moltres-utils/dist/data/nAry.js

Utils for Moltres apps

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = void 0;

var _curry = _interopRequireDefault(require("./curry"));

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }

/**
 * Wraps a function of any arity (including nullary) in a function that accepts exactly `n` parameters. Any extraneous parameters will not be passed to the supplied function.
 *
 * @func
 * @since v0.1.0
 * @category data
 * @sig Number -> (* -> a) -> (* -> a)
 * @param {Number} n The desired arity of the new function.
 * @param {Function} fn The function to wrap.
 * @returns {Function} A new function wrapping `fn`. The new function is guaranteed to be of
 *         arity `n`.
 * @example
 *
 *      const takesTwoArgs = (a, b) => [a, b]
 *
 *      takesTwoArgs.length //=> 2
 *      takesTwoArgs(1, 2) //=> [1, 2]
 *
 *      const takesOneArg = nAry(1, takesTwoArgs)
 *      takesOneArg.length //=> 1
 *      // Only `n` arguments are passed to the wrapped function
 *      takesOneArg(1, 2) //=> [1, undefined]
 */
const nAry = (0, _curry.default)((n, fn) => {
  let idx = 0;
  const argNames = [];

  while (idx < n) {
    argNames.push(`a${idx}`);
    idx += 1;
  }

  const func = new Function('fn', 'n', `return function(${argNames.join(', ')}) {
      return fn.apply(this, Array.prototype.slice.call(arguments, 0, n));
    }`);
  return func(fn, n);
});
var _default = nAry;
exports.default = _default;
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