nAry.js

import _curry2 from './internal/_curry2';


/**
 * 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
 * @memberOf R
 * @since v0.1.0
 * @category Function
 * @sig Number -> (* -> a) -> (* -> a)
 * @param {Number} n The desired arity of the new function.
 * @param {Function} fn The function to wrap.
 * @return {Function} A new function wrapping `fn`. The new function is guaranteed to be of
 *         arity `n`.
 * @see R.binary, R.unary
 * @example
 *
 *      const takesTwoArgs = (a, b) => [a, b];
 *
 *      takesTwoArgs.length; //=> 2
 *      takesTwoArgs(1, 2); //=> [1, 2]
 *
 *      const takesOneArg = R.nAry(1, takesTwoArgs);
 *      takesOneArg.length; //=> 1
 *      // Only `n` arguments are passed to the wrapped function
 *      takesOneArg(1, 2); //=> [1, undefined]
 * @symb R.nAry(0, f)(a, b) = f()
 * @symb R.nAry(1, f)(a, b) = f(a)
 * @symb R.nAry(2, f)(a, b) = f(a, b)
 */
var nAry = _curry2(function nAry(n, fn) {
  switch (n) {
    case 0: return function() {return fn.call(this);};
    case 1: return function(a0) {return fn.call(this, a0);};
    case 2: return function(a0, a1) {return fn.call(this, a0, a1);};
    case 3: return function(a0, a1, a2) {return fn.call(this, a0, a1, a2);};
    case 4: return function(a0, a1, a2, a3) {return fn.call(this, a0, a1, a2, a3);};
    case 5: return function(a0, a1, a2, a3, a4) {return fn.call(this, a0, a1, a2, a3, a4);};
    case 6: return function(a0, a1, a2, a3, a4, a5) {return fn.call(this, a0, a1, a2, a3, a4, a5);};
    case 7: return function(a0, a1, a2, a3, a4, a5, a6) {return fn.call(this, a0, a1, a2, a3, a4, a5, a6);};
    case 8: return function(a0, a1, a2, a3, a4, a5, a6, a7) {return fn.call(this, a0, a1, a2, a3, a4, a5, a6, a7);};
    case 9: return function(a0, a1, a2, a3, a4, a5, a6, a7, a8) {return fn.call(this, a0, a1, a2, a3, a4, a5, a6, a7, a8);};
    case 10: return function(a0, a1, a2, a3, a4, a5, a6, a7, a8, a9) {return fn.call(this, a0, a1, a2, a3, a4, a5, a6, a7, a8, a9);};
    default: throw new Error('First argument to nAry must be a non-negative integer no greater than ten');
  }
});
export default nAry;