getFirstThreeFromArray using Ramda

getFirstThreeFromArray

// const { compose, defaultTo, equals, map, slice } = R;
const slice2DArray = (slice) => compose(defaultTo([]), map(slice));
const getFirstThreeFromArray = slice2DArray(slice(0, 3));

const input_data = [
  ["a", "b", "c", "d"],
  ["a", "b", "c", "d"],
  ["a", "b", "c", "d"],
  ["a", "b"],
  ["x", "y", "z", "z1"],
  [],
];
const output_data = [
  ["a", "b", "c"],
  ["a", "b", "c"],
  ["a", "b", "c"],
  ["a", "b"],
  ["x", "y", "z"],
  [],
];
// test
equals(getFirstThreeFromArray(input_data), output_data);