code4

f.rb

include FactChecker

define_fact :festivals,                             :if => lambda{|o| o.festivals > 0}
define_fact :scenario,                              :if => :scenario?
define_fact :requiest   => [:festivals, :scenario], :if => :equipment?
define_fact :members    => :request,                :if => lambda{|o| o.members > 0}
define_fact :basic_info => :request,                :if => lambda{|o| o.name.present? && o.description.present?}
define_fact :submit     => [:members, :basic_info], :if => :submitted?

Do you think this can be used as a short-cut alternative for positive predicate?
def_fact :f1 => :f2 do |f|
f.festivals > 0
end