classnames package in four lines with Ramda

fn-classnames.js

import { when, is, map, filter, compose, nth, flatten, pipe, join } from 'ramda';
const isValueTruthy = compose(Boolean, nth(1));
const getTruthyKeys = compose(map(nth(0)), filter(isValueTruthy), Object.entries);
const classnames = (...args) => pipe(flatten, filter(Boolean), map(when(is(Object), getTruthyKeys)), flatten, join(' '))(args);

console.log(classnames('foo', 'bar', ['baz', ['deep', [[{ nested: true , falseNested: false }]]]], '', false, { foobar: true, no: false }));