To run the benchmarks (MacOS):
brew install icu4c
bundle config build.uri_parser -- "--with-cppflags=-I/usr/local/opt/icu4c/include" "--with-ldflags=-L/usr/local/opt/icu4c/lib" "--with-cxxflags=-std=c++11"
(no need to use brew link; it won't work anyway...)
bundle
bundle exec ruby bench.rb