What is Utilrb ? Utilrb is yet another Ruby toolkit, in the spirit of facets. It includes all the standard class extensions I use in my own projects like Genom.rb. == Utilrb's C extension Utilrb includes a C extension in ext/. It is optional, but some of the functionalities will be disabled if it is not present. Trying to require a file in which there is a C-only feature will yield a warning on STDOUT. * some features have a Ruby version, but a C version is provided for performance: - Enumerable#each_uniq * some features are C-only - ValueSet class - Kernel#swap!