This paper introduces a JAVA based library for parametric modelling through programming. From the recent advent of scripting tools integrated into commercial CAAD software and everyday design practice, the use of programming applied to an architectural design process becomes a necessary field of study. The ANAR+ library is a parametric geometry environment meant to be used as programming interface by designers. Form exploration strategies based on parametric variations depends on the internal logic description, a key role for form generation. In most commercial CAD software, geometric data structures are often predefined objects, thus constraining the form exploration, whereas digital architectural research and teaching are in need for an encompassing tool able to step beyond new software products limitations. We introduce key concepts of the library and show a use of the library within a form finding process driven by irradiance simulation.