There's a new combinator: bcompare :: [Benchmark] -> Benchmark
The first 'bench' in the list is the reference benchmark.
All other benchmarks are compared against that reference.
The user can specify to write the comparisons to a CSV file
using the -r (or --compare) command line flag.
The CSV file uses the following format:
Reference,Name,% faster than the reference
where the % is currently printed without precision (%.0f).