ember-car

ember-car is an ember-cli addon that provides Lisp-like car and cdr helpers.

The short version is that given a list (array), car returns the item at the head of the list (index 0), while cdr returns a list (array) without the first element.

Usage

Installation

ember install ember-car

In Your Application

Two template helpers are provided, called car and cdr. These are automatically resolved so you can just use them in your templates without any additional code.

These template helpers each take a single (positional) parameter, the list on which to operate. car returns a scalar value (or null, if the given array is empty); cdr returns an array (which may be empty).

Here's a brief partial example of their use:

// app/routes/index.js
import Ember from 'ember';

export default Ember.Route.extend({
  model() {
    return [ 'first', 'second', 'third' ];
  }
});

{{!-- app/templates/index.hbs --}}
car(model): {{car model}}
<br>
cdr(model): {{cdr model}}
<br>
car(cdr(model)): {{car (cdr model)}}

This example will render the output:

car(model): first
cdr(model): second,third
car(cdr(model)): second

Notes

These helpers are designed to be used with arrays, but also to not blow up when used with non-arrays (primitives or objects). If car is passed a non-array value, it simply returns it. If cdr is passed a non-array value, it returns an empty array. Effectively, non-array parameters are treated as if they were arrays that contained only the given value.

Why?!

This addon was created mainly as a jokey response to what feels to me like the increasing Lisp-ification of templates. You are welcome, however, to find actual uses for this.