From 24860c9a02ff8b6a347ec0cf598f150e9d91ac3e Mon Sep 17 00:00:00 2001
From: Jon Staab <shtaab@gmail.com>
Date: Wed, 12 Nov 2025 11:06:13 -0800
Subject: [PATCH] Add prepend util

---
 docs/lib/tools.md         | 3 +++
 packages/lib/src/Tools.ts | 8 ++++++++
 2 files changed, 11 insertions(+)

diff --git a/docs/lib/tools.md b/docs/lib/tools.md
index b5a9175..f4c746b 100644
--- a/docs/lib/tools.md
+++ b/docs/lib/tools.md
@@ -218,6 +218,9 @@ export declare const take: <T>(n: number, xs: Iterable<T>) => T[];
 // Concatenates multiple arrays, filtering out null/undefined
 export declare const concat: <T>(...xs: T[][]) => T[];
 
+// Prepends element to array
+export declare const prepend: <T>(x: T, xs: T[]) => T[];
+
 // Appends element to array
 export declare const append: <T>(x: T, xs: T[]) => T[];
 
diff --git a/packages/lib/src/Tools.ts b/packages/lib/src/Tools.ts
index 0166738..be0d299 100644
--- a/packages/lib/src/Tools.ts
+++ b/packages/lib/src/Tools.ts
@@ -430,6 +430,14 @@ export const concat = <T>(...xs: T[][]) => xs.flatMap(x => (x === undefined ? []
  */
 export const append = <T>(x: T, xs: Iterable<T>) => concat(Array.from(xs), [x])
 
+/**
+ * Prepends element to array
+ * @param x - Element to prepend
+ * @param xs - Array to prepend to
+ * @returns New array with element prepended
+ */
+export const prepend = <T>(x: T, xs: Iterable<T>) => concat([x], Array.from(xs))
+
 /**
  * Creates union of two arrays
  * @param a - First array