lets_get_closure_juices_flowing.rb

# Just copy in TextMate and play
#
class Chain
  def initialize lambdas
    @lambdas = lambdas
  end
  
  # Wrapper.
  #
  def self.[] lam, *args
    new args.map { |arg| lam[*arg] }
  end
  
  # Non-executing proc join.
  #
  def join prok
    proks = [prok]*(@lambdas.size-1)
    proks = @lambdas.zip(proks).flatten.compact
    lambda { proks.each(&:call) }
  end
  
  # Executing proc join.
  #
  def join! prok
    join(prok).call
  end
  
  def call *args
    join(nil).call *args
  end
end

module Kernel
  def chained lambdas
    Chain.new lambdas
  end
end

restart = lambda { |i| lambda { puts "Restarting Server #{i}." } }
wait    = lambda { puts "Waiting"; sleep 0.1 }

Chain[restart, 1, 2, 3].join! wait
# or
restarts = [1,2,3].map { |i| restart[i] }
chained(restarts).join! wait
# or funkier! :)
chain = chained(restarts)
chained([chain.join(chain), chain.join(wait)]).join! wait