import { curry, head, slice, reduce, curryN, map } from 'ramda';
import ap from './internal/ap';
/**
* "lifts" a function to be the specified arity, so that it may "map over" objects that satisfy
* the fantasy land Apply spec of algebraic structures.
*
* Lifting is specific for {@link https://github.com/scalaz/scalaz|scalaz} and {@link http://www.functionaljava.org/|functional java} implementations.
* Old version of fantasy land spec were not compatible with this approach,
* but as of fantasy land 1.0.0 Apply spec also adopted this approach.
*
* This function acts as interop for ramda <= 0.23.0 and {@link https://monet.github.io/monet.js/|monet.js}.
*
* More info {@link https://github.com/fantasyland/fantasy-land/issues/50|here}.
*
* @func liftFN
* @memberOf RA
* @since {@link https://char0n.github.io/ramda-adjunct/1.2.0|v1.2.0}
* @category Function
* @sig Apply a => Number -> (a... -> a) -> (a... -> a)
* @param {Number} arity The arity of the lifter function
* @param {Function} fn The function to lift into higher context
* @return {Function} The lifted function
* @see {@link http://ramdajs.com/docs/#lift|lift}, {@link http://ramdajs.com/docs/#ap|ap}
* @example
*
* const { Maybe } = require('monet');
*
* const add3 = (a, b, c) => a + b + c;
* const madd3 = RA.liftFN(3, add3);
*
* madd3(Maybe.Some(10), Maybe.Some(15), Maybe.Some(17)); //=> Maybe.Some(42)
* madd3(Maybe.Some(10), Maybe.Nothing(), Maybe.Some(17)); //=> Maybe.Nothing()
*/
const liftFN = curry((arity, fn) => {
const lifted = curryN(arity, fn);
return curryN(arity, (...args) => {
const accumulator = map(lifted, head(args));
const apps = slice(1, Infinity, args);
return reduce(ap, accumulator, apps);
});
});
export default liftFN;