In the beginning, mathematicians wrote programs to do things. Usually in FORTRAN, sometimes in other languages. Then along came statistical packages. They did many common things and saved a lot of work.
Many researchers were developing new techniques though, and wanted to be able to use the standard facilities of a statistical package but integrated with their new methods. The new generation of statistical software enabled this to be done.
The package Splus has a facility for creating libraries of new functions, easily accessible to the users. Splancs is a library of functions for point pattern analysis.
A postscript file documenting Splancs Functions is available, as well as a technical report and a report on new functions released in Splancs version 2.