feat: let counting accept any iterable

+71 bytes

src/array/counting.ts

@@ -1,3 +1,5 @@
+import { toIterable, type ToIterableItem } from 'radashi'
+
 /**
  * Counts the occurrences of each unique value returned by the `identity`
  * function when applied to each item in the array.
@@ -7,19 +9,17 @@
  * // { even: 2, odd: 2 }
  * ```
  */
-export function counting<T, TId extends string | number | symbol>(
-  array: readonly T[],
-  identity: (item: T) => TId,
-): Record<TId, number> {
-  if (!array) {
-    return {} as Record<TId, number>
+export function counting<T extends object, K extends keyof any>(
+  iterable: T,
+  identity: (item: ToIterableItem<T>) => K,
+): Record<K, number> {
+  if (!iterable) {
+    return {} as Record<K, number>
   }
-  return array.reduce(
-    (acc, item) => {
-      const id = identity(item)
-      acc[id] = (acc[id] ?? 0) + 1
-      return acc
-    },
-    {} as Record<TId, number>,
-  )
+  const counts = {} as Record<K, number>
+  for (const item of toIterable(iterable)) {
+    const id = identity(item)
+    counts[id] = (counts[id] ?? 0) + 1
+  }
+  return counts
 }