From fb1a841526fdade488152f7ed8b0f753eb51bfbe Mon Sep 17 00:00:00 2001
From: Ray Epps <rayepps@Rays-MacBook-Air.local>
Date: Tue, 20 Feb 2024 21:23:45 -0700
Subject: [PATCH] fix partial typing

---
 src/curry.ts            | 23 +++++++++++++++++++----
 src/tests/curry.test.ts |  3 ++-
 2 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/src/curry.ts b/src/curry.ts
index cb76ceec..7d3fd573 100644
--- a/src/curry.ts
+++ b/src/curry.ts
@@ -380,13 +380,28 @@ export function compose(...funcs: ((...args: any[]) => any)[]) {
   return funcs.reverse().reduce((acc, fn) => fn(acc))
 }
 
-export const partial = <T extends any[], R>(
+/**
+ * This type produces the type array of TItems with all the type items
+ * in TItemsToRemove removed from the start of the array type.
+ *
+ * @example
+ * ```
+ * RemoveItemsInFront<[number, number], [number]> = [number]
+ * RemoveItemsInFront<[File, number, string], [File, number]> = [string]
+ * ```
+ */
+type RemoveItemsInFront<
+  TItems extends any[],
+  TItemsToRemove extends any[]
+> = TItems extends [...TItemsToRemove, ...infer TRest] ? TRest : TItems
+
+export const partial = <T extends any[], TA extends Partial<T>, R>(
   fn: (...args: T) => R,
-  ...args: Partial<T>
+  ...args: TA
 ) => {
-  return (...rest: T) => fn(...([...args, ...rest] as T))
+  return (...rest: RemoveItemsInFront<T, TA>) =>
+    fn(...([...args, ...rest] as T))
 }
-
 /**
  * Like partial but for unary functions that accept
  * a single object argument
diff --git a/src/tests/curry.test.ts b/src/tests/curry.test.ts
index 8b7dc25d..e4a540fb 100644
--- a/src/tests/curry.test.ts
+++ b/src/tests/curry.test.ts
@@ -166,7 +166,8 @@ describe('curry module', () => {
     test('passes single args', () => {
       const add = (a: number, b: number) => a + b
       const expected = 20
-      const result = (_.partial(add, 10) as any)(10)
+      const partialed = _.partial(add, 10)
+      const result = partialed(10)
       assert.equal(result, expected)
     })
     test('passes many args', () => {