✨ feat(array-methods): add Array.Reverse and Array.Shift methods

changelog/next.md

@@ -48,6 +48,12 @@
 + Add a new method of `Array` namespace:
   + `Array.LastIndexOf<Arr, T>`
 
+### 2025-07--09 (feature/array-methods → main)
+
++ Add two new methods of `Array` namespace:
+  + `Array.Reverse<Arr>`
+  + `Array.Shift<Arr, Mode>`
+
 ## ⚡ Improvements
 
 ## 🐦‍🔥 No longer broken

lib/Array/index.d.ts

@@ -25,7 +25,7 @@ declare namespace Array {
 export type CreateArrayFromLength<
   L extends number, 
   T extends unknown = undefined, 
-  Count extends T[] = []
+  Count extends unknown[] = []
 > = Integer.IsNegative<L> extends true
   ? []
   : Count["length"] extends L
@@ -53,7 +53,7 @@ export type CreateArrayFromLength<
 export type At<
   Arr extends unknown[],
   N extends number, 
-  Count extends unknown[] = []
+  Count extends 0[] = []
 > = Integer.Eq<Arr["length"], 0> extends true
   ? never
   : Integer.IsNegative<N> extends true
@@ -65,7 +65,7 @@ export type At<
         ? F
         : never
       : Arr extends [infer F, ...infer Rest]
-        ? At<Rest, N, [...Count, F]>
+        ? At<Rest, N, [...Count, 0]>
         : never;
 
 /**
@@ -357,6 +357,60 @@ export type Pop<
  */
 export type Push<Arr extends unknown[], E extends unknown> = [...Arr, E];
 
+/**
+ * This method is like `Array.prototype.reverse`, it reverses the array.
+ * 
+ * @param Arr The array to be reversed.
+ * @param Result The array to store the final reversed result in the process
+ * procedure.
+ * @returns The reversed array.
+ * 
+ * @example
+ * type Reverse1 = Array.Reverse<[1, 2, 3]>;  // [3, 2, 1]
+ * type Reverse2 = Array.Reverse<[]>;         // []
+ */
+export type Reverse<Arr extends unknown[], Result extends unknown[] = []>
+  = Arr extends [infer F, ...infer Rest]
+    ? Reverse<Rest, [F, ...Result]>
+    : Result;
+
+/**
+ * This method is like `Array.prototype.shift`, but it cannot change the array itself
+ * (types are not references). So we can use `Mode` to determine whether this method
+ * returns the rest part or returns the shifted element.
+ * 
+ * @param Arr The array to be shifted.
+ * @param Mode If you choose mode `"get-rest"`, this method will return the rest
+ * part of array. If you choose mode `"get-shift-element"`, this method will return the
+ * shifted element. Default to `"get-rest"`
+ * @returns When `Mode` is `"get-rest"`, returns the rest part. When `Mode` is `"get-
+ * shift-element"`, returns the shifted element.
+ * 
+ * @example
+ * // "get-rest" mode
+ * type Shift1 = Array.Shift<[1, 2, 3]>;        // [2, 3]
+ * type Shift2 = Array.Shift<[1], "get-rest">;  // []
+ * type Shift3 = Array.Shift<[], "get-rest">;   // never
+ * 
+ * // "get-shift-element" mode
+ * type Shift4 = Array.Shift<[1, 2, 3], "get-shift-element">; // 1
+ * type Shift5 = Array.Shift<[1], "get-shift-element">;       // 1
+ * type Shift6 = Array.Shift<[], "get-shift-element">;        // never
+ */
+export type Shift<
+  Arr extends unknown[],
+  Mode extends 
+    | "get-rest"
+    | "get-shift-element"
+    = "get-rest"
+> = Mode extends "get-rest" 
+  ? Arr extends [infer ShiftElement, ...infer Rest]
+    ? Rest
+    : never
+  : Arr extends [infer ShiftElement, ...infer Rest]
+    ? ShiftElement
+    : never;
+
 }
 
 export default Array;

test/lib-Boolean.test.ts

@@ -25,6 +25,10 @@ type CaseLibBoolean = [
   Expect<Equal<Boolean.And<true, false>, false>>,
   Expect<Equal<Boolean.And<true, true>, true>>,
 
+  // Boolean.Not
+  Expect<Equal<Boolean.Not<false>, true>>,
+  Expect<Equal<Boolean.Not<true>, false>>,
+
   // Boolean.Nor
   Expect<Equal<Boolean.Nor<false, false>, true>>,
   Expect<Equal<Boolean.Nor<false, true>, false>>,

test/script/lib-gen.sh

@@ -54,7 +54,7 @@ declare -A test_cases=(
 
   ["Boolean.And"]="false‖false∷false false‖true∷false true‖false∷false true‖true∷true"
   ["Boolean.Or"]="false‖false∷false false‖true∷true true‖false∷true true‖true∷true"
-  ["Boolean.Nor"]="false∷true true∷false"
+  ["Boolean.Not"]="false∷true true∷false"
   ["Boolean.Nand"]="false‖false∷true false‖true∷true true‖false∷true true‖true∷false"
   ["Boolean.Nor"]="false‖false∷true false‖true∷false true‖false∷false true‖true∷false"
   ["Boolean.MultipleAnd"]="[true,true,true]∷true [true,false,true]∷false [false,false,false]∷false"