1. A non-transitory computer-accessible memory medium that stores program instructions executable by a computer system to perform: providing a graphical program development environment comprising a graphical specification and constraint language that allows specification of a model of computation and explicit declaration of constraints; creating a graphical program in a graphical specification and constraint language that allows specification of a model of computation and explicit declaration of constraints in response to user input, wherein the graphical program comprises: a specified model of computation; a plurality of interconnected functional blocks that visually indicate functionality of the graphical program; and graphically indicated specifications or constraints for at least one functional block of the functional blocks in the graphical program; wherein the specifications or constraints comprise: input count (IC), comprising a number of tokens consumed at an input terminal of the at least one functional block by one firing of the at least one functional block; output count (OC), comprising a number of tokens produced at an output terminal of the at least one functional block by one firing of the at least one functional block; execution time (ET), comprising a number of cycles needed by the functional block to complete firing; initiation interval (II), comprising a minimum number of cycles between firings of the functional block; input pattern (IP), comprising a sequence of Boolean values of length at most II, wherein the sequence of Boolean values aligns with the beginning of firing of the functional block, wherein each true value in the sequence denotes consumption of a token by the functional block; and output pattern (OP), comprising a sequence of Boolean values of length at most II, wherein the sequence of Boolean values aligns with the end of firing of the functional block, wherein each true value in the sequence denotes production of a token by the functional block; and analyzing the graphical program, including analyzing the specifications or constraints based on the specified model of computation; and automatically generating a timing accurate simulation of the graphical program.