Use union for AsyncState type

Author: adipascu

src/index.ts

@@ -43,12 +43,31 @@ export type AsyncStateStatus =
   | 'success'
   | 'error';
 
-export type AsyncState<R> = {
-  status: AsyncStateStatus;
-  loading: boolean;
-  error: Error | undefined;
-  result: R | undefined;
-};
+export declare type AsyncState<R> =
+  | {
+      status: 'not-requested';
+      loading: false;
+      result: undefined;
+      error: undefined;
+    }
+  | {
+      status: 'loading';
+      loading: true;
+      error: undefined;
+      result: undefined;
+    }
+  | {
+      status: 'success';
+      loading: false;
+      error: undefined;
+      result: R;
+    }
+  | {
+      status: 'error';
+      loading: false;
+      error: Error;
+      result: undefined;
+    };
 type SetLoading<R> = (asyncState: AsyncState<R>) => AsyncState<R>;
 type SetResult<R> = (result: R, asyncState: AsyncState<R>) => AsyncState<R>;
 type SetError<R> = (error: Error, asyncState: AsyncState<R>) => AsyncState<R>;