feat: simplified types for Serialize

.changeset/lemon-beers-fetch.md

@@ -0,0 +1,24 @@
+---
+"@remix-run/server-runtime": minor
+"@remix-run/react": minor
+---
+
+Force Typescript to simplify type produced by `Serialize`.
+
+As a result, the following types and functions have simplified return types:
+- SerializeFrom
+- useLoaderData
+- useActionData
+- useFetcher
+
+```ts
+type Data = { hello: string; when: Date }
+
+// BEFORE
+type Unsimplified = SerializeFrom<Data>
+//   ^? SerializeObject<UndefinedToOptional<{ hello: string; when: Date }>>
+
+// AFTER
+type Simplified = SerializeFrom<Data>
+//   ^? { hello: string; when: string }
+```

packages/remix-server-runtime/serialize.ts

@@ -1,6 +1,9 @@
 import type { AppData } from "./data";
 import type { TypedDeferredData, TypedResponse } from "./responses";
 
+// force Typescript to simplify the type
+type Pretty<T> = { [K in keyof T]: T[K] } & {};
+
 type JsonPrimitive =
   | string
   | number
@@ -18,7 +21,7 @@ type NonJsonPrimitive = undefined | Function | symbol;
 type IsAny<T> = 0 extends 1 & T ? true : false;
 
 // prettier-ignore
-type Serialize<T> =
+type Serialize<T> = Pretty<
   IsAny<T> extends true ? any :
   T extends TypedDeferredData<infer U> ? SerializeDeferred<U> :
   T extends JsonPrimitive ? T :
@@ -28,7 +31,8 @@ type Serialize<T> =
   T extends [unknown, ...unknown[]] ? SerializeTuple<T> :
   T extends ReadonlyArray<infer U> ? (U extends NonJsonPrimitive ? null : Serialize<U>)[] :
   T extends object ? SerializeObject<UndefinedToOptional<T>> :
-  never;
+  never
+>;
 
 /** JSON serialize [tuples](https://www.typescriptlang.org/docs/handbook/2/objects.html#tuple-types) */
 type SerializeTuple<T extends [unknown, ...unknown[]]> = {