musicalEra.js

const musicalEraAliveIn = (startLife, endLife) => {
  const life         = range(startLife, endLife);
  const yearsAliveIn = compose(length, intersection(life));
  const largestBy    = compose(nth(0), reverse, sortBy);
  
  return largestBy(compose(yearsAliveIn, nth(1)), [
    ['Medieval',    range(476, 1400)],
    ['Renaissance', range(1400, 1600)],
    ['Baroque',     range(1600, 1760)],
    ['Classical',   range(1730, 1820)],
    ['Romantic',    range(1815, 1910)],
    ['Modern',      range(1900, 2100)]
  ])[0];
};

musicalEraAliveIn(1800, 1950); // => Romantic