Concurrent list operations.
These functions behave like the ones in the standard library's List module, except that multiple items can be processed concurrently.
They correspond to Lwt's Lwt_list.*_p operations. e.g. Lwt_list.iter_p becomes Fiber.List.iter. For the Lwt_list.*_s operations, just use the standard library function. e.g. Lwt_list.iter_s can be replaced by a plain List.iter.
filter f x is like List.filter f x except that the invocations of f are run concurrently in separate fibers.
map f x is like List.map f x except that the invocations of f are run concurrently in separate fibers.
filter_map f x is like List.filter_map f x except that the invocations of f are run concurrently in separate fibers.