Description:

The map function applies a user supplied transformation function to
each element in a list, returning a new list containing the
transformed elements.

This module provides a 'parallel map'. Multiple worker processes are
forked so that many instances of the transformation function may be
executed simultaneously.

For time consuming operations, particularly operations that spend most
of their time waiting for I/O, this is a big performance win. It also
provides a simple idiom to make effective use of multi CPU systems.

There is, however, a considerable overhead associated with forking, so
the example in the synopsis (doubling a list of numbers) is not a
sensible use of this module.