gistfile1.rb

irb(main):001:0> # Builds a function which returns true
irb(main):002:0* # whenever _every_ function in 'predicates'
irb(main):003:0* # returns true.
irb(main):004:0* def conjoin *predicates
irb(main):005:1>   base = lambda {|*args| true }
irb(main):006:1>   predicates.inject(base) do |built, pred|
irb(main):007:2*     lambda do |*args|
irb(main):008:3*       built.call(*args) && pred.call(*args)
irb(main):009:3>     end
irb(main):010:2>   end
irb(main):011:1> end
=> nil
irb(main):012:0> is_awesome_number = conjoin(lambda {|x| x > 10}, lambda {|x| x % 2 == 0})
=> #<Proc:0x001690cc@(irb):7>
irb(main):013:0> is_awesome_number.call(22)
=> true
irb(main):014:0> is_awesome_number.call(23)
=> false
irb(main):015:0> is_awesome_number.call(8)
=> false