diff --git a/.prettierrc b/.prettierrc
new file mode 100644
index 0000000..74b52b1
--- /dev/null
+++ b/.prettierrc
@@ -0,0 +1,7 @@
+{
+  "arrowParens": "always",
+  "bracketSpacing": true,
+  "singleQuote": true,
+  "tabWidth": 2,
+  "useTabs": true
+}
diff --git a/src/data.ts b/src/data.ts
index e69de29..0d2deca 100644
--- a/src/data.ts
+++ b/src/data.ts
@@ -0,0 +1 @@
+let users: Record<string, Carpool.User> = {};
diff --git a/src/types.ts b/src/types.ts
index 1d1cfff..f03185b 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -1,24 +1,24 @@
 namespace Carpool {
-	interface Group {
+	export interface Group {
 		id: string;
 		member_ids: string[];
 	}
 
-	interface User {
+	export interface User {
 		id: string;
 		first_name: string;
 		last_name: string;
 	}
 
-	interface Comment {
+	export interface Comment {
 		id: string;
 		body: string;
 		author_id: string;
 	}
 
-	type Status = "pending" | "cancelled" | "completed" | "interrupted";
+	export type Status = "pending" | "cancelled" | "completed" | "interrupted";
 
-	interface Post {
+	export interface Post {
 		id: string;
 		title: string;
 		description: string;