deprecate watch and derive (#1190)

Author: dai-shi

docs/api/utils/derive.mdx

@@ -7,6 +7,11 @@ description: 'create a new proxy derived from others'
 
 ## `derive`
 
+> **⚠️ Deprecated**
+>
+> This package is no longer maintained. Please migrate to
+> [valtio-reactive](https://github.com/valtiojs/valtio-reactive).
+
 ## Installation
 
 ```bash

docs/api/utils/watch.mdx

@@ -7,6 +7,11 @@ description: 'watch for changes.'
 
 # `watch`
 
+> **⚠️ Deprecated**
+>
+> This util is no longer maintained. Please migrate to
+> [valtio-reactive](https://github.com/valtiojs/valtio-reactive).
+
 ## Subscription via a getter
 
 This utility supports subscribing to multiple proxy objects (unlike `subscribe` which listens to only a single proxy). Proxy objects are subscribed with a `get` function passed to the callback.

src/vanilla/utils/watch.ts

@@ -11,9 +11,13 @@ type WatchOptions = {
 
 let currentCleanups: Set<Cleanup> | undefined
 
+let didWarnDeprecation = false
+
 /**
  * watch
  *
+ * @deprecated This util is no longer maintained. Please migrate to [valtio-reactive](https://github.com/valtiojs/valtio-reactive).
+ *
  * Creates a reactive effect that automatically tracks proxy objects and
  * reevaluates everytime one of the tracked proxy objects updates. It returns
  * a cleanup function to stop the reactive effect from reevaluating.
@@ -34,6 +38,13 @@ export function watch(
   callback: WatchCallback,
   options?: WatchOptions,
 ): Cleanup {
+  if (import.meta.env?.MODE !== 'production' && !didWarnDeprecation) {
+    console.warn(
+      '[DEPRECATED] The `watch` util is no longer maintained. Please migrate to [valtio-reactive](https://github.com/valtiojs/valtio-reactive).',
+    )
+    didWarnDeprecation = true
+  }
+
   let alive = true
   const cleanups = new Set<Cleanup>()