A partition_freely/4 predicate which partitions into arbitrarily many partitions by accepting a "partitioning closure" as first argument, returning the result as an SWI-Prolog dict where the dict's keys are the partition keys:

• partition_freely.pl
• partition_freely.plt

Example:

Define a partitioning predicate taking 3 arguments

partition_by_length_modulo_m(Modulo,Atom,Key) :-
   atom_length(Atom,Length),
   Key is Length mod Modulo.

A "partitioning closure" might then be for exmaple partition_by_length_modulo_m(5): a partially filled in predicate call.

Then:

?- partition_freely(
      partition_by_length_modulo_m(5),
      [silent,puffy,left,damaged,fascinated,deafening,
       wistful,whip,nest,inquisitive,imperfect,jog,unwieldy,provide,locket,reign],
      result_tag,
      DictOut).

DictOut = result_tag{
   0:[puffy, fascinated, reign],
   1:[silent, inquisitive, locket],
   2:[damaged, wistful, provide],
   3:[jog, unwieldy],
   4:[left, deafening, whip, nest, imperfect]}.