Merge pull request #26 from giraugh/feat/intersperse-array

`intersperseArray` utility

.changeset/good-terms-deliver.md

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+---
+"@giraugh/tools": minor
+---
+
+Implement intersperseArray utility

lib/arrays/intersperseArray.ts

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+/**
+ * Intersperse a seperator element between every element of a given array
+ * @param arr the array to intersperse into
+ * @param sep a seperator element to distribute throughout `arr`
+ * @returns `arr` with `sep` interspersed between every pair of elements
+ *
+ * @example
+ * intersperseArray([[1, 2], [3, 4], [5, 6]], []) // [[1, 2], [], [3, 4], [], [5, 6]]
+
+ * @example
+ * intersperseArray(['alpha', 'beta', 'gamma'], '!') // ['alpha', '!', 'beta', '!', 'gamma']
+ */
+export const intersperseArray = <T>(arr: T[], sep: T): T[] => {
+  const gen = function*() {
+    while (arr.length > 0) {
+      yield arr.shift()!
+      if (arr.length > 0) yield sep
+    }
+  }
+  return Array.from(gen())
+}
+
+
+if (import.meta.vitest) {
+  const { expect, it } = import.meta.vitest
+
+  it('works for example 1', () => {
+    const inter = intersperseArray([[1, 2, 3], [4, 5, 6], [7, 8, 9]], [])
+    expect(inter).toEqual([[1, 2, 3], [], [4, 5, 6], [], [7, 8, 9]])
+  })
+
+  it('works for example 2', () => {
+    const inter = intersperseArray(['alpha', 'beta', 'gamma'], '!')
+    expect(inter).toEqual(['alpha', '!', 'beta', '!', 'gamma'])
+  })
+
+  it('does nothing to an empty array', () => {
+    expect(intersperseArray([] as string[], 'hello')).toEqual([])
+  })
+
+  it('does nothing to an array with one element', () => {
+    expect(intersperseArray(['suave'], '$')).toEqual(['suave'])
+  })
+}