From 5484a491668df1313d84b1e02e0221c62a6bc43c Mon Sep 17 00:00:00 2001
From: Yingchi Long <i@lyc.dev>
Date: Fri, 19 Jul 2024 18:08:07 +0800
Subject: [PATCH] functional: add undefined checker

---
 src/functional.ts | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/functional.ts b/src/functional.ts
index 05c4e57..46ca2d4 100644
--- a/src/functional.ts
+++ b/src/functional.ts
@@ -6,3 +6,11 @@ export const sequence = <T, U>(fn: ($: T) => Promise<U>) => async (L: T[]) => {
 export const parallel = <T, U>(fn: ($: T) => Promise<U>) => async (L: T[]) => {
     await Promise.all(L.map(fn));
 };
+
+
+export const notUndefined: <T>($: T | undefined) => T = $ => {
+    if ($ === undefined)
+        throw Error('the value is undefined!');
+    else
+        return $;
+};