Yaml and Markdown yaml front matter doesn't like single digit months or days

[Tyriar]

According to the YAML spec http://yaml.org/type/timestamp.html, single digits are allowed:

-[0-9][0-9]? # (month)
-[0-9][0-9]? # (day)

Note this applies to both the front matter section at the top of a markdown file (as below) and in a .yml file

Test text:

---
date1 : 2016-8-2
date1 : 2016-8-20
date1 : 2016-08-2
date1 : 2016-08-20
date2 : 2016-11-20
---

[mjbvz]

I think this is by design. The yaml timestamp spec is weird in this case. Iit looks like single digit months and years are only supported in full timestemp literals that include times:

 [0-9][0-9][0-9][0-9]-[0-9][0-9]-[0-9][0-9] # (ymd)
|[0-9][0-9][0-9][0-9] # (year)
 -[0-9][0-9]? # (month)
 -[0-9][0-9]? # (day)
 ([Tt]|[ \t]+)[0-9][0-9]? # (hour)
 :[0-9][0-9] # (minute)
 :[0-9][0-9] # (second)
 (\.[0-9]*)? # (fraction)
 (([ \t]*)Z|[-+][0-9][0-9]?(:[0-9][0-9])?)? # (time zone)

In the first ymd option, you have to use two digits for months and days. I've checked a few yaml validators and they seem to be consistent in parsing 2016-8-2 as a string instead of as a date

[Tyriar]

Ah you're right, I didn't look thoroughly enough and thought the opening paren on the hour line ended at the end. 👍

I guess I'll just use double digits then 😉