How to convert custom date to type date/time

We are using a list of links to webpages in the site we are just building. The list is compiled from a number of files in data/sites/ that look like this:

name = "some name"
url = ""
date = "2015-12-31T23:59:50+02:00"

We would like to use the date field to limit the list to links that have a date not older than - let’s say - six weeks ago. Unfortunately the date field is of type String and thus cannot be converted to a time stamp that could be compared with .Now.Unix.

So my question is: how would we proceed to achieve what we want? Is there a way to do that?

There have been similar questions but I did not find the answer in any of the posts …

Thanks in advance!

Remove the quotes and use proper dates in your data files.