zip

Combine matching entries from maps.

Similar: cartesianProduct, zip.

function zip(xs, fm, fe, vd?)
// xs: maps
// fm: map function (vs, k)
// fe: end function (dones) [array.some]
// vd: default value

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

var x = new Map([['a', 1], ['b', 2], ['c', 3]]);
var y = new Map([['a', 10], ['b', 20]]);
map.zip([x, y]);
// → Map(2) { 'a' => [ 1, 10 ], 'b' => [ 2, 20 ] } (shortest)

map.zip([x, y], ([a, b]) => a + b);
// → Map(2) { 'a' => 11, 'b' => 22 }

map.zip([x, y], null, array.some);
// → Map(2) { 'a' => [ 1, 10 ], 'b' => [ 2, 20 ] } (shortest)

map.zip([x, y], null, array.every, 0);
// → Map(3) { 'a' => [ 1, 10 ], 'b' => [ 2, 20 ], 'c' => [ 3, 0 ] } (longest)

References

• Data.List.zipWith: Haskell
• List-Extra.zip: elm
• zip: Python
• itertools.zip_longest: Python
• zip: Ruby
• _.zip: lodash
• _.zipWith: lodash
• Array.zip: sugarjs