diff --git a/packages/@react-stately/autocomplete/src/useAutocompleteState.ts b/packages/@react-stately/autocomplete/src/useAutocompleteState.ts
index e9b4ce28d53..fb67ac9deb2 100644
--- a/packages/@react-stately/autocomplete/src/useAutocompleteState.ts
+++ b/packages/@react-stately/autocomplete/src/useAutocompleteState.ts
@@ -17,11 +17,11 @@ export interface AutocompleteState {
   /** The current value of the autocomplete input. */
   inputValue: string,
   /** Sets the value of the autocomplete input. */
-  setInputValue(value: string): void,
+  setInputValue: (value: string) => void,
   /** The id of the current aria-activedescendant of the autocomplete input. */
   focusedNodeId: string | null,
   /** Sets the id of the current aria-activedescendant of the autocomplete input. */
-  setFocusedNodeId(value: string | null): void
+  setFocusedNodeId: (value: string | null) => void
 }
 
 export interface AutocompleteProps {
diff --git a/packages/@react-stately/calendar/src/types.ts b/packages/@react-stately/calendar/src/types.ts
index 4fbf3c3fe60..2cedf10f196 100644
--- a/packages/@react-stately/calendar/src/types.ts
+++ b/packages/@react-stately/calendar/src/types.ts
@@ -37,23 +37,23 @@ interface CalendarStateBase {
   /** The currently focused date. */
   readonly focusedDate: CalendarDate,
   /** Sets the focused date. */
-  setFocusedDate(value: CalendarDate): void,
+  setFocusedDate: (value: CalendarDate) => void,
   /** Moves focus to the next calendar date. */
-  focusNextDay(): void,
+  focusNextDay: () => void,
   /** Moves focus to the previous calendar date. */
-  focusPreviousDay(): void,
+  focusPreviousDay: () => void,
   /** Moves focus to the next row of dates, e.g. the next week. */
-  focusNextRow(): void,
+  focusNextRow: () => void,
   /** Moves focus to the previous row of dates, e.g. the previous work. */
-  focusPreviousRow(): void,
+  focusPreviousRow: () => void,
   /** Moves focus to the next page of dates, e.g. the next month if one month is visible. */
-  focusNextPage(): void,
+  focusNextPage: () => void,
   /** Moves focus to the previous page of dates, e.g. the previous month if one month is visible. */
-  focusPreviousPage(): void,
+  focusPreviousPage: () => void,
   /** Moves focus to the start of the current section of dates, e.g. the start of the current month. */
-  focusSectionStart(): void,
+  focusSectionStart: () => void,
   /** Moves focus to the end of the current section of dates, e.g. the end of the current month month. */
-  focusSectionEnd(): void,
+  focusSectionEnd: () => void,
   /**
    * Moves focus to the next section of dates based on what is currently displayed.
    * By default, focus is moved by one of the currently displayed unit. For example, if
@@ -61,7 +61,7 @@ interface CalendarStateBase {
    * If the `larger` option is `true`, the focus is moved by the next larger unit than
    * the one displayed. For example, if months are displayed, then focus moves to the next year.
    */
-  focusNextSection(larger?: boolean): void,
+  focusNextSection: (larger?: boolean) => void,
   /**
    * Moves focus to the previous section of dates based on what is currently displayed.
    * By default, focus is moved by one of the currently displayed unit. For example, if
@@ -69,58 +69,58 @@ interface CalendarStateBase {
    * If the `larger` option is `true`, the focus is moved by the next larger unit than
    * the one displayed. For example, if months are displayed, then focus moves to the previous year.
    */
-  focusPreviousSection(larger?: boolean): void,
+  focusPreviousSection: (larger?: boolean) => void,
   /** Selects the currently focused date. */
-  selectFocusedDate(): void,
+  selectFocusedDate: () => void,
   /** Selects the given date. */
-  selectDate(date: CalendarDate): void,
+  selectDate: (date: CalendarDate) => void,
   /** Whether focus is currently within the calendar. */
   readonly isFocused: boolean,
   /** Sets whether focus is currently within the calendar. */
-  setFocused(value: boolean): void,
+  setFocused: (value: boolean) => void,
   /** Returns whether the given date is invalid according to the `minValue` and `maxValue` props. */
-  isInvalid(date: CalendarDate): boolean,
+  isInvalid: (date: CalendarDate) => boolean,
   /** Returns whether the given date is currently selected. */
-  isSelected(date: CalendarDate): boolean,
+  isSelected: (date: CalendarDate) => boolean,
   /** Returns whether the given date is currently focused. */
-  isCellFocused(date: CalendarDate): boolean,
+  isCellFocused: (date: CalendarDate) => boolean,
   /** Returns whether the given date is disabled according to the `minValue, `maxValue`, and `isDisabled` props. */
-  isCellDisabled(date: CalendarDate): boolean,
+  isCellDisabled: (date: CalendarDate) => boolean,
   /** Returns whether the given date is unavailable according to the `isDateUnavailable` prop. */
-  isCellUnavailable(date: CalendarDate): boolean,
+  isCellUnavailable: (date: CalendarDate) => boolean,
   /** Returns whether the previous visible date range is allowed to be selected according to the `minValue` prop. */
-  isPreviousVisibleRangeInvalid(): boolean,
+  isPreviousVisibleRangeInvalid: () => boolean,
   /** Returns whether the next visible date range is allowed to be selected according to the `maxValue` prop. */
-  isNextVisibleRangeInvalid(): boolean,
+  isNextVisibleRangeInvalid: () => boolean,
   /**
    * Returns an array of dates in the week index counted from the provided start date, or the first visible date if not given.
    * The returned array always has 7 elements, but may include null if the date does not exist according to the calendar system.
    */
-  getDatesInWeek(weekIndex: number, startDate?: CalendarDate): Array<CalendarDate | null>
+  getDatesInWeek: (weekIndex: number, startDate?: CalendarDate) => Array<CalendarDate | null>
 }
 
 export interface CalendarState extends CalendarStateBase {
   /** The currently selected date. */
   readonly value: CalendarDate | null,
   /** Sets the currently selected date. */
-  setValue(value: CalendarDate | null): void
+  setValue: (value: CalendarDate | null) => void
 }
 
 export interface RangeCalendarState extends CalendarStateBase {
   /** The currently selected date range. */
   readonly value: RangeValue<DateValue> | null,
   /** Sets the currently selected date range. */
-  setValue(value: RangeValue<DateValue> | null): void,
+  setValue: (value: RangeValue<DateValue> | null) => void,
   /** Highlights the given date during selection, e.g. by hovering or dragging. */
-  highlightDate(date: CalendarDate): void,
+  highlightDate: (date: CalendarDate) => void,
   /** The current anchor date that the user clicked on to begin range selection. */
   readonly anchorDate: CalendarDate | null,
   /** Sets the anchor date that the user clicked on to begin range selection. */
-  setAnchorDate(date: CalendarDate | null): void,
+  setAnchorDate: (date: CalendarDate | null) => void,
   /** The currently highlighted date range. */
   readonly highlightedRange: RangeValue<CalendarDate> | null,
   /** Whether the user is currently dragging over the calendar. */
   readonly isDragging: boolean,
   /** Sets whether the user is dragging over the calendar. */
-  setDragging(isDragging: boolean): void
+  setDragging: (isDragging: boolean) => void
 }
diff --git a/packages/@react-stately/checkbox/src/useCheckboxGroupState.ts b/packages/@react-stately/checkbox/src/useCheckboxGroupState.ts
index b1f1d2db9fa..45c8b01653e 100644
--- a/packages/@react-stately/checkbox/src/useCheckboxGroupState.ts
+++ b/packages/@react-stately/checkbox/src/useCheckboxGroupState.ts
@@ -44,22 +44,22 @@ export interface CheckboxGroupState extends FormValidationState {
   readonly isRequired: boolean,
 
   /** Returns whether the given value is selected. */
-  isSelected(value: string): boolean,
+  isSelected: (value: string) => boolean,
 
   /** Sets the selected values. */
-  setValue(value: string[]): void,
+  setValue: (value: string[]) => void,
 
   /** Adds a value to the set of selected values. */
-  addValue(value: string): void,
+  addValue: (value: string) => void,
 
   /** Removes a value from the set of selected values. */
-  removeValue(value: string): void,
+  removeValue: (value: string) => void,
 
   /** Toggles a value in the set of selected values. */
-  toggleValue(value: string): void,
+  toggleValue: (value: string) => void,
 
   /** Sets whether one of the checkboxes is invalid. */
-  setInvalid(value: string, validation: ValidationResult): void
+  setInvalid: (value: string, validation: ValidationResult) => void
 }
 
 /**
diff --git a/packages/@react-stately/color/src/useColorAreaState.ts b/packages/@react-stately/color/src/useColorAreaState.ts
index 07884c3a379..b6745622d48 100644
--- a/packages/@react-stately/color/src/useColorAreaState.ts
+++ b/packages/@react-stately/color/src/useColorAreaState.ts
@@ -21,37 +21,37 @@ export interface ColorAreaState {
   /** The default value of the color area. */
   readonly defaultValue: Color,
   /** Sets the current color value. If a string is passed, it will be parsed to a Color. */
-  setValue(value: string | Color): void,
+  setValue: (value: string | Color) => void,
 
   /** The current value of the horizontal axis channel displayed by the color area. */
   xValue: number,
   /** Sets the value for the horizontal axis channel displayed by the color area, and triggers `onChange`. */
-  setXValue(value: number): void,
+  setXValue: (value: number) => void,
 
   /** The current value of the vertical axis channel displayed by the color area. */
   yValue: number,
   /** Sets the value for the vertical axis channel displayed by the color area, and triggers `onChange`. */
-  setYValue(value: number): void,
+  setYValue: (value: number) => void,
 
   /** Sets the x and y channels of the current color value based on a percentage of the width and height of the color area, and triggers `onChange`. */
-  setColorFromPoint(x: number, y: number): void,
+  setColorFromPoint: (x: number, y: number) => void,
   /** Returns the coordinates of the thumb relative to the upper left corner of the color area as a percentage. */
-  getThumbPosition(): {x: number, y: number},
+  getThumbPosition: () => {x: number, y: number},
 
   /** Increments the value of the horizontal axis channel by the channel step or page amount. */
-  incrementX(stepSize?: number): void,
+  incrementX: (stepSize?: number) => void,
   /** Decrements the value of the horizontal axis channel by the channel step or page amount. */
-  decrementX(stepSize?: number): void,
+  decrementX: (stepSize?: number) => void,
 
   /** Increments the value of the vertical axis channel by the channel step or page amount. */
-  incrementY(stepSize?: number): void,
+  incrementY: (stepSize?: number) => void,
   /** Decrements the value of the vertical axis channel by the channel step or page amount. */
-  decrementY(stepSize?: number): void,
+  decrementY: (stepSize?: number) => void,
 
   /** Whether the color area is currently being dragged. */
   readonly isDragging: boolean,
   /** Sets whether the color area is being dragged. */
-  setDragging(value: boolean): void,
+  setDragging: (value: boolean) => void,
 
   /** Returns the xChannel, yChannel and zChannel names based on the color value. */
   channels: {xChannel: ColorChannel, yChannel: ColorChannel, zChannel: ColorChannel},
@@ -65,7 +65,7 @@ export interface ColorAreaState {
   yChannelPageStep: number,
 
   /** Returns the color that should be displayed in the color area thumb instead of `value`. */
-  getDisplayColor(): Color
+  getDisplayColor: () => Color
 }
 
 const DEFAULT_COLOR = parseColor('#ffffff');
diff --git a/packages/@react-stately/color/src/useColorChannelFieldState.ts b/packages/@react-stately/color/src/useColorChannelFieldState.ts
index 05d10d5dd59..c7fa5fb400e 100644
--- a/packages/@react-stately/color/src/useColorChannelFieldState.ts
+++ b/packages/@react-stately/color/src/useColorChannelFieldState.ts
@@ -19,7 +19,7 @@ export interface ColorChannelFieldState extends NumberFieldState {
   /** The default value of the field. */
   defaultColorValue: Color | null,
   /** Sets the color value of the field. */
-  setColorValue(value: Color | null): void
+  setColorValue: (value: Color | null) => void
 }
 
 /**
diff --git a/packages/@react-stately/color/src/useColorFieldState.ts b/packages/@react-stately/color/src/useColorFieldState.ts
index 94371a9bf1b..2a24c2a6681 100644
--- a/packages/@react-stately/color/src/useColorFieldState.ts
+++ b/packages/@react-stately/color/src/useColorFieldState.ts
@@ -31,28 +31,28 @@ export interface ColorFieldState extends FormValidationState {
   /** The default value of the color field. */
   readonly defaultColorValue: Color | null,
   /** Sets the color value of the field. */
-  setColorValue(value: Color | null): void,
+  setColorValue: (value: Color | null) => void,
   /** Sets the current text value of the input. */
-  setInputValue(value: string): void,
+  setInputValue: (value: string) => void,
   /**
    * Updates the input value based on the currently parsed color value.
    * Typically this is called when the field is blurred.
    */
-  commit(): void,
+  commit: () => void,
   /** Increments the current input value to the next step boundary, and fires `onChange`. */
-  increment(): void,
+  increment: () => void,
   /** Decrements the current input value to the next step boundary, and fires `onChange`. */
-  decrement(): void,
+  decrement: () => void,
   /** Sets the current value to the maximum color value, and fires `onChange`. */
-  incrementToMax(): void,
+  incrementToMax: () => void,
   /** Sets the current value to the minimum color value, and fires `onChange`. */
-  decrementToMin(): void,
+  decrementToMin: () => void,
   /**
    * Validates a user input string.
    * Values can be partially entered, and may be valid even if they cannot currently be parsed to a color.
    * Can be used to implement validation as a user types.
    */
-  validate(value: string): boolean
+  validate: (value: string) => boolean
 }
 
 const MIN_COLOR = parseColor('#000000');
diff --git a/packages/@react-stately/color/src/useColorPickerState.ts b/packages/@react-stately/color/src/useColorPickerState.ts
index 6592a513c35..7a15e8e8063 100644
--- a/packages/@react-stately/color/src/useColorPickerState.ts
+++ b/packages/@react-stately/color/src/useColorPickerState.ts
@@ -10,7 +10,7 @@ export interface ColorPickerState {
   /** The current color value of the color picker. */
   color: Color,
   /** Sets the current color value of the color picker. */
-  setColor(color: Color | null): void
+  setColor: (color: Color | null) => void
 }
 
 export function useColorPickerState(props: ColorPickerProps): ColorPickerState {
diff --git a/packages/@react-stately/color/src/useColorSliderState.ts b/packages/@react-stately/color/src/useColorSliderState.ts
index 5c9bbf8feb3..ef8e964e932 100644
--- a/packages/@react-stately/color/src/useColorSliderState.ts
+++ b/packages/@react-stately/color/src/useColorSliderState.ts
@@ -20,9 +20,9 @@ export interface ColorSliderState extends SliderState {
   /** The current color value represented by the color slider. */
   readonly value: Color,
   /** Sets the current color value. If a string is passed, it will be parsed to a Color. */
-  setValue(value: string | Color): void,
+  setValue: (value: string | Color) => void,
   /** Returns the color that should be displayed in the slider instead of `value` or the optional parameter. */
-  getDisplayColor(): Color,
+  getDisplayColor: () => Color,
   /** Whether the color slider is currently being dragged. */
   readonly isDragging: boolean
 }
diff --git a/packages/@react-stately/color/src/useColorWheelState.ts b/packages/@react-stately/color/src/useColorWheelState.ts
index 9d9f34bc69e..8aa870aac34 100644
--- a/packages/@react-stately/color/src/useColorWheelState.ts
+++ b/packages/@react-stately/color/src/useColorWheelState.ts
@@ -21,29 +21,29 @@ export interface ColorWheelState {
   /** The default color value. */
   readonly defaultValue: Color,
   /** Sets the color value represented by the color wheel, and triggers `onChange`. */
-  setValue(value: string | Color): void,
+  setValue: (value: string | Color) => void,
 
   /** The current value of the hue channel displayed by the color wheel. */
   readonly hue: number,
   /** Sets the hue channel of the current color value and triggers `onChange`. */
-  setHue(value: number): void,
+  setHue: (value: number) => void,
 
   /** Sets the hue channel of the current color value based on the given coordinates and radius of the color wheel, and triggers `onChange`. */
-  setHueFromPoint(x: number, y: number, radius: number): void,
+  setHueFromPoint: (x: number, y: number, radius: number) => void,
   /** Returns the coordinates of the thumb relative to the center point of the color wheel. */
-  getThumbPosition(radius: number): {x: number, y: number},
+  getThumbPosition: (radius: number) => {x: number, y: number},
 
   /** Increments the hue by the given amount (defaults to 1). */
-  increment(stepSize?: number): void,
+  increment: (stepSize?: number) => void,
   /** Decrements the hue by the given amount (defaults to 1). */
-  decrement(stepSize?: number): void,
+  decrement: (stepSize?: number) => void,
 
   /** Whether the color wheel is currently being dragged. */
   readonly isDragging: boolean,
   /** Sets whether the color wheel is being dragged. */
-  setDragging(value: boolean): void,
+  setDragging: (value: boolean) => void,
   /** Returns the color that should be displayed in the color wheel instead of `value`. */
-  getDisplayColor(): Color,
+  getDisplayColor: () => Color,
   /** The step value of the hue channel, used when incrementing and decrementing. */
   step: number,
   /** The page step value of the hue channel, used when incrementing and decrementing. */
diff --git a/packages/@react-stately/combobox/src/useComboBoxState.ts b/packages/@react-stately/combobox/src/useComboBoxState.ts
index 8278ca9a05b..67ffc9bfbe2 100644
--- a/packages/@react-stately/combobox/src/useComboBoxState.ts
+++ b/packages/@react-stately/combobox/src/useComboBoxState.ts
@@ -26,17 +26,17 @@ export interface ComboBoxState<T> extends SelectState<T>, FormValidationState{
   /** The default value of the combo box input. */
   defaultInputValue: string,
   /** Sets the value of the combo box input. */
-  setInputValue(value: string): void,
+  setInputValue: (value: string) => void,
   /** Selects the currently focused item and updates the input value. */
-  commit(): void,
+  commit: () => void,
   /** Controls which item will be auto focused when the menu opens. */
   readonly focusStrategy: FocusStrategy | null,
   /** Opens the menu. */
-  open(focusStrategy?: FocusStrategy | null, trigger?: MenuTriggerAction): void,
+  open: (focusStrategy?: FocusStrategy | null, trigger?: MenuTriggerAction) => void,
   /** Toggles the menu. */
-  toggle(focusStrategy?: FocusStrategy | null, trigger?: MenuTriggerAction): void,
+  toggle: (focusStrategy?: FocusStrategy | null, trigger?: MenuTriggerAction) => void,
   /** Resets the input value to the previously selected item's text if any and closes the menu.  */
-  revert(): void
+  revert: () => void
 }
 
 type FilterFn = (textValue: string, inputValue: string) => boolean;
diff --git a/packages/@react-stately/data/src/useAsyncList.ts b/packages/@react-stately/data/src/useAsyncList.ts
index 5bf913cc9a6..28d9717e660 100644
--- a/packages/@react-stately/data/src/useAsyncList.ts
+++ b/packages/@react-stately/data/src/useAsyncList.ts
@@ -102,11 +102,11 @@ export interface AsyncListData<T> extends ListData<T> {
   sortDescriptor?: SortDescriptor,
 
   /** Reloads the data in the list. */
-  reload(): void,
+  reload: () => void,
   /** Loads the next page of data in the list. */
-  loadMore(): void,
+  loadMore: () => void,
   /** Triggers sorting for the list. */
-  sort(descriptor: SortDescriptor): void,
+  sort: (descriptor: SortDescriptor) => void,
   /** The current loading state for the list. */
   loadingState: LoadingState
 }
diff --git a/packages/@react-stately/data/src/useListData.ts b/packages/@react-stately/data/src/useListData.ts
index 1e8b6a840e5..5102306d7f5 100644
--- a/packages/@react-stately/data/src/useListData.ts
+++ b/packages/@react-stately/data/src/useListData.ts
@@ -34,92 +34,92 @@ export interface ListData<T> {
   selectedKeys: Selection,
 
   /** Sets the selected keys. */
-  setSelectedKeys(keys: Selection): void,
+  setSelectedKeys: (keys: Selection) => void,
 
   /** The current filter text. */
   filterText: string,
 
   /** Sets the filter text. */
-  setFilterText(filterText: string): void,
+  setFilterText: (filterText: string) => void,
 
   /**
    * Gets an item from the list by key.
    * @param key - The key of the item to retrieve.
    */
-  getItem(key: Key): T | undefined,
+  getItem: (key: Key) => T | undefined,
 
   /**
    * Inserts items into the list at the given index.
    * @param index - The index to insert into.
    * @param values - The values to insert.
    */
-  insert(index: number, ...values: T[]): void,
+  insert: (index: number, ...values: T[]) => void,
 
   /**
    * Inserts items into the list before the item at the given key.
    * @param key - The key of the item to insert before.
    * @param values - The values to insert.
    */
-  insertBefore(key: Key, ...values: T[]): void,
+  insertBefore: (key: Key, ...values: T[]) => void,
 
   /**
    * Inserts items into the list after the item at the given key.
    * @param key - The key of the item to insert after.
    * @param values - The values to insert.
    */
-  insertAfter(key: Key, ...values: T[]): void,
+  insertAfter: (key: Key, ...values: T[]) => void,
 
   /**
    * Appends items to the list.
    * @param values - The values to insert.
    */
-  append(...values: T[]): void,
+  append: (...values: T[]) => void,
 
   /**
    * Prepends items to the list.
    * @param value - The value to insert.
    */
-  prepend(...values: T[]): void,
+  prepend: (...values: T[]) => void,
 
   /**
    * Removes items from the list by their keys.
    * @param keys - The keys of the item to remove.
    */
-  remove(...keys: Key[]): void,
+  remove: (...keys: Key[]) => void,
 
   /**
    * Removes all items from the list that are currently
    * in the set of selected items.
    */
-  removeSelectedItems(): void,
+  removeSelectedItems: () => void,
 
   /**
    * Moves an item within the list.
    * @param key - The key of the item to move.
    * @param toIndex - The index to move the item to.
    */
-  move(key: Key, toIndex: number): void,
+  move: (key: Key, toIndex: number) => void,
 
   /**
    * Moves one or more items before a given key.
    * @param key - The key of the item to move the items before.
    * @param keys - The keys of the items to move.
    */
-  moveBefore(key: Key, keys: Iterable<Key>): void,
+  moveBefore: (key: Key, keys: Iterable<Key>) => void,
 
   /**
    * Moves one or more items after a given key.
    * @param key - The key of the item to move the items after.
    * @param keys - The keys of the items to move.
    */
-  moveAfter(key: Key, keys: Iterable<Key>): void,
+  moveAfter: (key: Key, keys: Iterable<Key>) => void,
 
   /**
    * Updates an item in the list.
    * @param key - The key of the item to update.
    * @param newValue - The new value for the item.
    */
-  update(key: Key, newValue: T): void
+  update: (key: Key, newValue: T) => void
 }
 
 export interface ListState<T> {
diff --git a/packages/@react-stately/data/src/useTreeData.ts b/packages/@react-stately/data/src/useTreeData.ts
index 5baf6d8f3f9..960ede55bf1 100644
--- a/packages/@react-stately/data/src/useTreeData.ts
+++ b/packages/@react-stately/data/src/useTreeData.ts
@@ -43,13 +43,13 @@ export interface TreeData<T extends object> {
   selectedKeys: Set<Key>,
 
   /** Sets the selected keys. */
-  setSelectedKeys(keys: Set<Key>): void,
+  setSelectedKeys: (keys: Set<Key>) => void,
 
   /**
    * Gets a node from the tree by key.
    * @param key - The key of the item to retrieve.
    */
-  getItem(key: Key): TreeNode<T> | undefined,
+  getItem: (key: Key) => TreeNode<T> | undefined,
 
   /**
    * Inserts an item into a parent node as a child.
@@ -57,47 +57,47 @@ export interface TreeData<T extends object> {
    * @param index - The index within the parent to insert into.
    * @param value - The value to insert.
    */
-  insert(parentKey: Key | null, index: number, ...values: T[]): void,
+  insert: (parentKey: Key | null, index: number, ...values: T[]) => void,
 
   /**
    * Inserts items into the list before the item at the given key.
    * @param key - The key of the item to insert before.
    * @param values - The values to insert.
    */
-  insertBefore(key: Key, ...values: T[]): void,
+  insertBefore: (key: Key, ...values: T[]) => void,
 
   /**
    * Inserts items into the list after the item at the given key.
    * @param key - The key of the item to insert after.
    * @param values - The values to insert.
    */
-  insertAfter(key: Key, ...values: T[]): void,
+  insertAfter: (key: Key, ...values: T[]) => void,
 
   /**
    * Appends an item into a parent node as a child.
    * @param parentKey - The key of the parent item to insert into. `null` for the root.
    * @param value - The value to insert.
    */
-  append(parentKey: Key | null, ...values: T[]): void,
+  append: (parentKey: Key | null, ...values: T[]) => void,
 
   /**
    * Prepends an item into a parent node as a child.
    * @param parentKey - The key of the parent item to insert into. `null` for the root.
    * @param value - The value to insert.
    */
-  prepend(parentKey: Key | null, ...value: T[]): void,
+  prepend: (parentKey: Key | null, ...value: T[]) => void,
 
   /**
    * Removes an item from the tree by its key.
    * @param key - The key of the item to remove.
    */
-  remove(...keys: Key[]): void,
+  remove: (...keys: Key[]) => void,
 
   /**
    * Removes all items from the tree that are currently
    * in the set of selected items.
    */
-  removeSelectedItems(): void,
+  removeSelectedItems: () => void,
 
   /**
    * Moves an item within the tree.
@@ -105,28 +105,28 @@ export interface TreeData<T extends object> {
    * @param toParentKey - The key of the new parent to insert into. `null` for the root.
    * @param index - The index within the new parent to insert at.
    */
-  move(key: Key, toParentKey: Key | null, index: number): void,
+  move: (key: Key, toParentKey: Key | null, index: number) => void,
 
   /**
    * Moves one or more items before a given key.
    * @param key - The key of the item to move the items before.
    * @param keys - The keys of the items to move.
    */
-  moveBefore(key: Key, keys: Iterable<Key>): void,
+  moveBefore: (key: Key, keys: Iterable<Key>) => void,
 
   /**
    * Moves one or more items after a given key.
    * @param key - The key of the item to move the items after.
    * @param keys - The keys of the items to move.
    */
-  moveAfter(key: Key, keys: Iterable<Key>): void,
+  moveAfter: (key: Key, keys: Iterable<Key>) => void,
 
   /**
    * Updates an item in the tree.
    * @param key - The key of the item to update.
    * @param newValue - The new value for the item.
    */
-  update(key: Key, newValue: T): void
+  update: (key: Key, newValue: T) => void
 }
 
 interface TreeDataState<T extends object> {
diff --git a/packages/@react-stately/datepicker/src/useDatePickerState.ts b/packages/@react-stately/datepicker/src/useDatePickerState.ts
index ad1506bebf4..0c7f32c765a 100644
--- a/packages/@react-stately/datepicker/src/useDatePickerState.ts
+++ b/packages/@react-stately/datepicker/src/useDatePickerState.ts
@@ -33,21 +33,21 @@ export interface DatePickerState extends OverlayTriggerState, FormValidationStat
   /** The default date. */
   defaultValue: DateValue | null,
   /** Sets the selected date. */
-  setValue(value: DateValue | null): void,
+  setValue: (value: DateValue | null) => void,
   /**
    * The date portion of the value. This may be set prior to `value` if the user has
    * selected a date but has not yet selected a time.
    */
   dateValue: DateValue | null,
   /** Sets the date portion of the value. */
-  setDateValue(value: DateValue): void,
+  setDateValue: (value: DateValue) => void,
   /**
    * The time portion of the value. This may be set prior to `value` if the user has
    * selected a time but has not yet selected a date.
    */
   timeValue: TimeValue | null,
   /** Sets the time portion of the value. */
-  setTimeValue(value: TimeValue): void,
+  setTimeValue: (value: TimeValue) => void,
   /** The granularity for the field, based on the `granularity` prop and current value. */
   granularity: Granularity,
   /** Whether the date picker supports selecting a time, according to the `granularity` prop and current value. */
@@ -55,7 +55,7 @@ export interface DatePickerState extends OverlayTriggerState, FormValidationStat
   /** Whether the calendar popover is currently open. */
   isOpen: boolean,
   /** Sets whether the calendar popover is open. */
-  setOpen(isOpen: boolean): void,
+  setOpen: (isOpen: boolean) => void,
   /**
    * The current validation state of the date picker, based on the `validationState`, `minValue`, and `maxValue` props.
    * @deprecated Use `isInvalid` instead.
@@ -64,9 +64,9 @@ export interface DatePickerState extends OverlayTriggerState, FormValidationStat
   /** Whether the date picker is invalid, based on the `isInvalid`, `minValue`, and `maxValue` props. */
   isInvalid: boolean,
   /** Formats the selected value using the given options. */
-  formatValue(locale: string, fieldOptions: FieldOptions): string,
+  formatValue: (locale: string, fieldOptions: FieldOptions) => string,
   /** Gets a formatter based on state's props. */
-  getDateFormatter(locale: string, formatOptions: FormatterOptions): DateFormatter
+  getDateFormatter: (locale: string, formatOptions: FormatterOptions) => DateFormatter
 }
 
 /**
diff --git a/packages/@react-stately/datepicker/src/useDateRangePickerState.ts b/packages/@react-stately/datepicker/src/useDateRangePickerState.ts
index 18b1231491d..df2817f364b 100644
--- a/packages/@react-stately/datepicker/src/useDateRangePickerState.ts
+++ b/packages/@react-stately/datepicker/src/useDateRangePickerState.ts
@@ -35,27 +35,27 @@ export interface DateRangePickerState extends OverlayTriggerState, FormValidatio
   /** The default selected date range. */
   defaultValue: DateRange | null,
   /** Sets the selected date range. */
-  setValue(value: DateRange | null): void,
+  setValue: (value: DateRange | null) => void,
   /**
    * The date portion of the selected range. This may be set prior to `value` if the user has
    * selected a date range but has not yet selected a time range.
    */
   dateRange: RangeValue<DateValue | null> | null,
   /** Sets the date portion of the selected range. */
-  setDateRange(value: DateRange): void,
+  setDateRange: (value: DateRange) => void,
   /**
    * The time portion of the selected range. This may be set prior to `value` if the user has
    * selected a time range but has not yet selected a date range.
    */
   timeRange: RangeValue<TimeValue | null> | null,
   /** Sets the time portion of the selected range. */
-  setTimeRange(value: TimeRange): void,
+  setTimeRange: (value: TimeRange) => void,
   /** Sets the date portion of either the start or end of the selected range. */
-  setDate(part: 'start' | 'end', value: DateValue | null): void,
+  setDate: (part: 'start' | 'end', value: DateValue | null) => void,
   /** Sets the time portion of either the start or end of the selected range. */
-  setTime(part: 'start' | 'end', value: TimeValue | null): void,
+  setTime: (part: 'start' | 'end', value: TimeValue | null) => void,
   /** Sets the date and time of either the start or end of the selected range. */
-  setDateTime(part: 'start' | 'end', value: DateValue | null): void,
+  setDateTime: (part: 'start' | 'end', value: DateValue | null) => void,
   /** The granularity for the field, based on the `granularity` prop and current value. */
   granularity: Granularity,
   /** Whether the date range picker supports selecting times, according to the `granularity` prop and current value. */
@@ -63,7 +63,7 @@ export interface DateRangePickerState extends OverlayTriggerState, FormValidatio
   /** Whether the calendar popover is currently open. */
   isOpen: boolean,
   /** Sets whether the calendar popover is open. */
-  setOpen(isOpen: boolean): void,
+  setOpen: (isOpen: boolean) => void,
   /**
    * The current validation state of the date range picker, based on the `validationState`, `minValue`, and `maxValue` props.
    * @deprecated Use `isInvalid` instead.
@@ -72,9 +72,9 @@ export interface DateRangePickerState extends OverlayTriggerState, FormValidatio
   /** Whether the date range picker is invalid, based on the `isInvalid`, `minValue`, and `maxValue` props. */
   isInvalid: boolean,
   /** Formats the selected range using the given options. */
-  formatValue(locale: string, fieldOptions: FieldOptions): {start: string, end: string} | null,
+  formatValue: (locale: string, fieldOptions: FieldOptions) => {start: string, end: string} | null,
   /** Gets a formatter based on state's props. */
-  getDateFormatter(locale: string, formatOptions: FormatterOptions): DateFormatter
+  getDateFormatter: (locale: string, formatOptions: FormatterOptions) => DateFormatter
 }
 
 /**
diff --git a/packages/@react-stately/disclosure/src/useDisclosureGroupState.ts b/packages/@react-stately/disclosure/src/useDisclosureGroupState.ts
index ef880baa6e9..d9bbe965b2e 100644
--- a/packages/@react-stately/disclosure/src/useDisclosureGroupState.ts
+++ b/packages/@react-stately/disclosure/src/useDisclosureGroupState.ts
@@ -38,10 +38,10 @@ export interface DisclosureGroupState {
   readonly expandedKeys: Set<Key>,
 
   /** Toggles the expanded state for an item by its key. */
-  toggleKey(key: Key): void,
+  toggleKey: (key: Key) => void,
 
   /** Replaces the set of expanded keys. */
-  setExpandedKeys(keys: Set<Key>): void
+  setExpandedKeys: (keys: Set<Key>) => void
 }
 
 /**
diff --git a/packages/@react-stately/disclosure/src/useDisclosureState.ts b/packages/@react-stately/disclosure/src/useDisclosureState.ts
index c7b0d14b94c..7274e310143 100644
--- a/packages/@react-stately/disclosure/src/useDisclosureState.ts
+++ b/packages/@react-stately/disclosure/src/useDisclosureState.ts
@@ -27,13 +27,13 @@ export interface DisclosureState {
   /** Whether the disclosure is currently expanded. */
   readonly isExpanded: boolean,
   /** Sets whether the disclosure is expanded. */
-  setExpanded(isExpanded: boolean): void,
+  setExpanded: (isExpanded: boolean) => void,
   /** Expand the disclosure. */
-  expand(): void,
+  expand: () => void,
   /** Collapse the disclosure. */
-  collapse(): void,
+  collapse: () => void,
   /** Toggles the disclosure's visibility. */
-  toggle(): void
+  toggle: () => void
 }
 
 /**
diff --git a/packages/@react-stately/dnd/src/useDraggableCollectionState.ts b/packages/@react-stately/dnd/src/useDraggableCollectionState.ts
index 5114fbe22a6..b37f7576ff2 100644
--- a/packages/@react-stately/dnd/src/useDraggableCollectionState.ts
+++ b/packages/@react-stately/dnd/src/useDraggableCollectionState.ts
@@ -35,21 +35,21 @@ export interface DraggableCollectionState {
   /** Whether drag events are disabled. */
   isDisabled?: boolean,
   /** Returns whether the given key is currently being dragged. */
-  isDragging(key: Key): boolean,
+  isDragging: (key: Key) => boolean,
   /** Returns the keys of the items that will be dragged with the given key (e.g. selected items). */
-  getKeysForDrag(key: Key): Set<Key>,
+  getKeysForDrag: (key: Key) => Set<Key>,
   /** Returns the items to drag for the given key. */
-  getItems(key: Key): DragItem[],
+  getItems: (key: Key) => DragItem[],
   /** The ref of the element that will be rendered as the drag preview while dragging. */
   preview?: RefObject<DragPreviewRenderer | null>,
   /** Function that returns the drop operations that are allowed for the dragged items. If not provided, all drop operations are allowed. */
   getAllowedDropOperations?: () => DropOperation[],
   /** Begins a drag for the given key. This triggers the onDragStart event. */
-  startDrag(key: Key, event: DragStartEvent): void,
+  startDrag: (key: Key, event: DragStartEvent) => void,
   /** Triggers an onDragMove event. */
-  moveDrag(event: DragMoveEvent): void,
+  moveDrag: (event: DragMoveEvent) => void,
   /** Ends the current drag, and emits an onDragEnd event. */
-  endDrag(event: DraggableCollectionEndEvent): void
+  endDrag: (event: DraggableCollectionEndEvent) => void
 }
 
 /**
diff --git a/packages/@react-stately/dnd/src/useDroppableCollectionState.ts b/packages/@react-stately/dnd/src/useDroppableCollectionState.ts
index 01036c91688..4cf15209fa4 100644
--- a/packages/@react-stately/dnd/src/useDroppableCollectionState.ts
+++ b/packages/@react-stately/dnd/src/useDroppableCollectionState.ts
@@ -41,11 +41,11 @@ export interface DroppableCollectionState {
   /** Whether drop events are disabled. */
   isDisabled?: boolean,
   /** Sets the current drop target. */
-  setTarget(target: DropTarget | null): void,
+  setTarget: (target: DropTarget | null) => void,
   /** Returns whether the given target is equivalent to the current drop target. */
-  isDropTarget(target: DropTarget | null): boolean,
+  isDropTarget: (target: DropTarget | null) => boolean,
   /** Returns the drop operation for the given parameters. */
-  getDropOperation(e: DropOperationEvent): DropOperation
+  getDropOperation: (e: DropOperationEvent) => DropOperation
 }
 
 /**
diff --git a/packages/@react-stately/form/src/useFormValidationState.ts b/packages/@react-stately/form/src/useFormValidationState.ts
index 83acd2f155f..493f27e65ea 100644
--- a/packages/@react-stately/form/src/useFormValidationState.ts
+++ b/packages/@react-stately/form/src/useFormValidationState.ts
@@ -55,11 +55,11 @@ export interface FormValidationState {
   /** Currently displayed validation results, updated when the user commits their changes. */
   displayValidation: ValidationResult,
   /** Updates the current validation result. Not displayed to the user until `commitValidation` is called. */
-  updateValidation(result: ValidationResult): void,
+  updateValidation: (result: ValidationResult) => void,
   /** Resets the displayed validation state to valid when the user resets the form. */
-  resetValidation(): void,
+  resetValidation: () => void,
   /** Commits the realtime validation so it is displayed to the user. */
-  commitValidation(): void
+  commitValidation: () => void
 }
 
 export function useFormValidationState<T>(props: FormValidationProps<T>): FormValidationState {
diff --git a/packages/@react-stately/list/src/useSingleSelectListState.ts b/packages/@react-stately/list/src/useSingleSelectListState.ts
index b99a98af8ad..2d0ecefc0ab 100644
--- a/packages/@react-stately/list/src/useSingleSelectListState.ts
+++ b/packages/@react-stately/list/src/useSingleSelectListState.ts
@@ -27,7 +27,7 @@ export interface SingleSelectListState<T> extends ListState<T> {
   readonly selectedKey: Key | null,
 
   /** Sets the selected key. */
-  setSelectedKey(key: Key | null): void,
+  setSelectedKey: (key: Key | null) => void,
 
   /** The value of the currently selected item. */
   readonly selectedItem: Node<T> | null
diff --git a/packages/@react-stately/menu/src/useMenuTriggerState.ts b/packages/@react-stately/menu/src/useMenuTriggerState.ts
index 0901c052323..5033741dde5 100644
--- a/packages/@react-stately/menu/src/useMenuTriggerState.ts
+++ b/packages/@react-stately/menu/src/useMenuTriggerState.ts
@@ -20,10 +20,10 @@ export interface MenuTriggerState extends OverlayTriggerState {
   readonly focusStrategy: FocusStrategy | null,
 
   /** Opens the menu. */
-  open(focusStrategy?: FocusStrategy | null): void,
+  open: (focusStrategy?: FocusStrategy | null) => void,
 
   /** Toggles the menu. */
-  toggle(focusStrategy?: FocusStrategy | null): void
+  toggle: (focusStrategy?: FocusStrategy | null) => void
 }
 
 export interface RootMenuTriggerState extends MenuTriggerState {
diff --git a/packages/@react-stately/numberfield/src/useNumberFieldState.ts b/packages/@react-stately/numberfield/src/useNumberFieldState.ts
index 9902a739c6a..6c6b21edf5f 100644
--- a/packages/@react-stately/numberfield/src/useNumberFieldState.ts
+++ b/packages/@react-stately/numberfield/src/useNumberFieldState.ts
@@ -42,26 +42,26 @@ export interface NumberFieldState extends FormValidationState {
    * Values can be partially entered, and may be valid even if they cannot currently be parsed to a number.
    * Can be used to implement validation as a user types.
    */
-  validate(value: string): boolean,
+  validate: (value: string) => boolean,
   /** Sets the current text value of the input. */
-  setInputValue(val: string): void,
+  setInputValue: (val: string) => void,
   /** Sets the number value. */
-  setNumberValue(val: number): void,
+  setNumberValue: (val: number) => void,
   /**
    * Commits the current input value. The value is parsed to a number, clamped according
    * to the minimum and maximum values of the field, and snapped to the nearest step value.
    * This will fire the `onChange` prop with the new value, and if uncontrolled, update the `numberValue`.
    * Typically this is called when the field is blurred.
    */
-  commit(): void,
+  commit: () => void,
   /** Increments the current input value to the next step boundary, and fires `onChange`. */
-  increment(): void,
+  increment: () => void,
   /** Decrements the current input value to the next step boundary, and fires `onChange`. */
-  decrement(): void,
+  decrement: () => void,
   /** Sets the current value to the `maxValue` if any, and fires `onChange`. */
-  incrementToMax(): void,
+  incrementToMax: () => void,
   /** Sets the current value to the `minValue` if any, and fires `onChange`. */
-  decrementToMin(): void
+  decrementToMin: () => void
 }
 
 export interface NumberFieldStateOptions extends NumberFieldProps {
diff --git a/packages/@react-stately/overlays/src/useOverlayTriggerState.ts b/packages/@react-stately/overlays/src/useOverlayTriggerState.ts
index 8e698afeea2..7dfa434c2a4 100644
--- a/packages/@react-stately/overlays/src/useOverlayTriggerState.ts
+++ b/packages/@react-stately/overlays/src/useOverlayTriggerState.ts
@@ -18,13 +18,13 @@ export interface OverlayTriggerState {
   /** Whether the overlay is currently open. */
   readonly isOpen: boolean,
   /** Sets whether the overlay is open. */
-  setOpen(isOpen: boolean): void,
+  setOpen: (isOpen: boolean) => void,
   /** Opens the overlay. */
-  open(): void,
+  open: () => void,
   /** Closes the overlay. */
-  close(): void,
+  close: () => void,
   /** Toggles the overlay's visibility. */
-  toggle(): void
+  toggle: () => void
 }
 
 /**
diff --git a/packages/@react-stately/radio/src/useRadioGroupState.ts b/packages/@react-stately/radio/src/useRadioGroupState.ts
index 003e9f5e5d9..a4a47683cb5 100644
--- a/packages/@react-stately/radio/src/useRadioGroupState.ts
+++ b/packages/@react-stately/radio/src/useRadioGroupState.ts
@@ -49,13 +49,13 @@ export interface RadioGroupState extends FormValidationState {
   readonly defaultSelectedValue: string | null,
 
   /** Sets the selected value. */
-  setSelectedValue(value: string | null): void,
+  setSelectedValue: (value: string | null) => void,
 
   /** The value of the last focused radio. */
   readonly lastFocusedValue: string | null,
 
   /** Sets the last focused value. */
-  setLastFocusedValue(value: string | null): void
+  setLastFocusedValue: (value: string | null) => void
 }
 
 let instance = Math.round(Math.random() * 10000000000);
diff --git a/packages/@react-stately/searchfield/src/useSearchFieldState.ts b/packages/@react-stately/searchfield/src/useSearchFieldState.ts
index 3a338cf6ef0..8b099867a63 100644
--- a/packages/@react-stately/searchfield/src/useSearchFieldState.ts
+++ b/packages/@react-stately/searchfield/src/useSearchFieldState.ts
@@ -18,7 +18,7 @@ export interface SearchFieldState {
   readonly value: string,
 
   /** Sets the value of the search field. */
-  setValue(value: string): void
+  setValue: (value: string) => void
 }
 
 /**
diff --git a/packages/@react-stately/select/src/useSelectState.ts b/packages/@react-stately/select/src/useSelectState.ts
index cdab4312f40..24e01e12e25 100644
--- a/packages/@react-stately/select/src/useSelectState.ts
+++ b/packages/@react-stately/select/src/useSelectState.ts
@@ -27,16 +27,16 @@ export interface SelectState<T> extends SingleSelectListState<T>, OverlayTrigger
   readonly isFocused: boolean,
 
   /** Sets whether the select is focused. */
-  setFocused(isFocused: boolean): void,
+  setFocused: (isFocused: boolean) => void,
 
   /** Controls which item will be auto focused when the menu opens. */
   readonly focusStrategy: FocusStrategy | null,
 
   /** Opens the menu. */
-  open(focusStrategy?: FocusStrategy | null): void,
+  open: (focusStrategy?: FocusStrategy | null) => void,
 
   /** Toggles the menu. */
-  toggle(focusStrategy?: FocusStrategy | null): void
+  toggle: (focusStrategy?: FocusStrategy | null) => void
 }
 
 /**
diff --git a/packages/@react-stately/selection/src/types.ts b/packages/@react-stately/selection/src/types.ts
index 8eafe03307b..35325c3dfd1 100644
--- a/packages/@react-stately/selection/src/types.ts
+++ b/packages/@react-stately/selection/src/types.ts
@@ -17,13 +17,13 @@ export interface FocusState {
   /** Whether the collection is currently focused. */
   readonly isFocused: boolean,
   /** Sets whether the collection is focused. */
-  setFocused(isFocused: boolean): void,
+  setFocused: (isFocused: boolean) => void,
   /** The current focused key in the collection. */
   readonly focusedKey: Key | null,
   /** Whether the first or last child of the focused key should receive focus. */
   readonly childFocusStrategy: FocusStrategy | null,
   /** Sets the focused key, and optionally, whether the first or last child of that key should receive focus. */
-  setFocusedKey(key: Key | null, child?: FocusStrategy): void
+  setFocusedKey: (key: Key | null, child?: FocusStrategy) => void
 }
 
 export interface SingleSelectionState extends FocusState {
@@ -32,7 +32,7 @@ export interface SingleSelectionState extends FocusState {
   /** The currently selected key in the collection. */
   readonly selectedKey: Key,
   /** Sets the selected key in the collection. */
-  setSelectedKey(key: Key | null): void
+  setSelectedKey: (key: Key | null) => void
 }
 
 export interface MultipleSelectionState extends FocusState {
@@ -41,13 +41,13 @@ export interface MultipleSelectionState extends FocusState {
   /** The selection behavior for the collection. */
   readonly selectionBehavior: SelectionBehavior,
   /** Sets the selection behavior for the collection. */
-  setSelectionBehavior(selectionBehavior: SelectionBehavior): void,
+  setSelectionBehavior: (selectionBehavior: SelectionBehavior) => void,
   /** Whether the collection allows empty selection. */
   readonly disallowEmptySelection: boolean,
   /** The currently selected keys in the collection. */
   readonly selectedKeys: Selection,
   /** Sets the selected keys in the collection. */
-  setSelectedKeys(keys: Selection): void,
+  setSelectedKeys: (keys: Selection) => void,
   /** The currently disabled keys in the collection. */
   readonly disabledKeys: Set<Key>,
   /** Whether `disabledKeys` applies to selection, actions, or both. */
@@ -76,38 +76,38 @@ export interface MultipleSelectionManager extends FocusState {
   /** Whether `disabledKeys` applies to selection, actions, or both. */
   readonly disabledBehavior: DisabledBehavior,
   /** Returns whether a key is selected. */
-  isSelected(key: Key): boolean,
+  isSelected: (key: Key) => boolean,
   /** Returns whether the current selection is equal to the given selection. */
-  isSelectionEqual(selection: Set<Key>): boolean,
+  isSelectionEqual: (selection: Set<Key>) => boolean,
   /** Extends the selection to the given key. */
-  extendSelection(toKey: Key): void,
+  extendSelection: (toKey: Key) => void,
   /** Toggles whether the given key is selected. */
-  toggleSelection(key: Key): void,
+  toggleSelection: (key: Key) => void,
   /** Replaces the selection with only the given key. */
-  replaceSelection(key: Key): void,
+  replaceSelection: (key: Key) => void,
   /** Replaces the selection with the given keys. */
-  setSelectedKeys(keys: Iterable<Key>): void,
+  setSelectedKeys: (keys: Iterable<Key>) => void,
   /** Selects all items in the collection. */
-  selectAll(): void,
+  selectAll: () => void,
   /** Removes all keys from the selection. */
-  clearSelection(): void,
+  clearSelection: () => void,
   /** Toggles between select all and an empty selection. */
-  toggleSelectAll(): void,
+  toggleSelectAll: () => void,
   /**
    * Toggles, replaces, or extends selection to the given key depending
    * on the pointer event and collection's selection mode.
    */
-  select(key: Key, e?: PressEvent | LongPressEvent | PointerEvent): void,
+  select: (key: Key, e?: PressEvent | LongPressEvent | PointerEvent) => void,
   /** Returns whether the given key can be selected. */
-  canSelectItem(key: Key): boolean,
+  canSelectItem: (key: Key) => boolean,
   /** Returns whether the given key is non-interactive, i.e. both selection and actions are disabled. */
-  isDisabled(key: Key): boolean,
+  isDisabled: (key: Key) => boolean,
   /** Sets the selection behavior for the collection. */
-  setSelectionBehavior(selectionBehavior: SelectionBehavior): void,
+  setSelectionBehavior: (selectionBehavior: SelectionBehavior) => void,
   /** Returns whether the given key is a hyperlink. */
-  isLink(key: Key): boolean,
+  isLink: (key: Key) => boolean,
   /** Returns the props for the given item. */
-  getItemProps(key: Key): any,
+  getItemProps: (key: Key) => any,
   /** The collection of nodes that the selection manager handles. */
   collection: Collection<Node<unknown>>
 }
diff --git a/packages/@react-stately/slider/src/useSliderState.ts b/packages/@react-stately/slider/src/useSliderState.ts
index 0f7350fc9a5..821a7559e54 100644
--- a/packages/@react-stately/slider/src/useSliderState.ts
+++ b/packages/@react-stately/slider/src/useSliderState.ts
@@ -28,7 +28,7 @@ export interface SliderState {
    * Get the value for the specified thumb.
    * @param index
    */
-  getThumbValue(index: number): number,
+  getThumbValue: (index: number) => number,
 
   /**
    * Sets the value for the specified thumb.
@@ -36,26 +36,26 @@ export interface SliderState {
    * @param index
    * @param value
    */
-  setThumbValue(index: number, value: number): void,
+  setThumbValue: (index: number, value: number) => void,
 
   /**
    * Sets value for the specified thumb by percent offset (between 0 and 1).
    * @param index
    * @param percent
    */
-  setThumbPercent(index: number, percent: number): void,
+  setThumbPercent: (index: number, percent: number) => void,
 
   /**
    * Whether the specific thumb is being dragged.
    * @param index
    */
-  isThumbDragging(index: number): boolean,
+  isThumbDragging: (index: number) => boolean,
   /**
    * Set is dragging on the specified thumb.
    * @param index
    * @param dragging
    */
-  setThumbDragging(index: number, dragging: boolean): void,
+  setThumbDragging: (index: number, dragging: boolean) => void,
 
   /**
    * Currently-focused thumb index.
@@ -66,71 +66,71 @@ export interface SliderState {
    * any thumb that had it before.
    * @param index
    */
-  setFocusedThumb(index: number | undefined): void,
+  setFocusedThumb: (index: number | undefined) => void,
 
   /**
    * Returns the specified thumb's value as a percentage from 0 to 1.
    * @param index
    */
-  getThumbPercent(index: number): number,
+  getThumbPercent: (index: number) => number,
 
   /**
    * Returns the value as a percent between the min and max of the slider.
    * @param index
    */
-  getValuePercent(value: number): number,
+  getValuePercent: (value: number) => number,
 
   /**
    * Returns the string label for the specified thumb's value, per props.formatOptions.
    * @param index
    */
-  getThumbValueLabel(index: number): string,
+  getThumbValueLabel: (index: number) => string,
 
   /**
    * Returns the string label for the value, per props.formatOptions.
    * @param index
    */
-  getFormattedValue(value: number): string,
+  getFormattedValue: (value: number) => string,
 
   /**
    * Returns the min allowed value for the specified thumb.
    * @param index
    */
-  getThumbMinValue(index: number): number,
+  getThumbMinValue: (index: number) => number,
 
   /**
    * Returns the max allowed value for the specified thumb.
    * @param index
    */
-  getThumbMaxValue(index: number): number,
+  getThumbMaxValue: (index: number) => number,
 
   /**
    * Converts a percent along track (between 0 and 1) to the corresponding value.
    * @param percent
    */
-  getPercentValue(percent: number): number,
+  getPercentValue: (percent: number) => number,
 
   /**
    * Returns if the specified thumb is editable.
    * @param index
    */
-  isThumbEditable(index: number): boolean,
+  isThumbEditable: (index: number) => boolean,
 
   /**
    * Set the specified thumb's editable state.
    * @param index
    * @param editable
    */
-  setThumbEditable(index: number, editable: boolean): void,
+  setThumbEditable: (index: number, editable: boolean) => void,
 
   /**
    * Increments the value of the thumb by the step or page amount.
    */
-  incrementThumb(index: number, stepSize?: number): void,
+  incrementThumb: (index: number, stepSize?: number) => void,
   /**
    * Decrements the value of the thumb by the step or page amount.
    */
-  decrementThumb(index: number, stepSize?: number): void,
+  decrementThumb: (index: number, stepSize?: number) => void,
 
   /**
    * The step amount for the slider.
diff --git a/packages/@react-stately/steplist/src/useStepListState.ts b/packages/@react-stately/steplist/src/useStepListState.ts
index f2957971b44..36e4d11fbe4 100644
--- a/packages/@react-stately/steplist/src/useStepListState.ts
+++ b/packages/@react-stately/steplist/src/useStepListState.ts
@@ -32,9 +32,9 @@ export interface StepListProps<T> extends CollectionBase<T>, Omit<SingleSelectio
 
 export interface StepListState<T> extends SingleSelectListState<T> {
   readonly lastCompletedStep?: Key,
-  setLastCompletedStep(key: Key): void,
-  isCompleted(key: Key): boolean,
-  isSelectable(key: Key): boolean
+  setLastCompletedStep: (key: Key) => void,
+  isCompleted: (key: Key) => boolean,
+  isSelectable: (key: Key) => boolean
 }
 
 export function useStepListState<T extends object>(props: StepListProps<T>): StepListState<T> {
diff --git a/packages/@react-stately/table/src/useTableState.ts b/packages/@react-stately/table/src/useTableState.ts
index 0addeb10a35..2c53e094c99 100644
--- a/packages/@react-stately/table/src/useTableState.ts
+++ b/packages/@react-stately/table/src/useTableState.ts
@@ -26,7 +26,7 @@ export interface TableState<T> extends GridState<T, ITableCollection<T>> {
   /** The current sorted column and direction. */
   sortDescriptor: SortDescriptor | null,
   /** Calls the provided onSortChange handler with the provided column key and sort direction. */
-  sort(columnKey: Key, direction?: 'ascending' | 'descending'): void,
+  sort: (columnKey: Key, direction?: 'ascending' | 'descending') => void,
   /** Whether keyboard navigation is disabled, such as when the arrow keys should be handled by a component within a cell. */
   isKeyboardNavigationDisabled: boolean,
   /** Set whether keyboard navigation is disabled, such as when the arrow keys should be handled by a component within a cell. */
diff --git a/packages/@react-stately/table/src/useTreeGridState.ts b/packages/@react-stately/table/src/useTreeGridState.ts
index 3e6e3247927..1462fa14a48 100644
--- a/packages/@react-stately/table/src/useTreeGridState.ts
+++ b/packages/@react-stately/table/src/useTreeGridState.ts
@@ -23,7 +23,7 @@ export interface TreeGridState<T> extends TableState<T> {
   /** A set of keys for items that are expanded. */
   expandedKeys: 'all' | Set<Key>,
   /** Toggles the expanded state for a row by its key. */
-  toggleKey(key: Key): void,
+  toggleKey: (key: Key) => void,
   /** The key map containing nodes representing the collection's tree grid structure. */
   keyMap: Map<Key, GridNode<T>>,
   /** The number of leaf columns provided by the user. */
diff --git a/packages/@react-stately/toast/src/useToastState.ts b/packages/@react-stately/toast/src/useToastState.ts
index 2691f637f67..e6762e81d2a 100644
--- a/packages/@react-stately/toast/src/useToastState.ts
+++ b/packages/@react-stately/toast/src/useToastState.ts
@@ -40,15 +40,15 @@ export interface QueuedToast<T> extends ToastOptions {
 
 export interface ToastState<T> {
   /** Adds a new toast to the queue. */
-  add(content: T, options?: ToastOptions): string,
+  add: (content: T, options?: ToastOptions) => string,
   /**
    * Closes a toast.
    */
-  close(key: string): void,
+  close: (key: string) => void,
   /** Pauses the timers for all visible toasts. */
-  pauseAll(): void,
+  pauseAll: () => void,
   /** Resumes the timers for all visible toasts. */
-  resumeAll(): void,
+  resumeAll: () => void,
   /** The visible toasts. */
   visibleToasts: QueuedToast<T>[]
 }
diff --git a/packages/@react-stately/toggle/src/useToggleGroupState.ts b/packages/@react-stately/toggle/src/useToggleGroupState.ts
index 7e5c3b5d529..4cae555e4af 100644
--- a/packages/@react-stately/toggle/src/useToggleGroupState.ts
+++ b/packages/@react-stately/toggle/src/useToggleGroupState.ts
@@ -40,13 +40,13 @@ export interface ToggleGroupState {
   readonly selectedKeys: Set<Key>,
 
   /** Toggles the selected state for an item by its key. */
-  toggleKey(key: Key): void,
+  toggleKey: (key: Key) => void,
 
   /** Sets whether the given key is selected. */
-  setSelected(key: Key, isSelected: boolean): void,
+  setSelected: (key: Key, isSelected: boolean) => void,
 
   /** Replaces the set of selected keys. */
-  setSelectedKeys(keys: Set<Key>): void
+  setSelectedKeys: (keys: Set<Key>) => void
 }
 
 /**
diff --git a/packages/@react-stately/toggle/src/useToggleState.ts b/packages/@react-stately/toggle/src/useToggleState.ts
index 3e606ec3951..247debcd9c1 100644
--- a/packages/@react-stately/toggle/src/useToggleState.ts
+++ b/packages/@react-stately/toggle/src/useToggleState.ts
@@ -24,10 +24,10 @@ export interface ToggleState {
   readonly defaultSelected: boolean,
 
   /** Updates selection state. */
-  setSelected(isSelected: boolean): void,
+  setSelected: (isSelected: boolean) => void,
 
   /** Toggle the selection state. */
-  toggle(): void
+  toggle: () => void
 }
 
 /**
diff --git a/packages/@react-stately/tooltip/src/useTooltipTriggerState.ts b/packages/@react-stately/tooltip/src/useTooltipTriggerState.ts
index 32227e8ba60..388264a2f6e 100644
--- a/packages/@react-stately/tooltip/src/useTooltipTriggerState.ts
+++ b/packages/@react-stately/tooltip/src/useTooltipTriggerState.ts
@@ -25,9 +25,9 @@ export interface TooltipTriggerState {
    * depending on a global warmup timer. The `immediate` option shows the
    * tooltip immediately instead.
    */
-  open(immediate?: boolean): void,
+  open: (immediate?: boolean) => void,
   /** Hides the tooltip. */
-  close(immediate?: boolean): void
+  close: (immediate?: boolean) => void
 }
 
 let tooltips = {};
diff --git a/packages/@react-stately/tree/src/useTreeState.ts b/packages/@react-stately/tree/src/useTreeState.ts
index c454a13a9fe..a8cead6c696 100644
--- a/packages/@react-stately/tree/src/useTreeState.ts
+++ b/packages/@react-stately/tree/src/useTreeState.ts
@@ -32,10 +32,10 @@ export interface TreeState<T> {
   readonly expandedKeys: Set<Key>,
 
   /** Toggles the expanded state for an item by its key. */
-  toggleKey(key: Key): void,
+  toggleKey: (key: Key) => void,
 
   /** Replaces the set of expanded keys. */
-  setExpandedKeys(keys: Set<Key>): void,
+  setExpandedKeys: (keys: Set<Key>) => void,
 
   /** A selection manager to read and update multiple selection state. */
   readonly selectionManager: SelectionManager
diff --git a/packages/@react-stately/virtualizer/src/useVirtualizerState.ts b/packages/@react-stately/virtualizer/src/useVirtualizerState.ts
index 9844e2acdd0..3408ab28c44 100644
--- a/packages/@react-stately/virtualizer/src/useVirtualizerState.ts
+++ b/packages/@react-stately/virtualizer/src/useVirtualizerState.ts
@@ -21,10 +21,10 @@ import {useLayoutEffect} from '@react-aria/utils';
 import {Virtualizer} from './Virtualizer';
 
 interface VirtualizerProps<T extends object, V, O> {
-  renderView(type: string, content: T | null): V,
+  renderView: (type: string, content: T | null) => V,
   layout: Layout<T>,
   collection: Collection<T>,
-  onVisibleRectChange(rect: Rect): void,
+  onVisibleRectChange: (rect: Rect) => void,
   persistedKeys?: Set<Key> | null,
   layoutOptions?: O
 }