diff --git a/ts/types/MapAsync.ts b/ts/types/MapAsync.ts
new file mode 100644
index 000000000..538adfe9d
--- /dev/null
+++ b/ts/types/MapAsync.ts
@@ -0,0 +1,4 @@
+/**
+ * @prettier
+ */
+export type MapAsync<T> = (value: T) => Promise<T>;