Parmap is a minimalistic library allowing to exploit multicore
architecture for OCaml programs with minimal modifications: if you want
to use your many cores to accelerate an operation which happens to be a
map, fold or map/fold (map-reduce), just use Parmap's parmap, parfold
and parmapfold primitives in place of the standard List.map and friends,
and specify the number of subprocesses to use by the optional parameter
~ncores.