_result

$ php bootstrap/api.php get "/periods/3" 
200 OK
content-type: application/hal+json

{
    "periods": [
        {
            "date": {
                "date": "2015-06-08 23:27:51.000000",
                "timezone_type": 3,
                "timezone": "Asia/Tokyo"
            },
            "year": "2015",
            "month": "06",
            "day": "08",
            "_links": {
                "self": {
                    "href": "/date/2015/06/08"
                }
            }
        },
        {
            "date": {
                "date": "2015-06-09 23:27:51.000000",
                "timezone_type": 3,
                "timezone": "Asia/Tokyo"
            },
            "year": "2015",
            "month": "06",
            "day": "09",
            "_links": {
                "self": {
                    "href": "/date/2015/06/09"
                }
            }
        },
        {
            "date": {
                "date": "2015-06-10 23:27:51.000000",
                "timezone_type": 3,
                "timezone": "Asia/Tokyo"
            },
            "year": "2015",
            "month": "06",
            "day": "10",
            "_links": {
                "self": {
                    "href": "/date/2015/06/10"
                }
            }
        },
        {
            "date": {
                "date": "2015-06-11 23:27:51.000000",
                "timezone_type": 3,
                "timezone": "Asia/Tokyo"
            },
            "year": "2015",
            "month": "06",
            "day": "11",
            "_links": {
                "self": {
                    "href": "/date/2015/06/11"
                }
            }
        },
        {
            "date": {
                "date": "2015-06-12 23:27:51.000000",
                "timezone_type": 3,
                "timezone": "Asia/Tokyo"
            },
            "year": "2015",
            "month": "06",
            "day": "12",
            "_links": {
                "self": {
                    "href": "/date/2015/06/12"
                }
            }
        }
    ],
    "to": "3",
    "_links": {
        "self": {
            "href": "/periods/3"
        }
    }
}

PeriodCollection.php

<?php

namespace Embed\Sample\Resource\App;

use Bear\Resource\ResourceObject;
use Bear\Resource\FactoryInterface;
use Bear\Resource\AbstractUri;

class PeriodCollection extends ResourceObject {
	/**
	 * @var FactoryInterface
	 */
	private $resourceFactory;

	public function __construct(FactoryInterface $f) {
		$this->resourceFactory = $f;
	}

	public function onGet($to) {
		$this["periods"] = array_map(
			function ($n) use($to) {
				return new \DateTime("+$n day");
			},
			range(0, $to+1)
		);

		$fn = function (\DateTime $content) {
			return [
				'year' => $content->format('Y'),
				'month' => $content->format('m'),
				'day' => $content->format('d'),
			];
		};
		$this->body = $this->toItemResource('date', '/periodItem', $this->body, $fn);

		return $this;
	}

	private function toItemResource($rel, $path, $contents, callable $fn) {
		$uri = clone $this->uri;
		$uri->path = $path;

		return array_map(
			function ($content) use($rel, $uri, $contents, $fn) {
				return is_array($content) ? $this->toItemResourceSub($rel, $uri, $content, $fn) : $content;
			},
			$contents
		);

	}

	private function toItemResourceSub($rel, $uri, array $content, callable $keySelector) {
		return array_map(
			function ($body) use($rel, $uri, $keySelector) {
				$ro = $this->resourceFactory->newInstance($uri);
				$ro[$rel] = $body;
				$ro->uri = clone $uri;
				$ro->uri->query = $keySelector($body);

				return $ro;
			},
			$content
		);
	}

	public function __toString() {
		$this->body = array_map(
			function ($resources) {
				return $this->renderChildren($resources);
			},
			$this->body
		);

		return parent::__toString();
	}

	protected function renderChildren($resources) {
		if (! (current($resources) instanceof ResourceObject)) return $resources;

		return array_map(
			function (ResourceObject $ro) {
				return json_decode((string)$ro);
			},
			$resources
		);
	}
}

PeriodItem.php

<?php

namespace Embed\Sample\Resource\App;

use Bear\Resource\ResourceObject;

class PeriodItem extends ResourceObject {
	public function onGet($year, $month, $day) {
		$this["date"] = new \DateTime("{$year}-{$month}-{$day}");

		return $this;
	}
}