Clay supports basic array operations.

You can declare an array:

var empty = [] // no elements
var cities = [ "Milan", "London", "Cairo" ]

You can add elements to an array:

cities = cities + "New York" // append one element
cities = cities + ["Rome", "Berlin"] // appen more elements at once
cities = ["Madrid", "Paris"] + cities // prepend elements 

You can check if an element is found in an array:

var city = "London"
if (city in cities) {
	// do something
}

You can loop through the elements of an array:

for (x : cities) {
	// x contains the nth element
}