This is achieved by adding constraints to type variables in parametrically polymorphic types. The ROC curve plots parametrically TPR(T) versus FPR(T) with T as the varying parameter. The structure features a parametrically designed atrium. An alternative to the above method is to define the PDF parametrically as formula 21. Many operations require some knowledge of the data types, but can otherwise work parametrically. Let "C" be given parametrically by ("x"("t"), "y"("t")). Parametrically, these clusters lie somewhere between a globular cluster and a dwarf spheroidal galaxy.