // Test `eq`.
-            assertEquals(a == b, (aVal eq b).value)
-            assertEquals(a == b, (aVal eq bVal).value)
-
-            // Test `ne`.
-            assertEquals(a != b, (aVal ne b).value)
-            assertEquals(a != b, (aVal ne bVal).value)
-        }
-
-        testEqNe(10, 10)
-        testEqNe(5, 99)
-        testEqNe("a", "a")
-        testEqNe("x", "y")
-    }
-
-    @Test
-    fun val_comparable_extensions() = test {
-        fun <T : Comparable<T>> comparable_tests(a: T, b: T) {
-            val aVal = createWithValue(a)
-            val bVal = createWithValue(b)
-
-            // Test the test setup first.
-            assertEquals(a, aVal.value)
-            assertEquals(b, bVal.value)
-
-            // Test `gt`.
-            assertEquals(a > b, (aVal gt b).value)
-            assertEquals(a > b, (aVal gt bVal).value)
-
-            // Test `lt`.
-            assertEquals(a < b, (aVal lt b).value)
-            assertEquals(a < b, (aVal lt bVal).value)
-        }
-
-        comparable_tests(10, 10)
-        comparable_tests(7.0, 5.0)
-        comparable_tests((5000).toShort(), (7000).toShort())
-    }
-
-    @Test
-    fun val_boolean_extensions() = test {
-        listOf(true, false).forEach { bool ->
-            val boolVal = createWithValue(bool)
-
-            // Test the test setup first.
-            assertEquals(bool, boolVal.value)
-
-            // Test `and`.
-            assertEquals(bool, (boolVal and trueVal()).value)
-            assertFalse((boolVal and falseVal()).value)
-
-            // Test `or`.
-            assertTrue((boolVal or trueVal()).value)
-            assertEquals(bool, (boolVal or falseVal()).value)
-
-            // Test `xor`.
-            assertEquals(!bool, (boolVal xor trueVal()).value)
-            assertEquals(bool, (boolVal xor falseVal()).value)
-
-            // Test `!` (unary not).
-            assertEquals(!bool, (!boolVal).value)
-        }
-    }
-
-    @Test
-    fun val_string_extensions() = test {
-        listOf("", "  ", "\t\t", "non-empty-non-blank").forEach { string ->
-            val stringVal = createWithValue(string)
-
-            // Test the test setup first.
-            assertEquals(string, stringVal.value)
-
-            // Test `isEmpty`.
-            assertEquals(string.isEmpty(), stringVal.isEmpty().value)
-
-            // Test `isNotEmpty`.
-            assertEquals(string.isNotEmpty(), stringVal.isNotEmpty().value)
-
-            // Test `isBlank`.
-            assertEquals(string.isBlank(), stringVal.isBlank().value)
-
-            // Test `isNotBlank`.
-            assertEquals(string.isNotBlank(), stringVal.isNotBlank().value)
-        }
-    }
-}

observable/src/commonTest/kotlin/world/phantasmal/observable/value/SimpleValTests.kt

@@ -1,15 +0,0 @@
-package world.phantasmal.observable.value
-
-class SimpleValTests : RegularValTests, MutableValTests<Int> {
-    override fun createProvider() = object : MutableValTests.Provider<Int> {
-        override val observable = SimpleVal(1)
-
-        override fun emit() {
-            observable.value += 2
-        }
-
-        override fun createValue(): Int = observable.value + 1
-    }
-
-    override fun <T> createWithValue(value: T) = SimpleVal(value)
-}

observable/src/commonTest/kotlin/world/phantasmal/observable/value/ValCreationTests.kt

@@ -1,49 +0,0 @@
-package world.phantasmal.observable.value
-
-import world.phantasmal.observable.test.ObservableTestSuite
-import kotlin.test.*
-
-class ValCreationTests : ObservableTestSuite {
-    @Test
-    fun test_value() = test {
-        assertEquals(7, value(7).value)
-    }
-
-    @Test
-    fun test_trueVal() = test {
-        assertTrue(trueVal().value)
-    }
-
-    @Test
-    fun test_falseVal() = test {
-        assertFalse(falseVal().value)
-    }
-
-    @Test
-    fun test_nullVal() = test {
-        assertNull(nullVal().value)
-    }
-
-    @Test
-    fun test_mutableVal_with_initial_value() = test {
-        val v = mutableVal(17)
-
-        assertEquals(17, v.value)
-
-        v.value = 201
-
-        assertEquals(201, v.value)
-    }
-
-    @Test
-    fun test_mutableVal_with_getter_and_setter() = test {
-        var x = 17
-        val v = mutableVal({ x }, { x = it })
-
-        assertEquals(17, v.value)
-
-        v.value = 201
-
-        assertEquals(201, v.value)
-    }
-}

observable/src/commonTest/kotlin/world/phantasmal/observable/value/list/DependentListValTests.kt

@@ -1,13 +0,0 @@
-package world.phantasmal.observable.value.list
-
-class DependentListValTests : ListValTests {
-    override fun createProvider() = object : ListValTests.Provider {
-        private val l = SimpleListVal<Int>(mutableListOf())
-
-        override val observable = DependentListVal(l) { l.value.map { 2 * it } }
-
-        override fun addElement() {
-            l.add(4)
-        }
-    }
-}

observable/src/commonTest/kotlin/world/phantasmal/observable/value/list/FlatteningDependentListValDependentValEmitsTests.kt

@@ -1,25 +0,0 @@
-package world.phantasmal.observable.value.list
-
-import world.phantasmal.observable.value.SimpleVal
-
-/**
- * In these tests the direct dependency of the [FlatteningDependentListVal] changes.
- */
-class FlatteningDependentListValDependentValEmitsTests : ListValTests {
-    override fun createProvider() = object : ListValTests.Provider {
-        // The nested val can't change.
-        private val nestedVal = StaticListVal<Int>(emptyList())
-
-        // The direct dependency of the list under test can change.
-        private val dependencyVal = SimpleVal<ListVal<Int>>(nestedVal)
-
-        override val observable =
-            FlatteningDependentListVal(dependencyVal) { dependencyVal.value }
-
-        override fun addElement() {
-            // Update the direct dependency.
-            val oldNestedVal: ListVal<Int> = dependencyVal.value
-            dependencyVal.value = StaticListVal(oldNestedVal.value + 4)
-        }
-    }
-}

observable/src/commonTest/kotlin/world/phantasmal/observable/value/list/FlatteningDependentListValNestedValEmitsTests.kt

@@ -1,24 +0,0 @@
-package world.phantasmal.observable.value.list
-
-import world.phantasmal.observable.value.StaticVal
-
-/**
- * In these tests the dependency of the [FlatteningDependentListVal]'s direct dependency changes.
- */
-class FlatteningDependentListValNestedValEmitsTests : ListValTests {
-    override fun createProvider() = object : ListValTests.Provider {
-        // The nested val can change.
-        private val nestedVal = SimpleListVal(mutableListOf<Int>())
-
-        // The direct dependency of the list under test can't change.
-        private val dependentVal = StaticVal<ListVal<Int>>(nestedVal)
-
-        override val observable =
-            FlatteningDependentListVal(dependentVal) { dependentVal.value }
-
-        override fun addElement() {
-            // Update the nested dependency.
-            nestedVal.add(4)
-        }
-    }
-}

web/src/main/kotlin/world/phantasmal/web/Main.kt

@@ -15,7 +15,7 @@ import world.phantasmal.core.disposable.Disposable
 import world.phantasmal.core.disposable.Disposer
 import world.phantasmal.core.disposable.TrackedDisposable
 import world.phantasmal.core.disposable.disposable
-import world.phantasmal.observable.value.mutableVal
+import world.phantasmal.observable.cell.mutableCell
 import world.phantasmal.web.application.Application
 import world.phantasmal.web.core.loading.AssetLoader
 import world.phantasmal.web.core.rendering.DisposableThreeRenderer
@@ -90,7 +90,7 @@ private fun createThreeRenderer(canvas: HTMLCanvasElement): DisposableThreeRende
 private class HistoryApplicationUrl : TrackedDisposable(), ApplicationUrl {
     private val path: String get() = window.location.pathname
 
-    override val url = mutableVal(window.location.hash.substring(1))
+    override val url = mutableCell(window.location.hash.substring(1))
 
     private val popStateListener = window.disposableListener<PopStateEvent>("popstate", {
         url.value = window.location.hash.substring(1)

web/src/main/kotlin/world/phantasmal/web/application/controllers/MainContentController.kt

@@ -1,10 +1,10 @@
 package world.phantasmal.web.application.controllers
 
-import world.phantasmal.observable.value.Val
+import world.phantasmal.observable.cell.Cell
 import world.phantasmal.web.core.PwToolType
 import world.phantasmal.web.core.stores.UiStore
 import world.phantasmal.webui.controllers.Controller
 
 class MainContentController(uiStore: UiStore) : Controller() {
-    val tools: Map<PwToolType, Val<Boolean>> = uiStore.toolToActive
+    val tools: Map<PwToolType, Cell<Boolean>> = uiStore.toolToActive
 }

web/src/main/kotlin/world/phantasmal/web/application/controllers/NavigationController.kt

@@ -4,19 +4,19 @@ import kotlinx.browser.window
 import kotlinx.datetime.Clock
 import kotlinx.datetime.TimeZone
 import kotlinx.datetime.toLocalDateTime
-import world.phantasmal.observable.value.Val
+import world.phantasmal.observable.cell.Cell
-import world.phantasmal.observable.value.mutableVal
+import world.phantasmal.observable.cell.mutableCell
 import world.phantasmal.web.core.PwToolType
 import world.phantasmal.web.core.stores.UiStore
 import world.phantasmal.webui.controllers.Controller
 import kotlin.math.floor
 
 class NavigationController(private val uiStore: UiStore, private val clock: Clock) : Controller() {
-    private val _internetTime = mutableVal("@")
+    private val _internetTime = mutableCell("@")
     private var internetTimeInterval: Int
 
-    val tools: Map<PwToolType, Val<Boolean>> = uiStore.toolToActive
+    val tools: Map<PwToolType, Cell<Boolean>> = uiStore.toolToActive
-    val internetTime: Val<String> = _internetTime
+    val internetTime: Cell<String> = _internetTime
 
     init {
         internetTimeInterval = window.setInterval(::updateInternetTime, 1000)

web/src/main/kotlin/world/phantasmal/web/application/widgets/NavigationWidget.kt

@@ -1,11 +1,12 @@
 package world.phantasmal.web.application.widgets
 
 import org.w3c.dom.Node
-import world.phantasmal.observable.value.falseVal
+import world.phantasmal.observable.cell.cell
-import world.phantasmal.observable.value.list.listVal
+import world.phantasmal.observable.cell.falseCell
-import world.phantasmal.observable.value.value
+import world.phantasmal.observable.cell.list.listCell
 import world.phantasmal.web.application.controllers.NavigationController
 import world.phantasmal.web.core.dom.externalLink
+import world.phantasmal.web.core.models.Server
 import world.phantasmal.webui.dom.Icon
 import world.phantasmal.webui.dom.div
 import world.phantasmal.webui.dom.icon
@@ -29,11 +30,11 @@ class NavigationWidget(private val ctrl: NavigationController) : Widget() {
                 className = "pw-application-navigation-right"
 
                 val serverSelect = Select(
-                    enabled = falseVal(),
+                    enabled = falseCell(),
                     label = "Server:",
-                    items = listVal("Ephinea"),
+                    items = listCell(Server.Ephinea.uiName),
-                    selected = value("Ephinea"),
+                    selected = cell(Server.Ephinea.uiName),
-                    tooltip = value("Only Ephinea is supported at the moment"),
+                    tooltip = cell("Only ${Server.Ephinea.uiName} is supported at the moment"),
                 )
                 addChild(serverSelect.label!!)
                 addChild(serverSelect)

web/src/main/kotlin/world/phantasmal/web/application/widgets/PwToolButton.kt

@@ -2,8 +2,8 @@ package world.phantasmal.web.application.widgets
 
 import org.w3c.dom.Node
 import world.phantasmal.observable.Observable
-import world.phantasmal.observable.value.nullVal
+import world.phantasmal.observable.cell.nullCell
-import world.phantasmal.observable.value.trueVal
+import world.phantasmal.observable.cell.trueCell
 import world.phantasmal.web.core.PwToolType
 import world.phantasmal.webui.dom.input
 import world.phantasmal.webui.dom.label
@@ -14,7 +14,7 @@ class PwToolButton(
     private val tool: PwToolType,
     private val toggled: Observable<Boolean>,
     private val onMouseDown: () -> Unit,
-) : Control(visible = trueVal(), enabled = trueVal(), tooltip = nullVal()) {
+) : Control(visible = trueCell(), enabled = trueCell(), tooltip = nullCell()) {
     private val inputId = "pw-application-pw-tool-button-${tool.name.toLowerCase()}"
 
     override fun Node.createElement() =

web/src/main/kotlin/world/phantasmal/web/core/stores/UiStore.kt

@@ -6,17 +6,17 @@ import org.w3c.dom.events.KeyboardEvent
 import world.phantasmal.core.disposable.Disposable
 import world.phantasmal.core.disposable.Disposer
 import world.phantasmal.core.disposable.disposable
-import world.phantasmal.observable.value.MutableVal
+import world.phantasmal.observable.cell.Cell
-import world.phantasmal.observable.value.Val
+import world.phantasmal.observable.cell.MutableCell
-import world.phantasmal.observable.value.eq
+import world.phantasmal.observable.cell.eq
-import world.phantasmal.observable.value.mutableVal
+import world.phantasmal.observable.cell.mutableCell
 import world.phantasmal.web.core.PwToolType
 import world.phantasmal.web.core.models.Server
 import world.phantasmal.webui.dom.disposableListener
 import world.phantasmal.webui.stores.Store
 
 interface ApplicationUrl {
-    val url: Val<String>
+    val url: Cell<String>
 
     fun pushUrl(url: String)
 
@@ -24,16 +24,16 @@ interface ApplicationUrl {
 }
 
 class UiStore(private val applicationUrl: ApplicationUrl) : Store() {
-    private val _currentTool: MutableVal<PwToolType>
+    private val _currentTool: MutableCell<PwToolType>
 
-    private val _path = mutableVal("")
+    private val _path = mutableCell("")
-    private val _server = mutableVal(Server.Ephinea)
+    private val _server = mutableCell(Server.Ephinea)
 
     /**
      * Maps full paths to maps of parameters and their values. In other words we keep track of
      * parameter values per [applicationUrl].
      */
-    private val parameters: MutableMap<String, MutableMap<String, MutableVal<String?>>> =
+    private val parameters: MutableMap<String, MutableMap<String, MutableCell<String?>>> =
         mutableMapOf()
     private val globalKeyDownHandlers: MutableMap<String, suspend (e: KeyboardEvent) -> Unit> =
         mutableMapOf()
@@ -55,32 +55,28 @@ class UiStore(private val applicationUrl: ApplicationUrl) : Store() {
     /**
      * The tool that is currently visible.
      */
-    val currentTool: Val<PwToolType>
+    val currentTool: Cell<PwToolType>
 
     /**
-     * Map of tools to a boolean Val that says whether they are the current tool or not.
+     * Map of tools to a boolean cell that says whether they are the current tool or not.
      */
-    val toolToActive: Map<PwToolType, Val<Boolean>>
+    val toolToActive: Map<PwToolType, Cell<Boolean>>
 
     /**
      * Application URL without the tool path prefix.
      */
-    val path: Val<String> = _path
+    val path: Cell<String> = _path
 
     /**
      * The private server we're currently showing data and tools for.
      */
-    val server: Val<Server> = _server
+    val server: Cell<Server> = _server
 
     init {
-        _currentTool = mutableVal(defaultTool)
+        _currentTool = mutableCell(defaultTool)
         currentTool = _currentTool
 
-        toolToActive = tools
+        toolToActive = tools.associateWith { tool -> currentTool eq tool }
-            .map { tool ->
-                tool to (currentTool eq tool)
-            }
-            .toMap()
 
         addDisposables(
             window.disposableListener("keydown", ::dispatchGlobalKeyDown),
@@ -111,7 +107,7 @@ class UiStore(private val applicationUrl: ApplicationUrl) : Store() {
         path: String,
         parameter: String,
         setInitialValue: (String?) -> Unit,
-        value: Val<String?>,
+        value: Cell<String?>,
         onChange: (String?) -> Unit,
     ): Disposable {
         require(parameter !== FEATURES_PARAM) {
@@ -119,7 +115,7 @@ class UiStore(private val applicationUrl: ApplicationUrl) : Store() {
         }
 
         val pathParams = parameters.getOrPut("/${tool.slug}$path", ::mutableMapOf)
-        val param = pathParams.getOrPut(parameter) { mutableVal(null) }
+        val param = pathParams.getOrPut(parameter) { mutableCell(null) }
 
         setInitialValue(param.value)
 
@@ -142,7 +138,7 @@ class UiStore(private val applicationUrl: ApplicationUrl) : Store() {
     private fun setParameter(
         tool: PwToolType,
         path: String,
-        parameter: MutableVal<String?>,
+        parameter: MutableCell<String?>,
         value: String?,
         replaceUrl: Boolean,
     ) {
@@ -194,7 +190,7 @@ class UiStore(private val applicationUrl: ApplicationUrl) : Store() {
                         features.add(feature)
                     }
                 } else {
-                    params.getOrPut(param) { mutableVal(value) }.value = value
+                    params.getOrPut(param) { mutableCell(value) }.value = value
                 }
             }
         }
@@ -262,6 +258,6 @@ class UiStore(private val applicationUrl: ApplicationUrl) : Store() {
     companion object {
         private const val FEATURES_PARAM = "features"
         private val SLUG_TO_PW_TOOL: Map<String, PwToolType> =
-            PwToolType.values().map { it.slug to it }.toMap()
+            PwToolType.values().associateBy { it.slug }
     }
 }

web/src/main/kotlin/world/phantasmal/web/core/undo/Undo.kt

@@ -1,28 +1,28 @@
 package world.phantasmal.web.core.undo
 
-import world.phantasmal.observable.value.Val
+import world.phantasmal.observable.cell.Cell
 import world.phantasmal.web.core.actions.Action
 
 interface Undo {
-    val canUndo: Val<Boolean>
+    val canUndo: Cell<Boolean>
-    val canRedo: Val<Boolean>
+    val canRedo: Cell<Boolean>
 
     /**
      * The first action that will be undone when calling undo().
      */
-    val firstUndo: Val<Action?>
+    val firstUndo: Cell<Action?>
 
     /**
      * The first action that will be redone when calling redo().
      */
-    val firstRedo: Val<Action?>
+    val firstRedo: Cell<Action?>
 
     /**
      * True if this undo is at the point in time where the last save happened. See [savePoint].
      * If false, it should be safe to leave the application because no changes have happened since
      * the last save point (either because there were no changes or all changes have been undone).
      */
-    val atSavePoint: Val<Boolean>
+    val atSavePoint: Cell<Boolean>
 
     fun undo(): Boolean
     fun redo(): Boolean

web/src/main/kotlin/world/phantasmal/web/core/undo/UndoManager.kt

@@ -1,25 +1,25 @@
 package world.phantasmal.web.core.undo
 
-import world.phantasmal.observable.value.*
+import world.phantasmal.observable.cell.*
-import world.phantasmal.observable.value.list.mutableListVal
+import world.phantasmal.observable.cell.list.mutableListCell
 import world.phantasmal.web.core.actions.Action
 
 class UndoManager {
-    private val undos = mutableListVal<Undo>(NopUndo) { arrayOf(it.atSavePoint) }
+    private val undos = mutableListCell<Undo>(NopUndo) { arrayOf(it.atSavePoint) }
-    private val _current = mutableVal<Undo>(NopUndo)
+    private val _current = mutableCell<Undo>(NopUndo)
 
-    val current: Val<Undo> = _current
+    val current: Cell<Undo> = _current
 
-    val canUndo: Val<Boolean> = current.flatMap { it.canUndo }
+    val canUndo: Cell<Boolean> = current.flatMap { it.canUndo }
-    val canRedo: Val<Boolean> = current.flatMap { it.canRedo }
+    val canRedo: Cell<Boolean> = current.flatMap { it.canRedo }
-    val firstUndo: Val<Action?> = current.flatMap { it.firstUndo }
+    val firstUndo: Cell<Action?> = current.flatMap { it.firstUndo }
-    val firstRedo: Val<Action?> = current.flatMap { it.firstRedo }
+    val firstRedo: Cell<Action?> = current.flatMap { it.firstRedo }
 
     /**
      * True if all undos are at the most recent save point. I.e., true if there are no changes to
      * save.
      */
-    val allAtSavePoint: Val<Boolean> = undos.all { it.atSavePoint.value }
+    val allAtSavePoint: Cell<Boolean> = undos.all { it.atSavePoint.value }
 
     fun addUndo(undo: Undo) {
         undos.add(undo)
@@ -56,11 +56,11 @@ class UndoManager {
     }
 
     private object NopUndo : Undo {
-        override val canUndo = falseVal()
+        override val canUndo = falseCell()
-        override val canRedo = falseVal()
+        override val canRedo = falseCell()
-        override val firstUndo = nullVal()
+        override val firstUndo = nullCell()
-        override val firstRedo = nullVal()
+        override val firstRedo = nullCell()
-        override val atSavePoint = trueVal()
+        override val atSavePoint = trueCell()
 
         override fun undo(): Boolean = false
 

web/src/main/kotlin/world/phantasmal/web/core/undo/UndoStack.kt

@@ -1,32 +1,32 @@
 package world.phantasmal.web.core.undo
 
-import world.phantasmal.observable.value.*
+import world.phantasmal.observable.cell.*
-import world.phantasmal.observable.value.list.mutableListVal
+import world.phantasmal.observable.cell.list.mutableListCell
 import world.phantasmal.web.core.actions.Action
 
 /**
  * Full-fledged linear undo/redo implementation.
  */
 class UndoStack(manager: UndoManager) : Undo {
-    private val stack = mutableListVal<Action>()
+    private val stack = mutableListCell<Action>()
 
     /**
      * The index where new actions are inserted. If not equal to the [stack]'s size, points to the
      * action that will be redone when calling [redo].
      */
-    private val index = mutableVal(0)
+    private val index = mutableCell(0)
-    private val savePointIndex = mutableVal(0)
+    private val savePointIndex = mutableCell(0)
     private var undoingOrRedoing = false
 
-    override val canUndo: Val<Boolean> = index gt 0
+    override val canUndo: Cell<Boolean> = index gt 0
 
-    override val canRedo: Val<Boolean> = map(stack, index) { stack, index -> index < stack.size }
+    override val canRedo: Cell<Boolean> = map(stack, index) { stack, index -> index < stack.size }
 
-    override val firstUndo: Val<Action?> = index.map { stack.value.getOrNull(it - 1) }
+    override val firstUndo: Cell<Action?> = index.map { stack.value.getOrNull(it - 1) }
 
-    override val firstRedo: Val<Action?> = index.map { stack.value.getOrNull(it) }
+    override val firstRedo: Cell<Action?> = index.map { stack.value.getOrNull(it) }
 
-    override val atSavePoint: Val<Boolean> = index eq savePointIndex
+    override val atSavePoint: Cell<Boolean> = index eq savePointIndex
 
     init {
         manager.addUndo(this)

web/src/main/kotlin/world/phantasmal/web/core/widgets/DockWidget.kt

@@ -3,8 +3,8 @@ package world.phantasmal.web.core.widgets
 import kotlinx.coroutines.launch
 import mu.KotlinLogging
 import org.w3c.dom.Node
-import world.phantasmal.observable.value.Val
+import world.phantasmal.observable.cell.Cell
-import world.phantasmal.observable.value.trueVal
+import world.phantasmal.observable.cell.trueCell
 import world.phantasmal.web.core.controllers.*
 import world.phantasmal.web.externals.goldenLayout.GoldenLayout
 import world.phantasmal.webui.dom.div
@@ -14,7 +14,7 @@ import world.phantasmal.webui.widgets.Widget
 private val logger = KotlinLogging.logger {}
 
 class DockWidget(
-    visible: Val<Boolean> = trueVal(),
+    visible: Cell<Boolean> = trueCell(),
     private val ctrl: DockController,
     private val createWidget: (id: String) -> Widget,
 ) : Widget(visible) {

web/src/main/kotlin/world/phantasmal/web/core/widgets/UnavailableWidget.kt

@@ -1,22 +1,22 @@
 package world.phantasmal.web.core.widgets
 
 import org.w3c.dom.Node
-import world.phantasmal.observable.value.Val
+import world.phantasmal.observable.cell.Cell
-import world.phantasmal.observable.value.falseVal
+import world.phantasmal.observable.cell.falseCell
-import world.phantasmal.observable.value.trueVal
+import world.phantasmal.observable.cell.trueCell
 import world.phantasmal.webui.dom.div
 import world.phantasmal.webui.widgets.Label
 import world.phantasmal.webui.widgets.Widget
 
 class UnavailableWidget(
-    visible: Val<Boolean> = trueVal(),
+    visible: Cell<Boolean> = trueCell(),
     private val message: String,
 ) : Widget(visible) {
     override fun Node.createElement() =
         div {
             className = "pw-core-unavailable"
 
-            addWidget(Label(enabled = falseVal(), text = message))
+            addWidget(Label(enabled = falseCell(), text = message))
         }
 
     companion object {

web/src/main/kotlin/world/phantasmal/web/huntOptimizer/controllers/MethodsForEpisodeController.kt

@@ -2,9 +2,9 @@ package world.phantasmal.web.huntOptimizer.controllers
 
 import world.phantasmal.lib.Episode
 import world.phantasmal.lib.fileFormats.quest.NpcType
-import world.phantasmal.observable.value.list.ListVal
+import world.phantasmal.observable.cell.list.ListCell
-import world.phantasmal.observable.value.list.listVal
+import world.phantasmal.observable.cell.list.listCell
-import world.phantasmal.observable.value.list.mutableListVal
+import world.phantasmal.observable.cell.list.mutableListCell
 import world.phantasmal.web.huntOptimizer.models.HuntMethodModel
 import world.phantasmal.web.huntOptimizer.stores.HuntMethodStore
 import world.phantasmal.webui.controllers.Column
@@ -17,14 +17,14 @@ class MethodsForEpisodeController(
     private val huntMethodStore: HuntMethodStore,
     episode: Episode,
 ) : TableController<HuntMethodModel>() {
-    private val methods = mutableListVal<HuntMethodModel>()
+    private val methods = mutableListCell<HuntMethodModel>()
     private val enemies: List<NpcType> = NpcType.VALUES.filter { it.enemy && it.episode == episode }
 
     override val fixedColumns = 2
 
-    override val values: ListVal<HuntMethodModel> = methods
+    override val values: ListCell<HuntMethodModel> = methods
 
-    override val columns: ListVal<Column<HuntMethodModel>> = listVal(
+    override val columns: ListCell<Column<HuntMethodModel>> = listCell(
         Column(
             key = METHOD_COL_KEY,
             title = "Method",

web/src/main/kotlin/world/phantasmal/web/huntOptimizer/controllers/OptimizationResultController.kt

@@ -1,7 +1,7 @@
 package world.phantasmal.web.huntOptimizer.controllers
 
-import world.phantasmal.observable.value.list.ListVal
+import world.phantasmal.observable.cell.cell
-import world.phantasmal.observable.value.value
+import world.phantasmal.observable.cell.list.ListCell
 import world.phantasmal.web.huntOptimizer.models.OptimalMethodModel
 import world.phantasmal.web.huntOptimizer.stores.HuntOptimizerStore
 import world.phantasmal.webui.controllers.Column
@@ -15,11 +15,11 @@ class OptimizationResultController(
     override val fixedColumns = 4
     override val hasFooter = true
 
-    override val values: ListVal<OptimalMethodModel> =
+    override val values: ListCell<OptimalMethodModel> =
-        huntOptimizerStore.optimizationResult.mapToListVal { it.optimalMethods }
+        huntOptimizerStore.optimizationResult.mapToList { it.optimalMethods }
 
-    override val columns: ListVal<Column<OptimalMethodModel>> =
+    override val columns: ListCell<Column<OptimalMethodModel>> =
-        huntOptimizerStore.optimizationResult.mapToListVal { result ->
+        huntOptimizerStore.optimizationResult.mapToList { result ->
             var totalRuns = .0
             var totalTime = Duration.ZERO
 
@@ -33,7 +33,7 @@ class OptimizationResultController(
                     key = DIFF_COL,
                     title = "Difficulty",
                     width = 80,
-                    footer = value("Totals:"),
+                    footer = cell("Totals:"),
                 ),
                 Column(
                     key = METHOD_COL,
@@ -62,8 +62,8 @@ class OptimizationResultController(
                     width = 60,
                     textAlign = "right",
                     tooltip = { it.runs.toString() },
-                    footer = value(totalRuns.toRoundedString(1)),
+                    footer = cell(totalRuns.toRoundedString(1)),
-                    footerTooltip = value(totalRuns.toString()),
+                    footerTooltip = cell(totalRuns.toString()),
                 ),
                 Column(
                     key = TOTAL_TIME_COL,
@@ -71,8 +71,8 @@ class OptimizationResultController(
                     width = 60,
                     textAlign = "right",
                     tooltip = { it.totalTime.inHours.toString() },
-                    footer = value(totalTime.inHours.toRoundedString(1)),
+                    footer = cell(totalTime.inHours.toRoundedString(1)),
-                    footerTooltip = value(totalTime.inHours.toString()),
+                    footerTooltip = cell(totalTime.inHours.toString()),
                 ),
                 *Array(result.wantedItems.size) { index ->
                     val wanted = result.wantedItems[index]
@@ -86,8 +86,8 @@ class OptimizationResultController(
                         width = 80,
                         textAlign = "right",
                         tooltip = { it.itemTypeIdToCount[wanted.id]?.toString() },
-                        footer = value(totalCount.toRoundedString(2)),
+                        footer = cell(totalCount.toRoundedString(2)),
-                        footerTooltip = value(totalCount.toString()),
+                        footerTooltip = cell(totalCount.toString()),
                     )
                 },
             )

web/src/main/kotlin/world/phantasmal/web/huntOptimizer/controllers/WantedItemsController.kt

@@ -1,9 +1,9 @@
 package world.phantasmal.web.huntOptimizer.controllers
 
-import world.phantasmal.observable.value.MutableVal
+import world.phantasmal.observable.cell.Cell
-import world.phantasmal.observable.value.Val
+import world.phantasmal.observable.cell.MutableCell
-import world.phantasmal.observable.value.list.ListVal
+import world.phantasmal.observable.cell.list.ListCell
-import world.phantasmal.observable.value.mutableVal
+import world.phantasmal.observable.cell.mutableCell
 import world.phantasmal.web.huntOptimizer.models.WantedItemModel
 import world.phantasmal.web.huntOptimizer.stores.HuntOptimizerStore
 import world.phantasmal.web.shared.dto.ItemType
@@ -12,14 +12,14 @@ import world.phantasmal.webui.controllers.Controller
 class WantedItemsController(
     private val huntOptimizerStore: HuntOptimizerStore,
 ) : Controller() {
-    private val selectableItemsFilter: MutableVal<(ItemType) -> Boolean> = mutableVal { true }
+    private val selectableItemsFilter: MutableCell<(ItemType) -> Boolean> = mutableCell { true }
 
-    // TODO: Use ListVal.filtered with a Val when this is supported.
+    // TODO: Use ListCell.filtered with a Cell when this is supported.
-    val selectableItems: Val<List<ItemType>> = selectableItemsFilter.flatMap { filter ->
+    val selectableItems: Cell<List<ItemType>> = selectableItemsFilter.flatMap { filter ->
         huntOptimizerStore.huntableItems.filtered(filter)
     }
 
-    val wantedItems: ListVal<WantedItemModel> = huntOptimizerStore.wantedItems
+    val wantedItems: ListCell<WantedItemModel> = huntOptimizerStore.wantedItems
 
     fun filterSelectableItems(text: String) {
         val sanitized = text.trim()

web/src/main/kotlin/world/phantasmal/web/huntOptimizer/models/HuntMethodModel.kt

@@ -2,9 +2,9 @@ package world.phantasmal.web.huntOptimizer.models
 
 import world.phantasmal.lib.Episode
 import world.phantasmal.lib.fileFormats.quest.NpcType
-import world.phantasmal.observable.value.Val
+import world.phantasmal.observable.cell.Cell
-import world.phantasmal.observable.value.mutableVal
+import world.phantasmal.observable.cell.mutableCell
-import world.phantasmal.observable.value.orElse
+import world.phantasmal.observable.cell.orElse
 import kotlin.time.Duration
 
 class HuntMethodModel(
@@ -16,7 +16,7 @@ class HuntMethodModel(
      */
     val defaultTime: Duration,
 ) {
-    private val _userTime = mutableVal<Duration?>(null)
+    private val _userTime = mutableCell<Duration?>(null)
 
     val episode: Episode = quest.episode
 
@@ -25,9 +25,9 @@ class HuntMethodModel(
     /**
      * The time it takes to complete the quest in hours as specified by the user.
      */
-    val userTime: Val<Duration?> = _userTime
+    val userTime: Cell<Duration?> = _userTime
 
-    val time: Val<Duration> = userTime.orElse { defaultTime }
+    val time: Cell<Duration> = userTime.orElse { defaultTime }
 
     fun setUserTime(userTime: Duration?) {
         _userTime.value = userTime

web/src/main/kotlin/world/phantasmal/web/huntOptimizer/models/WantedItemModel.kt

@@ -1,13 +1,13 @@
 package world.phantasmal.web.huntOptimizer.models
 
-import world.phantasmal.observable.value.Val
+import world.phantasmal.observable.cell.Cell
-import world.phantasmal.observable.value.mutableVal
+import world.phantasmal.observable.cell.mutableCell
 import world.phantasmal.web.shared.dto.ItemType
 
 class WantedItemModel(val itemType: ItemType, amount: Int) {
-    private val _amount = mutableVal(0)
+    private val _amount = mutableCell(0)
 
-    val amount: Val<Int> = _amount
+    val amount: Cell<Int> = _amount
 
     init {
         setAmount(amount)

web/src/main/kotlin/world/phantasmal/web/huntOptimizer/stores/HuntMethodStore.kt

@@ -5,8 +5,8 @@ import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
 import world.phantasmal.lib.Episode
 import world.phantasmal.lib.fileFormats.quest.NpcType
-import world.phantasmal.observable.value.list.ListVal
+import world.phantasmal.observable.cell.list.ListCell
-import world.phantasmal.observable.value.list.mutableListVal
+import world.phantasmal.observable.cell.list.mutableListCell
 import world.phantasmal.web.core.loading.AssetLoader
 import world.phantasmal.web.core.models.Server
 import world.phantasmal.web.core.stores.UiStore
@@ -26,9 +26,9 @@ class HuntMethodStore(
     private val assetLoader: AssetLoader,
     private val huntMethodPersister: HuntMethodPersister,
 ) : Store() {
-    private val _methods = mutableListVal<HuntMethodModel> { arrayOf(it.time) }
+    private val _methods = mutableListCell<HuntMethodModel> { arrayOf(it.time) }
 
-    val methods: ListVal<HuntMethodModel> by lazy {
+    val methods: ListCell<HuntMethodModel> by lazy {
         observe(uiStore.server) { loadMethods(it) }
         _methods
     }

web/src/main/kotlin/world/phantasmal/web/huntOptimizer/stores/HuntOptimizerStore.kt

@@ -7,10 +7,10 @@ import mu.KotlinLogging
 import world.phantasmal.core.*
 import world.phantasmal.core.unsafe.UnsafeMap
 import world.phantasmal.lib.fileFormats.quest.NpcType
-import world.phantasmal.observable.value.Val
+import world.phantasmal.observable.cell.Cell
-import world.phantasmal.observable.value.list.ListVal
+import world.phantasmal.observable.cell.list.ListCell
-import world.phantasmal.observable.value.list.mutableListVal
+import world.phantasmal.observable.cell.list.mutableListCell
-import world.phantasmal.observable.value.mutableVal
+import world.phantasmal.observable.cell.mutableCell
 import world.phantasmal.web.core.models.Server
 import world.phantasmal.web.core.stores.EnemyDropTable
 import world.phantasmal.web.core.stores.ItemDropStore
@@ -44,11 +44,11 @@ class HuntOptimizerStore(
     private val itemTypeStore: ItemTypeStore,
     private val itemDropStore: ItemDropStore,
 ) : Store() {
-    private val _huntableItems = mutableListVal<ItemType>()
+    private val _huntableItems = mutableListCell<ItemType>()
-    private val _wantedItems = mutableListVal<WantedItemModel> { arrayOf(it.amount) }
+    private val _wantedItems = mutableListCell<WantedItemModel> { arrayOf(it.amount) }
-    private val _optimizationResult = mutableVal(OptimizationResultModel(emptyList(), emptyList()))
+    private val _optimizationResult = mutableCell(OptimizationResultModel(emptyList(), emptyList()))
 
-    val huntableItems: ListVal<ItemType> by lazy {
+    val huntableItems: ListCell<ItemType> by lazy {
         observe(uiStore.server) { server ->
             _huntableItems.clear()
 
@@ -64,12 +64,12 @@ class HuntOptimizerStore(
         _huntableItems
     }
 
-    val wantedItems: ListVal<WantedItemModel> by lazy {
+    val wantedItems: ListCell<WantedItemModel> by lazy {
         observe(uiStore.server) { loadWantedItems(it) }
         _wantedItems
     }
 
-    val optimizationResult: Val<OptimizationResultModel> = _optimizationResult
+    val optimizationResult: Cell<OptimizationResultModel> = _optimizationResult
 
     init {
         observe(wantedItems) {

web/src/main/kotlin/world/phantasmal/web/questEditor/QuestRunner.kt

@@ -1,14 +1,14 @@
 package world.phantasmal.web.questEditor
 
-import world.phantasmal.observable.value.Val
+import world.phantasmal.observable.cell.Cell
-import world.phantasmal.observable.value.falseVal
+import world.phantasmal.observable.cell.falseCell
 
 /**
  * Orchestrates everything related to emulating a quest run. Drives a VirtualMachine and
  * delegates to Debugger.
  */
 class QuestRunner {
-    val running: Val<Boolean> = falseVal()
+    val running: Cell<Boolean> = falseCell()
 
     fun stop() {
         // TODO

web/src/main/kotlin/world/phantasmal/web/questEditor/asm/AsmAnalyser.kt

@@ -11,9 +11,9 @@ import mu.KotlinLogging
 import org.w3c.dom.Worker
 import world.phantasmal.observable.ChangeEvent
 import world.phantasmal.observable.Observable
+import world.phantasmal.observable.cell.list.ListCell
+import world.phantasmal.observable.cell.list.mutableListCell
 import world.phantasmal.observable.emitter
-import world.phantasmal.observable.value.list.ListVal
-import world.phantasmal.observable.value.list.mutableListVal
 import world.phantasmal.web.shared.JSON_FORMAT
 import world.phantasmal.web.shared.messages.*
 import kotlin.coroutines.Continuation
@@ -24,7 +24,7 @@ private val logger = KotlinLogging.logger {}
 class AsmAnalyser {
     private var inlineStackArgs: Boolean = true
     private var _mapDesignations = emitter<Map<Int, Int>>()
-    private val _problems = mutableListVal<AssemblyProblem>()
+    private val _problems = mutableListCell<AssemblyProblem>()
 
     private val worker = Worker("/assembly-worker.js")
     private var nextRequestId = atomic(0)
@@ -35,7 +35,7 @@ class AsmAnalyser {
     private val inFlightRequests = mutableMapOf<Int, CancellableContinuation<*>>()
 
     val mapDesignations: Observable<Map<Int, Int>> = _mapDesignations
-    val problems: ListVal<AssemblyProblem> = _problems
+    val problems: ListCell<AssemblyProblem> = _problems
 
     init {
         worker.onmessage = { e ->

web/src/main/kotlin/world/phantasmal/web/questEditor/controllers/AsmEditorController.kt

@@ -1,27 +1,27 @@
 package world.phantasmal.web.questEditor.controllers
 
 import world.phantasmal.observable.Observable
-import world.phantasmal.observable.value.Val
+import world.phantasmal.observable.cell.Cell
-import world.phantasmal.observable.value.not
+import world.phantasmal.observable.cell.not
-import world.phantasmal.observable.value.or
+import world.phantasmal.observable.cell.or
-import world.phantasmal.observable.value.orElse
+import world.phantasmal.observable.cell.orElse
 import world.phantasmal.web.externals.monacoEditor.ITextModel
 import world.phantasmal.web.externals.monacoEditor.createModel
 import world.phantasmal.web.questEditor.stores.AsmStore
 import world.phantasmal.webui.controllers.Controller
 
 class AsmEditorController(private val store: AsmStore) : Controller() {
-    val enabled: Val<Boolean> = store.editingEnabled
+    val enabled: Cell<Boolean> = store.editingEnabled
-    val readOnly: Val<Boolean> = !enabled or store.textModel.isNull()
+    val readOnly: Cell<Boolean> = !enabled or store.textModel.isNull()
 
-    val textModel: Val<ITextModel> = store.textModel.orElse { EMPTY_MODEL }
+    val textModel: Cell<ITextModel> = store.textModel.orElse { EMPTY_MODEL }
 
     val didUndo: Observable<Unit> = store.didUndo
     val didRedo: Observable<Unit> = store.didRedo
 
-    val inlineStackArgs: Val<Boolean> = store.inlineStackArgs
+    val inlineStackArgs: Cell<Boolean> = store.inlineStackArgs
-    val inlineStackArgsEnabled: Val<Boolean> = store.problems.map { it.isEmpty() }
+    val inlineStackArgsEnabled: Cell<Boolean> = store.problems.map { it.isEmpty() }
-    val inlineStackArgsTooltip: Val<String> =
+    val inlineStackArgsTooltip: Cell<String> =
         inlineStackArgsEnabled.map { enabled ->
             buildString {
                 append("Transform arg_push* opcodes to be inline with the opcode the arguments are given to.")

web/src/main/kotlin/world/phantasmal/web/questEditor/controllers/EntityInfoController.kt

@@ -2,10 +2,10 @@ package world.phantasmal.web.questEditor.controllers
 
 import world.phantasmal.core.math.degToRad
 import world.phantasmal.core.math.radToDeg
-import world.phantasmal.observable.value.Val
+import world.phantasmal.observable.cell.Cell
-import world.phantasmal.observable.value.list.emptyListVal
+import world.phantasmal.observable.cell.cell
-import world.phantasmal.observable.value.value
+import world.phantasmal.observable.cell.list.emptyListCell
-import world.phantasmal.observable.value.zeroIntVal
+import world.phantasmal.observable.cell.zeroIntCell
 import world.phantasmal.web.core.euler
 import world.phantasmal.web.externals.three.Euler
 import world.phantasmal.web.externals.three.Vector3
@@ -21,43 +21,43 @@ class EntityInfoController(
     private val areaStore: AreaStore,
     private val questEditorStore: QuestEditorStore,
 ) : Controller() {
-    val unavailable: Val<Boolean> = questEditorStore.selectedEntity.isNull()
+    val unavailable: Cell<Boolean> = questEditorStore.selectedEntity.isNull()
-    val enabled: Val<Boolean> = questEditorStore.questEditingEnabled
+    val enabled: Cell<Boolean> = questEditorStore.questEditingEnabled
 
-    val type: Val<String> = questEditorStore.selectedEntity.map {
+    val type: Cell<String> = questEditorStore.selectedEntity.map {
         it?.let { if (it is QuestNpcModel) "NPC" else "Object" } ?: ""
     }
 
-    val name: Val<String> = questEditorStore.selectedEntity.map { it?.type?.simpleName ?: "" }
+    val name: Cell<String> = questEditorStore.selectedEntity.map { it?.type?.simpleName ?: "" }
 
-    val sectionId: Val<Int> = questEditorStore.selectedEntity
+    val sectionId: Cell<Int> = questEditorStore.selectedEntity
-        .flatMap { it?.sectionId ?: zeroIntVal() }
+        .flatMap { it?.sectionId ?: zeroIntCell() }
 
-    val waveId: Val<Int> = questEditorStore.selectedEntity
+    val waveId: Cell<Int> = questEditorStore.selectedEntity
         .flatMap { entity ->
             if (entity is QuestNpcModel) {
                 entity.wave.map { it.id }
             } else {
-                zeroIntVal()
+                zeroIntCell()
             }
         }
 
-    val waveHidden: Val<Boolean> = questEditorStore.selectedEntity.map { it !is QuestNpcModel }
+    val waveHidden: Cell<Boolean> = questEditorStore.selectedEntity.map { it !is QuestNpcModel }
 
-    private val pos: Val<Vector3> =
+    private val pos: Cell<Vector3> =
         questEditorStore.selectedEntity.flatMap { it?.position ?: DEFAULT_POSITION }
-    val posX: Val<Double> = pos.map { it.x }
+    val posX: Cell<Double> = pos.map { it.x }
-    val posY: Val<Double> = pos.map { it.y }
+    val posY: Cell<Double> = pos.map { it.y }
-    val posZ: Val<Double> = pos.map { it.z }
+    val posZ: Cell<Double> = pos.map { it.z }
 
-    private val rot: Val<Euler> =
+    private val rot: Cell<Euler> =
         questEditorStore.selectedEntity.flatMap { it?.rotation ?: DEFAULT_ROTATION }
-    val rotX: Val<Double> = rot.map { radToDeg(it.x) }
+    val rotX: Cell<Double> = rot.map { radToDeg(it.x) }
-    val rotY: Val<Double> = rot.map { radToDeg(it.y) }
+    val rotY: Cell<Double> = rot.map { radToDeg(it.y) }
-    val rotZ: Val<Double> = rot.map { radToDeg(it.z) }
+    val rotZ: Cell<Double> = rot.map { radToDeg(it.z) }
 
-    val props: Val<List<QuestEntityPropModel>> =
+    val props: Cell<List<QuestEntityPropModel>> =
-        questEditorStore.selectedEntity.flatMap { it?.properties ?: emptyListVal() }
+        questEditorStore.selectedEntity.flatMap { it?.properties ?: emptyListCell() }
 
     fun focused() {
         questEditorStore.makeMainUndoCurrent()
@@ -178,7 +178,7 @@ class EntityInfoController(
     }
 
     companion object {
-        private val DEFAULT_POSITION = value(Vector3(0.0, 0.0, 0.0))
+        private val DEFAULT_POSITION = cell(Vector3(0.0, 0.0, 0.0))
-        private val DEFAULT_ROTATION = value(euler(0.0, 0.0, 0.0))
+        private val DEFAULT_ROTATION = cell(euler(0.0, 0.0, 0.0))
     }
 }

web/src/main/kotlin/world/phantasmal/web/questEditor/controllers/EntityListController.kt

@@ -1,11 +1,11 @@
 package world.phantasmal.web.questEditor.controllers
 
-import world.phantasmal.lib.fileFormats.quest.EntityType
 import world.phantasmal.lib.Episode
+import world.phantasmal.lib.fileFormats.quest.EntityType
 import world.phantasmal.lib.fileFormats.quest.NpcType
 import world.phantasmal.lib.fileFormats.quest.ObjectType
-import world.phantasmal.observable.value.Val
+import world.phantasmal.observable.cell.Cell
-import world.phantasmal.observable.value.map
+import world.phantasmal.observable.cell.map
 import world.phantasmal.web.questEditor.stores.QuestEditorStore
 import world.phantasmal.webui.controllers.Controller
 
@@ -13,9 +13,9 @@ class EntityListController(store: QuestEditorStore, private val npcs: Boolean) :
     @Suppress("UNCHECKED_CAST")
     private val entityTypes = (if (npcs) NpcType.VALUES else ObjectType.VALUES) as Array<EntityType>
 
-    val enabled: Val<Boolean> = store.questEditingEnabled
+    val enabled: Cell<Boolean> = store.questEditingEnabled
 
-    val entities: Val<List<EntityType>> =
+    val entities: Cell<List<EntityType>> =
         map(store.currentQuest, store.currentArea) { quest, area ->
             val episode = quest?.episode ?: Episode.I
             val areaId = area?.id ?: 0

web/src/main/kotlin/world/phantasmal/web/questEditor/controllers/EventsController.kt

@@ -1,12 +1,12 @@
 package world.phantasmal.web.questEditor.controllers
 
-import world.phantasmal.observable.value.Val
+import world.phantasmal.observable.cell.Cell
-import world.phantasmal.observable.value.and
+import world.phantasmal.observable.cell.and
-import world.phantasmal.observable.value.eq
+import world.phantasmal.observable.cell.eq
-import world.phantasmal.observable.value.list.ListVal
+import world.phantasmal.observable.cell.list.ListCell
-import world.phantasmal.observable.value.list.emptyListVal
+import world.phantasmal.observable.cell.list.emptyListCell
-import world.phantasmal.observable.value.list.flatMapToList
+import world.phantasmal.observable.cell.list.flatMapToList
-import world.phantasmal.observable.value.list.listVal
+import world.phantasmal.observable.cell.list.listCell
 import world.phantasmal.web.questEditor.actions.*
 import world.phantasmal.web.questEditor.models.QuestEventActionModel
 import world.phantasmal.web.questEditor.models.QuestEventModel
@@ -14,20 +14,20 @@ import world.phantasmal.web.questEditor.stores.QuestEditorStore
 import world.phantasmal.webui.controllers.Controller
 
 class EventsController(private val store: QuestEditorStore) : Controller() {
-    val unavailable: Val<Boolean> = store.currentQuest.isNull()
+    val unavailable: Cell<Boolean> = store.currentQuest.isNull()
-    val enabled: Val<Boolean> = store.questEditingEnabled
+    val enabled: Cell<Boolean> = store.questEditingEnabled
-    val removeEventEnabled: Val<Boolean> = enabled and store.selectedEvent.isNotNull()
+    val removeEventEnabled: Cell<Boolean> = enabled and store.selectedEvent.isNotNull()
 
-    val events: ListVal<QuestEventModel> =
+    val events: ListCell<QuestEventModel> =
         flatMapToList(store.currentQuest, store.currentArea) { quest, area ->
             if (quest != null && area != null) {
                 quest.events.filtered { it.areaId == area.id }
             } else {
-                emptyListVal()
+                emptyListCell()
             }
         }
 
-    val eventActionTypes: ListVal<String> = listVal(
+    val eventActionTypes: ListCell<String> = listCell(
         QuestEventActionModel.SpawnNpcs.SHORT_NAME,
         QuestEventActionModel.Door.Unlock.SHORT_NAME,
         QuestEventActionModel.Door.Lock.SHORT_NAME,
@@ -42,7 +42,7 @@ class EventsController(private val store: QuestEditorStore) : Controller() {
         store.makeMainUndoCurrent()
     }
 
-    fun isSelected(event: QuestEventModel): Val<Boolean> =
+    fun isSelected(event: QuestEventModel): Cell<Boolean> =
         store.selectedEvent eq event
 
     fun selectEvent(event: QuestEventModel?) {

web/src/main/kotlin/world/phantasmal/web/questEditor/controllers/NpcCountsController.kt

@@ -1,17 +1,17 @@
 package world.phantasmal.web.questEditor.controllers
 
 import world.phantasmal.lib.fileFormats.quest.NpcType
-import world.phantasmal.observable.value.Val
+import world.phantasmal.observable.cell.Cell
-import world.phantasmal.observable.value.list.emptyListVal
+import world.phantasmal.observable.cell.list.emptyListCell
 import world.phantasmal.web.questEditor.models.QuestNpcModel
 import world.phantasmal.web.questEditor.stores.QuestEditorStore
 import world.phantasmal.webui.controllers.Controller
 
 class NpcCountsController(private val store: QuestEditorStore) : Controller() {
-    val unavailable: Val<Boolean> = store.currentQuest.isNull()
+    val unavailable: Cell<Boolean> = store.currentQuest.isNull()
 
-    val npcCounts: Val<List<NameWithCount>> = store.currentQuest
+    val npcCounts: Cell<List<NameWithCount>> = store.currentQuest
-        .flatMap { it?.npcs ?: emptyListVal() }
+        .flatMap { it?.npcs ?: emptyListCell() }
         .map(::countNpcs)
 
     fun focused() {

web/src/main/kotlin/world/phantasmal/web/questEditor/controllers/QuestEditorToolbarController.kt

@@ -6,7 +6,7 @@ import world.phantasmal.core.*
 import world.phantasmal.lib.Endianness
 import world.phantasmal.lib.Episode
 import world.phantasmal.lib.fileFormats.quest.*
-import world.phantasmal.observable.value.*
+import world.phantasmal.observable.cell.*
 import world.phantasmal.web.core.PwToolType
 import world.phantasmal.web.core.files.cursor
 import world.phantasmal.web.core.files.writeBuffer
@@ -30,22 +30,22 @@ class QuestEditorToolbarController(
     private val areaStore: AreaStore,
     private val questEditorStore: QuestEditorStore,
 ) : Controller() {
-    private val _resultDialogVisible = mutableVal(false)
+    private val _resultDialogVisible = mutableCell(false)
-    private val _result = mutableVal<PwResult<*>?>(null)
+    private val _result = mutableCell<PwResult<*>?>(null)
-    private val saving = mutableVal(false)
+    private val saving = mutableCell(false)
 
     // We mainly disable saving while a save is underway for visual feedback that a save is
     // happening/has happened.
     private val savingEnabled = questEditorStore.currentQuest.isNotNull() and !saving
-    private val _saveAsDialogVisible = mutableVal(false)
+    private val _saveAsDialogVisible = mutableCell(false)
-    private val fileHolder = mutableVal<FileHolder?>(null)
+    private val fileHolder = mutableCell<FileHolder?>(null)
-    private val _filename = mutableVal("")
+    private val _filename = mutableCell("")
-    private val _version = mutableVal(Version.BB)
+    private val _version = mutableCell(Version.BB)
 
     // Result
 
-    val resultDialogVisible: Val<Boolean> = _resultDialogVisible
+    val resultDialogVisible: Cell<Boolean> = _resultDialogVisible
-    val result: Val<PwResult<*>?> = _result
+    val result: Cell<PwResult<*>?> = _result
 
     val supportedFileTypes = listOf(
         FileType(
@@ -56,43 +56,43 @@ class QuestEditorToolbarController(
 
     // Saving
 
-    val saveEnabled: Val<Boolean> =
+    val saveEnabled: Cell<Boolean> =
         savingEnabled and questEditorStore.canSaveChanges and UserAgentFeatures.fileSystemApi
-    val saveTooltip: Val<String> =
+    val saveTooltip: Cell<String> =
         if (UserAgentFeatures.fileSystemApi) {
             questEditorStore.canSaveChanges.map {
                 (if (it) "Save changes" else "No changes to save") + " (Ctrl-S)"
             }
         } else {
-            value("This browser doesn't support saving changes to existing files")
+            cell("This browser doesn't support saving changes to existing files")
         }
-    val saveAsEnabled: Val<Boolean> = savingEnabled
+    val saveAsEnabled: Cell<Boolean> = savingEnabled
-    val saveAsDialogVisible: Val<Boolean> = _saveAsDialogVisible
+    val saveAsDialogVisible: Cell<Boolean> = _saveAsDialogVisible
     val showSaveAsDialogNameField: Boolean = !UserAgentFeatures.fileSystemApi
-    val filename: Val<String> = _filename
+    val filename: Cell<String> = _filename
-    val version: Val<Version> = _version
+    val version: Cell<Version> = _version
 
     // Undo
 
-    val undoTooltip: Val<String> = questEditorStore.firstUndo.map { action ->
+    val undoTooltip: Cell<String> = questEditorStore.firstUndo.map { action ->
         (action?.let { "Undo \"${action.description}\"" } ?: "Nothing to undo") + " (Ctrl-Z)"
     }
 
-    val undoEnabled: Val<Boolean> = questEditorStore.canUndo
+    val undoEnabled: Cell<Boolean> = questEditorStore.canUndo
 
     // Redo
 
-    val redoTooltip: Val<String> = questEditorStore.firstRedo.map { action ->
+    val redoTooltip: Cell<String> = questEditorStore.firstRedo.map { action ->
         (action?.let { "Redo \"${action.description}\"" } ?: "Nothing to redo") + " (Ctrl-Shift-Z)"
     }
 
-    val redoEnabled: Val<Boolean> = questEditorStore.canRedo
+    val redoEnabled: Cell<Boolean> = questEditorStore.canRedo
 
     // Areas
 
     // Ensure the areas list is updated when entities are added or removed (the count in the label
     // should update).
-    val areas: Val<List<AreaAndLabel>> = questEditorStore.currentQuest.flatMap { quest ->
+    val areas: Cell<List<AreaAndLabel>> = questEditorStore.currentQuest.flatMap { quest ->
         quest?.let {
             map(quest.entitiesPerArea, quest.areaVariants) { entitiesPerArea, variants ->
                 areaStore.getAreasForEpisode(quest.episode).map { area ->
@@ -101,18 +101,18 @@ class QuestEditorToolbarController(
                     AreaAndLabel(area, name + (entityCount?.let { " ($it)" } ?: ""))
                 }
             }
-        } ?: value(emptyList())
+        } ?: cell(emptyList())
     }
 
-    val currentArea: Val<AreaAndLabel?> = map(areas, questEditorStore.currentArea) { areas, area ->
+    val currentArea: Cell<AreaAndLabel?> = map(areas, questEditorStore.currentArea) { areas, area ->
         areas.find { it.area == area }
     }
 
-    val areaSelectEnabled: Val<Boolean> = questEditorStore.currentQuest.isNotNull()
+    val areaSelectEnabled: Cell<Boolean> = questEditorStore.currentQuest.isNotNull()
 
     // Settings
 
-    val showCollisionGeometry: Val<Boolean> = questEditorStore.showCollisionGeometry
+    val showCollisionGeometry: Cell<Boolean> = questEditorStore.showCollisionGeometry
 
     init {
         addDisposables(

web/src/main/kotlin/world/phantasmal/web/questEditor/controllers/QuestInfoController.kt

@@ -1,23 +1,23 @@
 package world.phantasmal.web.questEditor.controllers
 
-import world.phantasmal.observable.value.Val
+import world.phantasmal.observable.cell.Cell
-import world.phantasmal.observable.value.emptyStringVal
+import world.phantasmal.observable.cell.cell
-import world.phantasmal.observable.value.value
+import world.phantasmal.observable.cell.emptyStringCell
 import world.phantasmal.web.questEditor.actions.EditPropertyAction
 import world.phantasmal.web.questEditor.stores.QuestEditorStore
 import world.phantasmal.webui.controllers.Controller
 
 class QuestInfoController(private val store: QuestEditorStore) : Controller() {
-    val unavailable: Val<Boolean> = store.currentQuest.isNull()
+    val unavailable: Cell<Boolean> = store.currentQuest.isNull()
-    val enabled: Val<Boolean> = store.questEditingEnabled
+    val enabled: Cell<Boolean> = store.questEditingEnabled
 
-    val episode: Val<String> = store.currentQuest.map { it?.episode?.name ?: "" }
+    val episode: Cell<String> = store.currentQuest.map { it?.episode?.name ?: "" }
-    val id: Val<Int> = store.currentQuest.flatMap { it?.id ?: value(0) }
+    val id: Cell<Int> = store.currentQuest.flatMap { it?.id ?: cell(0) }
-    val name: Val<String> = store.currentQuest.flatMap { it?.name ?: emptyStringVal() }
+    val name: Cell<String> = store.currentQuest.flatMap { it?.name ?: emptyStringCell() }
-    val shortDescription: Val<String> =
+    val shortDescription: Cell<String> =
-        store.currentQuest.flatMap { it?.shortDescription ?: emptyStringVal() }
+        store.currentQuest.flatMap { it?.shortDescription ?: emptyStringCell() }
-    val longDescription: Val<String> =
+    val longDescription: Cell<String> =
-        store.currentQuest.flatMap { it?.longDescription ?: emptyStringVal() }
+        store.currentQuest.flatMap { it?.longDescription ?: emptyStringCell() }
 
     fun focused() {
         store.makeMainUndoCurrent()

web/src/main/kotlin/world/phantasmal/web/questEditor/models/AreaVariantModel.kt

@@ -1,17 +1,17 @@
 package world.phantasmal.web.questEditor.models
 
 import world.phantasmal.core.requireNonNegative
-import world.phantasmal.observable.value.list.ListVal
+import world.phantasmal.observable.cell.list.ListCell
-import world.phantasmal.observable.value.list.mutableListVal
+import world.phantasmal.observable.cell.list.mutableListCell
 
 class AreaVariantModel(val id: Int, val area: AreaModel) {
-    private val _sections = mutableListVal<SectionModel>()
+    private val _sections = mutableListCell<SectionModel>()
 
     // Exception for Seaside Area at Night, variant 1.
     // Phantasmal World 4 and Lost heart breaker use this to have two tower maps.
     val name: String = if (area.id == 16 && id == 1) "West Tower" else area.name
 
-    val sections: ListVal<SectionModel> = _sections
+    val sections: ListCell<SectionModel> = _sections
 
     init {
         requireNonNegative(id, "id")

web/src/main/kotlin/world/phantasmal/web/questEditor/models/QuestEntityModel.kt

@@ -3,10 +3,10 @@ package world.phantasmal.web.questEditor.models
 import world.phantasmal.core.math.floorMod
 import world.phantasmal.lib.fileFormats.quest.EntityType
 import world.phantasmal.lib.fileFormats.quest.QuestEntity
-import world.phantasmal.observable.value.Val
+import world.phantasmal.observable.cell.Cell
-import world.phantasmal.observable.value.list.ListVal
+import world.phantasmal.observable.cell.list.ListCell
-import world.phantasmal.observable.value.list.listVal
+import world.phantasmal.observable.cell.list.listCell
-import world.phantasmal.observable.value.mutableVal
+import world.phantasmal.observable.cell.mutableCell
 import world.phantasmal.web.core.minus
 import world.phantasmal.web.core.rendering.conversion.vec3ToEuler
 import world.phantasmal.web.core.rendering.conversion.vec3ToThree
@@ -24,38 +24,38 @@ abstract class QuestEntityModel<Type : EntityType, Entity : QuestEntity<Type>>(
      */
     val entity: Entity,
 ) {
-    private val _sectionId = mutableVal(entity.sectionId.toInt())
+    private val _sectionId = mutableCell(entity.sectionId.toInt())
-    private val _section = mutableVal<SectionModel?>(null)
+    private val _section = mutableCell<SectionModel?>(null)
-    private val _sectionInitialized = mutableVal(false)
+    private val _sectionInitialized = mutableCell(false)
-    private val _position = mutableVal(vec3ToThree(entity.position))
+    private val _position = mutableCell(vec3ToThree(entity.position))
-    private val _worldPosition = mutableVal(_position.value)
+    private val _worldPosition = mutableCell(_position.value)
-    private val _rotation = mutableVal(vec3ToEuler(entity.rotation))
+    private val _rotation = mutableCell(vec3ToEuler(entity.rotation))
-    private val _worldRotation = mutableVal(_rotation.value)
+    private val _worldRotation = mutableCell(_rotation.value)
 
     val type: Type get() = entity.type
 
     val areaId: Int get() = entity.areaId
 
-    val sectionId: Val<Int> = _sectionId
+    val sectionId: Cell<Int> = _sectionId
 
-    val section: Val<SectionModel?> = _section
+    val section: Cell<SectionModel?> = _section
-    val sectionInitialized: Val<Boolean> = _sectionInitialized
+    val sectionInitialized: Cell<Boolean> = _sectionInitialized
 
     /**
      * Section-relative position
      */
-    val position: Val<Vector3> = _position
+    val position: Cell<Vector3> = _position
 
-    val worldPosition: Val<Vector3> = _worldPosition
+    val worldPosition: Cell<Vector3> = _worldPosition
 
     /**
      * Section-relative rotation
      */
-    val rotation: Val<Euler> = _rotation
+    val rotation: Cell<Euler> = _rotation
 
-    val worldRotation: Val<Euler> = _worldRotation
+    val worldRotation: Cell<Euler> = _worldRotation
 
-    val properties: ListVal<QuestEntityPropModel> = listVal(*Array(type.properties.size) {
+    val properties: ListCell<QuestEntityPropModel> = listCell(*Array(type.properties.size) {
         QuestEntityPropModel(this, type.properties[it])
     })
 

web/src/main/kotlin/world/phantasmal/web/questEditor/models/QuestEntityPropModel.kt

@@ -5,12 +5,12 @@ import world.phantasmal.lib.fileFormats.ninja.radToAngle
 import world.phantasmal.lib.fileFormats.quest.EntityProp
 import world.phantasmal.lib.fileFormats.quest.EntityPropType
 import world.phantasmal.lib.fileFormats.quest.ObjectType
-import world.phantasmal.observable.value.MutableVal
+import world.phantasmal.observable.cell.Cell
-import world.phantasmal.observable.value.Val
+import world.phantasmal.observable.cell.MutableCell
-import world.phantasmal.observable.value.mutableVal
+import world.phantasmal.observable.cell.mutableCell
 
 class QuestEntityPropModel(private val entity: QuestEntityModel<*, *>, prop: EntityProp) {
-    private val _value: MutableVal<Any> = mutableVal(when (prop.type) {
+    private val _value: MutableCell<Any> = mutableCell(when (prop.type) {
         EntityPropType.I32 -> entity.entity.data.getInt(prop.offset)
         EntityPropType.F32 -> entity.entity.data.getFloat(prop.offset)
         EntityPropType.Angle -> angleToRad(entity.entity.data.getInt(prop.offset))
@@ -48,7 +48,7 @@ class QuestEntityPropModel(private val entity: QuestEntityModel<*, *>, prop: Ent
     val name: String = prop.name
     val offset = prop.offset
     val type: EntityPropType = prop.type
-    val value: Val<Any> = _value
+    val value: Cell<Any> = _value
 
     fun setValue(value: Any, propagateToEntity: Boolean = true) {
         when (type) {

web/src/main/kotlin/world/phantasmal/web/questEditor/models/QuestEventActionModel.kt

@@ -1,18 +1,18 @@
 package world.phantasmal.web.questEditor.models
 
-import world.phantasmal.observable.value.Val
+import world.phantasmal.observable.cell.Cell
-import world.phantasmal.observable.value.mutableVal
+import world.phantasmal.observable.cell.mutableCell
 
 sealed class QuestEventActionModel {
     abstract val shortName: String
 
     class SpawnNpcs(sectionId: Int, appearFlag: Int) : QuestEventActionModel() {
-        private val _sectionId = mutableVal(sectionId)
+        private val _sectionId = mutableCell(sectionId)
-        private val _appearFlag = mutableVal(appearFlag)
+        private val _appearFlag = mutableCell(appearFlag)
 
         override val shortName = SHORT_NAME
-        val sectionId: Val<Int> = _sectionId
+        val sectionId: Cell<Int> = _sectionId
-        val appearFlag: Val<Int> = _appearFlag
+        val appearFlag: Cell<Int> = _appearFlag
 
         fun setSectionId(sectionId: Int) {
             _sectionId.value = sectionId
@@ -28,9 +28,9 @@ sealed class QuestEventActionModel {
     }
 
     sealed class Door(doorId: Int) : QuestEventActionModel() {
-        private val _doorId = mutableVal(doorId)
+        private val _doorId = mutableCell(doorId)
 
-        val doorId: Val<Int> = _doorId
+        val doorId: Cell<Int> = _doorId
 
         fun setDoorId(doorId: Int) {
             _doorId.value = doorId
@@ -54,10 +54,10 @@ sealed class QuestEventActionModel {
     }
 
     class TriggerEvent(eventId: Int) : QuestEventActionModel() {
-        private val _eventId = mutableVal(eventId)
+        private val _eventId = mutableCell(eventId)
 
         override val shortName = SHORT_NAME
-        val eventId: Val<Int> = _eventId
+        val eventId: Cell<Int> = _eventId
 
         fun setEventId(eventId: Int) {
             _eventId.value = eventId

web/src/main/kotlin/world/phantasmal/web/questEditor/models/QuestEventModel.kt

@@ -1,10 +1,10 @@
 package world.phantasmal.web.questEditor.models
 
-import world.phantasmal.observable.value.Val
+import world.phantasmal.observable.cell.Cell
-import world.phantasmal.observable.value.list.ListVal
+import world.phantasmal.observable.cell.list.ListCell
-import world.phantasmal.observable.value.list.SimpleListVal
+import world.phantasmal.observable.cell.list.SimpleListCell
-import world.phantasmal.observable.value.map
+import world.phantasmal.observable.cell.map
-import world.phantasmal.observable.value.mutableVal
+import world.phantasmal.observable.cell.mutableCell
 
 class QuestEventModel(
     id: Int,
@@ -15,19 +15,19 @@ class QuestEventModel(
     val unknown: Int,
     actions: MutableList<QuestEventActionModel>,
 ) {
-    private val _id = mutableVal(id)
+    private val _id = mutableCell(id)
-    private val _sectionId = mutableVal(sectionId)
+    private val _sectionId = mutableCell(sectionId)
-    private val _waveId = mutableVal(waveId)
+    private val _waveId = mutableCell(waveId)
-    private val _delay = mutableVal(delay)
+    private val _delay = mutableCell(delay)
-    private val _actions = SimpleListVal(actions)
+    private val _actions = SimpleListCell(actions)
 
-    val id: Val<Int> = _id
+    val id: Cell<Int> = _id
-    val sectionId: Val<Int> = _sectionId
+    val sectionId: Cell<Int> = _sectionId
-    val wave: Val<WaveModel> = map(_waveId, _sectionId) { id, sectionId ->
+    val wave: Cell<WaveModel> = map(_waveId, _sectionId) { id, sectionId ->
         WaveModel(id, areaId, sectionId)
     }
-    val delay: Val<Int> = _delay
+    val delay: Cell<Int> = _delay
-    val actions: ListVal<QuestEventActionModel> = _actions
+    val actions: ListCell<QuestEventActionModel> = _actions
 
     fun setId(id: Int) {
         _id.value = id

web/src/main/kotlin/world/phantasmal/web/questEditor/models/QuestModel.kt

@@ -3,13 +3,13 @@ package world.phantasmal.web.questEditor.models
 import world.phantasmal.lib.Episode
 import world.phantasmal.lib.asm.BytecodeIr
 import world.phantasmal.lib.fileFormats.quest.DatUnknown
-import world.phantasmal.observable.value.Val
+import world.phantasmal.observable.cell.Cell
-import world.phantasmal.observable.value.list.ListVal
+import world.phantasmal.observable.cell.list.ListCell
-import world.phantasmal.observable.value.list.SimpleListVal
+import world.phantasmal.observable.cell.list.SimpleListCell
-import world.phantasmal.observable.value.list.flatMapToList
+import world.phantasmal.observable.cell.list.flatMapToList
-import world.phantasmal.observable.value.list.listVal
+import world.phantasmal.observable.cell.list.listCell
-import world.phantasmal.observable.value.map
+import world.phantasmal.observable.cell.map
-import world.phantasmal.observable.value.mutableVal
+import world.phantasmal.observable.cell.mutableCell
 
 class QuestModel(
     id: Int,
@@ -30,41 +30,41 @@ class QuestModel(
     val shopItems: UIntArray,
     getVariant: (Episode, areaId: Int, variantId: Int) -> AreaVariantModel?,
 ) {
-    private val _id = mutableVal(0)
+    private val _id = mutableCell(0)
-    private val _language = mutableVal(0)
+    private val _language = mutableCell(0)
-    private val _name = mutableVal("")
+    private val _name = mutableCell("")
-    private val _shortDescription = mutableVal("")
+    private val _shortDescription = mutableCell("")
-    private val _longDescription = mutableVal("")
+    private val _longDescription = mutableCell("")
-    private val _mapDesignations = mutableVal(mapDesignations)
+    private val _mapDesignations = mutableCell(mapDesignations)
-    private val _npcs = SimpleListVal(npcs) { arrayOf(it.sectionInitialized, it.wave) }
+    private val _npcs = SimpleListCell(npcs) { arrayOf(it.sectionInitialized, it.wave) }
-    private val _objects = SimpleListVal(objects) { arrayOf(it.sectionInitialized) }
+    private val _objects = SimpleListCell(objects) { arrayOf(it.sectionInitialized) }
-    private val _events = SimpleListVal(events)
+    private val _events = SimpleListCell(events)
 
-    val id: Val<Int> = _id
+    val id: Cell<Int> = _id
-    val language: Val<Int> = _language
+    val language: Cell<Int> = _language
-    val name: Val<String> = _name
+    val name: Cell<String> = _name
-    val shortDescription: Val<String> = _shortDescription
+    val shortDescription: Cell<String> = _shortDescription
-    val longDescription: Val<String> = _longDescription
+    val longDescription: Cell<String> = _longDescription
 
     /**
      * Map of area IDs to area variant IDs. One designation per area.
      */
-    val mapDesignations: Val<Map<Int, Int>> = _mapDesignations
+    val mapDesignations: Cell<Map<Int, Int>> = _mapDesignations
 
     /**
      * Map of area IDs to entity counts.
      */
-    val entitiesPerArea: Val<Map<Int, Int>>
+    val entitiesPerArea: Cell<Map<Int, Int>>
 
     /**
      * One variant per area.
      */
-    val areaVariants: ListVal<AreaVariantModel>
+    val areaVariants: ListCell<AreaVariantModel>
 
-    val npcs: ListVal<QuestNpcModel> = _npcs
+    val npcs: ListCell<QuestNpcModel> = _npcs
-    val objects: ListVal<QuestObjectModel> = _objects
+    val objects: ListCell<QuestObjectModel> = _objects
 
-    val events: ListVal<QuestEventModel> = _events
+    val events: ListCell<QuestEventModel> = _events
 
     var bytecodeIr: BytecodeIr = bytecodeIr
         private set
@@ -106,7 +106,7 @@ class QuestModel(
                     }
                 }
 
-                listVal(*variants.values.toTypedArray())
+                listCell(*variants.values.toTypedArray())
             }
     }
 

web/src/main/kotlin/world/phantasmal/web/questEditor/models/QuestNpcModel.kt

@@ -2,14 +2,14 @@ package world.phantasmal.web.questEditor.models
 
 import world.phantasmal.lib.fileFormats.quest.NpcType
 import world.phantasmal.lib.fileFormats.quest.QuestNpc
-import world.phantasmal.observable.value.Val
+import world.phantasmal.observable.cell.Cell
-import world.phantasmal.observable.value.map
+import world.phantasmal.observable.cell.map
-import world.phantasmal.observable.value.mutableVal
+import world.phantasmal.observable.cell.mutableCell
 
 class QuestNpcModel(npc: QuestNpc, waveId: Int) : QuestEntityModel<NpcType, QuestNpc>(npc) {
-    private val _waveId = mutableVal(waveId)
+    private val _waveId = mutableCell(waveId)
 
-    val wave: Val<WaveModel> = map(_waveId, sectionId) { id, sectionId ->
+    val wave: Cell<WaveModel> = map(_waveId, sectionId) { id, sectionId ->
         WaveModel(id, areaId, sectionId)
     }
 

web/src/main/kotlin/world/phantasmal/web/questEditor/models/QuestObjectModel.kt

@@ -2,13 +2,13 @@ package world.phantasmal.web.questEditor.models
 
 import world.phantasmal.lib.fileFormats.quest.ObjectType
 import world.phantasmal.lib.fileFormats.quest.QuestObject
-import world.phantasmal.observable.value.Val
+import world.phantasmal.observable.cell.Cell
-import world.phantasmal.observable.value.mutableVal
+import world.phantasmal.observable.cell.mutableCell
 
 class QuestObjectModel(obj: QuestObject) : QuestEntityModel<ObjectType, QuestObject>(obj) {
-    private val _model = mutableVal(obj.model)
+    private val _model = mutableCell(obj.model)
 
-    val model: Val<Int?> = _model
+    val model: Cell<Int?> = _model
 
     fun setModel(model: Int, propagateToProps: Boolean = true) {
         _model.value = model

web/src/main/kotlin/world/phantasmal/web/questEditor/rendering/QuestEditorMeshManager.kt

@@ -1,6 +1,6 @@
 package world.phantasmal.web.questEditor.rendering
 
-import world.phantasmal.observable.value.list.emptyListVal
+import world.phantasmal.observable.cell.list.emptyListCell
 import world.phantasmal.web.questEditor.loading.AreaAssetLoader
 import world.phantasmal.web.questEditor.loading.EntityAssetLoader
 import world.phantasmal.web.questEditor.stores.QuestEditorStore
@@ -32,7 +32,7 @@ class QuestEditorMeshManager(
                                 (wave == null || it.wave.value == wave)
                     }
                 } else {
-                    emptyListVal()
+                    emptyListCell()
                 }
             )
         }
@@ -47,7 +47,7 @@ class QuestEditorMeshManager(
                         it.sectionInitialized.value && it.areaId == area.id
                     }
                 } else {
-                    emptyListVal()
+                    emptyListCell()
                 }
             )
         }