this patch allowed to use a proc to :label option, then we can pass a proc to ActiveAdmin `filter` method

formtastic_localizer_patch.rb

# ActiveAdmin use Formtastic as the "filter" field builder
# this patch allowed to use a proc to :label option, then we can pass a proc to `filter` method
# e.g.: filter :foo, :label => proc { I18n.tr('activerecord.attributes.foo.bar') }
module Formtastic
  class Localizer
    def localize_with_proc_value(key, value, type, options = {})
      if value.is_a?(::Proc)
        value.call(key)
      else
        localize_without_proc_value(key, value, type, options = {})
      end
    end

    alias_method_chain :localize, :proc_value
  end
end