Documentation for method first-date-in-month assembled from the following pages:

Class: Date §

From Date

(Date) method first-date-in-month §

Defined as:

method first-date-in-month(Date:D: --> Date:D)

Returns the first date in the month of the Date object. Otherwise, returns the invocant if the day value is already the first day of the month.

say Date.new('2015-11-24').first-date-in-month; # OUTPUT: «2015-11-01␤»