my_dsl = Alki::Dsl.build 'alki/dsls/dsl' do
  # Require other DSL. Value can also be a "load" string (see Alki::Loader section)
  require_dsl strings_dsl

  # This init block will be run *after* the strings_dsl one
  init do
    @transform = nil
  end

  dsl_method :transform do |&blk|
    # Don't need to share this, so instance variable works
    @transform = blk
  end

  # This finish block will be run *before* the strings_dsl one.
  finish do
    if @transform
      ctx[:strings].map! &@transform
    end
  end
end

my_dsl.build(separator: ', ') do
  transform(&:capitalize)

  add "hello"
  add "world"
end

# result => Hello, World