Add functionality related to boolean type

- add `isBoolean` / `ensureBoolean` function
- add ability for `isLike` to compare objects with boolean types

Author: monaqa

ensure.ts

@@ -1,5 +1,6 @@
 import {
   isArray,
+  isBoolean,
   isFunction,
   isLike,
   isNone,
@@ -50,6 +51,13 @@ export function ensureNumber(x: unknown): asserts x is number {
   return ensure(x, isNumber, "The value must be number");
 }
 
+/**
+ * Ensure if `x` is boolean by raising an `EnsureError` when it's not.
+ */
+export function ensureBoolean(x: unknown): asserts x is boolean {
+  return ensure(x, isBoolean, "The value must be boolean");
+}
+
 /**
  * Ensure if `x` is array by raising an `EnsureError` when it's not.
  */

is.ts

@@ -14,6 +14,13 @@ export function isNumber(x: unknown): x is number {
   return typeof x === "number";
 }
 
+/**
+ * Return true if the value is boolean
+ */
+export function isBoolean(x: unknown): x is boolean {
+  return typeof x === "boolean";
+}
+
 /**
  * Return true if the value is array
  */
@@ -81,6 +88,9 @@ export function isLike<R, T extends unknown>(
   if (isNumber(ref) && isNumber(x)) {
     return true;
   }
+  if (isBoolean(ref) && isBoolean(x)) {
+    return true;
+  }
   if (isArray(ref, pred) && isArray(x, pred)) {
     return ref.length === 0 || (
       ref.length === x.length &&