Perl modules Generate permutations, combinations and subsets, returning them as a list The same but the results are returned via a callback routine so large numbers of results can be handled A class for programming board games HashIO can save the contents of almost any hash in a text file. The file can be read again to restore the hash.
The fileformat is straight forward so files can be made by hand (configuration files etc.) A simple class for computations with calendar dates in the range 1/3/1900 - 28/2/2100. For puzzles with prime numbers Conversion of color values in RGB-format to and from HSV-format Search a file in a number of directories (cf. PATH).

All modules contain POD documentation in English (or a language which resembles English).