FP util functions

utils.js

const sequence = () => compose.apply(this, Array.prototype.slice.call(arguments).reverse());

const pipe = (...fns) => x => fns.reduce((y, f) => f(y), x);

const compose = (fn, ...rest) =>
(!rest.length && Boolean(fn)) ?
    fn :
    (prop, ...args) =>
        fn(compose(...rest)(prop, ...args), ...args);

function curry (fn) {
    var args = Array.prototype.slice.call(arguments, 1);
    return function () {
        return fn.apply(this, args.concat(Array.prototype.slice.call(arguments, 0)));
    }
}

var inc = curry((a, b) => a + b, 1, 2);

inc(6);

const curry = fn => (...args) => {
    if (args.length < fn.length) {
        return (...restArgs) => curry(fn)(...args, ...restArgs);
    }
    return fn.apply(this, args);
};