Removed a section

chongruei · Apr 15, 2024 · b9a0589 · b9a0589
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commit b9a0589
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diff --git a/book-content/chapters/16-the-utils-folder.md b/book-content/chapters/16-the-utils-folder.md
@@ -302,102 +302,9 @@ Note how clever TypeScript is being here. Even though we didn't specify a return
 
 <!-- CONTINUE -->
 
-### Combining Generic Types and Functions
+### Type Safe vs Type Faith
 
-Generic functions are useful on their own, but they really start to shine when combined with generic types. Let's look at a real-world example of how flexible this combination can be.
-
-Here we have a regular, non-generic function that fetches an `Album`'s data from an API:
-
-```typescript
-type Album = {
-  id: number;
-  title: string;
-  artist: string;
-  year: number;
-};
-
-async function fetchAlbum(id: number): Promise<Album> {
-  const response = await fetch(`https://api.example.com/albums/${id}`);
-  return response.json();
-}
-```
-
-If we wanted to fetch a `Song` or a `Playlist`, we would need to create similar functions with different types:
-
-```typescript
-type Song = {
-  id: number;
-  title: string;
-  duration: number;
-};
-
-type Playlist = {
-  id: number;
-  name: string;
-  songs: Song[];
-};
-
-async function fetchSong(id: number): Promise<Song> {
-  const response = await fetch(`https://api.example.com/songs/${id}`);
-  return response.json();
-}
-
-async function fetchPlaylist(id: number): Promise<Playlist> {
-  const response = await fetch(`https://api.example.com/playlists/${id}`);
-  return response.json();
-}
-```
-
-These functions are almost identical, with the only difference being the type of data being fetched and the URL endpoint. This is a perfect opportunity to bring in generic types and functions.
-
-#### Refactoring to be Generic
-
-To start, we'll make a generic `ApiResponse` type that represents the structure of the API response. This type will take a type parameter `T` to represent the type of data being returned, as well as a `status` and `message` property for additional metadata:
-
-```typescript
-type ApiResponse<T> = {
-  data: T;
-  status: number;
-  message: string;
-};
-```
-
-This `ApiResponse` type will support the `Album`, `Song`, and `Playlist` types, and ensure that all API responses have a consistent structure.
-
-Next, we'll create a generic function that can fetch any type of data from the API. The `fetchData` function will take in a type parameter `T` that corresponds to `Album`, `Song`, or `Playlist`, along with an `endpoint` parameter that specifies the API endpoint. The return type will be a `Promise` that resolves to an `ApiResponse` object for the same type `T` being passed in:
-
-```typescript
-async function fetchData<T>(endpoint: string): Promise<ApiResponse<T>> {
-  const response = await fetch(`https://api.example.com/${endpoint}`);
-  const data = await response.json();
-  return {
-    data,
-    status: response.status,
-    message: response.statusText,
-  };
-}
-```
-
-Now we can use the generic `fetchData` function with any of our types by specifying the type argument and the endpoint:
-
-```typescript
-async function getAlbum(id: number): Promise<Album> {
-  const response = await fetchData<Album>(`albums/${id}`);
-  return response.data;
-}
-
-async function getSong(id: number): Promise<Song> {
-  const response = await fetchData<Song>(`songs/${id}`);
-  return response.data;
-}
-
-async function getPlaylist(id: number): Promise<Playlist> {
-  const response = await fetchData<Playlist>(`playlists/${id}`);
-  return response.data;
-}
-```
-
-Each function will return the fetched data of the specified type, and the `ApiResponse` type ensures that the response has a consistent structure.
+<!-- TODO -->
 
 ## Type Predicates