module Rack module Reducer # refine Proc and hash in this scope only module Refinements refine Proc do def required_argument_names parameters.select { |type, _| type == :keyreq }.map(&:last) end def all_argument_names parameters.map(&:last) end def satisfies?(params) keywords = required_argument_names params.slice(*keywords).keys.to_set == keywords.to_set end end # backport Hash#slice for older rubies unless {}.respond_to?(:slice) refine Hash do def slice(*keys) [keys, values_at(*keys)].transpose.select { |_k, val| val }.to_h end end end end end end