How can we use collections in lightning in salesforce?

<aura:attribute name="numbers" type="List"/>
<lightning:button onclick="{!c.getNumbers}" label="Display Numbers" />
<aura:iteration var="num" items="{!v.numbers}">
{!num.value}
</aura:iteration>

/** Client-side Controller **/
({
getNumbers: function(component, event, helper) {
var numbers = [];
for (var i = 0; i < 20; i++) {
numbers.push({
value: i
});
}
component.set("v.numbers", numbers);
}
})