Text.to_date

If this Text object’s value is in either of the following formats: YYYY-MM-DD HH:MM or YYYY-MM-DD then returns a new DateTime object instantiated to that date and time. If this Text object is not in one of these two formats it returns Nothing.

var t = "2017-12-25 23:00"
var d = t.to_date
d.day_name # Monday.