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; you can specify the number of
subprocesses to use with the optional parameter ncores, and the
size of granularity of the parallel computation with the optional
parameter chunksize.