union$

Gives union of first array with another.

array.union$(x, y, [fn]);
// x:  an array (updated)
// y:  another array
// fn: compare function (a, b)

const array = require('extra-array');

array.unfoldr(v => v===0? undefined : [v, v-1], 10);
// [ 10, 9, 8, 7, 6, 5, 4, 3, 2, 1 ]

references

• Data.List.unfoldr: Haskell