How to apply case-when on lambdas

weekday.rb

#!/usr/bin/env ruby

class Proc
	def ===(*parameters)
		self.call(*parameters)
	end
end

sunday    = Proc.new { |time| time.wday == 0 }
monday    = Proc.new { |time| time.wday == 1 }
tuesday   = Proc.new { |time| time.wday == 2 }
wednesday = Proc.new { |time| time.wday == 3 }
thursday  = Proc.new { |time| time.wday == 4 }
friday    = Proc.new { |time| time.wday == 5 }
saturday  = Proc.new { |time| time.wday == 6 }

case Time.now
	when sunday
		puts "Faulenzen!"
	when monday, tuesday
		puts "Örks, arbeiten. :-("
	when wednesday
		puts "Hälfte geschafft."
	when thursday
		puts "Ein Tag noch!"
	when friday
		puts "Juhu, bald Wochenende!"
	when saturday
		puts "Partytime!"
end