Basic functions for object & function manipulation

[Pisces] / function.js

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+// ♓🌟 Piscēs ∷ function.js
+// ====================================================================
+//
+// Copyright © 2022 Lady [@ Lady’s Computer].
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at <https://mozilla.org/MPL/2.0/>.
+
+import { defineOwnProperty, isObject } from "./object.js";
+
+/**
+ * Creates a bound function from the provided function using the
+ * provided this value and arguments list.
+ *
+ * ☡ As with call and construct, the arguments must be passed as an
+ * array.
+ */
+export const bind = (() => {
+  const callBind = Function.prototype.call.bind(
+    Function.prototype.bind,
+  );
+  const bind = ($, boundThis, boundArgs) =>
+    callBind($, boundThis, ...boundArgs);
+  return bind;
+})();
+
+/**
+ * Calls the provided function with the provided this value and
+ * arguments list.
+ *
+ * ☡ This is an alias for Reflect.apply—the arguments must be passed
+ * as an array.
+ */
+export const call = Reflect.apply;
+
+/**
+ * Constructs the provided function with the provided arguments list
+ * and new target.
+ *
+ * ☡ This is an alias for Reflect.construct—the arguments must be
+ * passed as an array.
+ */
+export const construct = Reflect.construct;
+
+/** Returns whether the provided value is a constructor. */
+export const isConstructor = ($) => {
+  if (!isObject($)) {
+    // The provided value is not an object.
+    return false;
+  } else {
+    // The provided value is an object.
+    try {
+      construct(
+        function () {},
+        [],
+        $,
+      ); // will throw if $ is not a constructor
+      return true;
+    } catch {
+      return false;
+    }
+  }
+};
+
+/**
+ * Returns a new function which calls the provided function with its
+ * first argument as the `this` value and the remaining arguments
+ * passed through.
+ *
+ * ※ This is effectively an alias for Function.prototype.call.bind.
+ */
+export const makeCallable = (() => {
+       const functionCall = Function.prototype.call;
+       const callable = ($) => defineOwnProperty(
+               bind(functionCall, $, []),
+               "length",
+               { value: $.length + 1 },
+       );
+       return callable;
+})();
+
+/**
+ * Returns whether the provided object inherits from the prototype of
+ * the provided function.
+ */
+export const ordinaryHasInstance = makeCallable(
+       Function.prototype[Symbol.hasInstance],
+);