1. A non-transitory computer-accessible memory medium storing program instructions, wherein the program instructions are executable by a computer system to: display a graphical program, wherein the graphical program comprises a first portion including a first plurality of interconnected nodes that visually indicates functionality of the first portion of the graphical program and operates according to a first computational model, and wherein the graphical program further comprises a second portion including a second plurality of interconnected nodes that visually indicates functionality of the second portion of the graphical program and operates according to a second computational model that is different than the first computational model, wherein the first portion of the graphical program includes a structure that has an interior region, wherein the second portion of the graphical program including the second plurality of interconnected nodes is displayed within the interior region of the structure; and generate a hardware description based on the graphical program, wherein the hardware description describes a hardware implementation of the graphical program, and wherein the hardware description is configured to configure a programmable hardware element to implement functionality of the graphical program.