1. A computer-implemented system for evaluating and executing a plurality of functional processes operating in a directed and acyclical manner, each of the plurality of functional processes receiving one or more data element inputs, the one or more data element inputs including a computed data element having a computed data element value generated by a generating functional process and a constant data element having a constant data element value, the system comprising: a function cache for storing data element values of the one or more data element inputs; signature generator means, coupled to said function cache, for generating a signature for each of the data element values, wherein said signature is a function of a selected aspect of the generating functional process and signatures of the data element inputs received by the generating functional process, said signature indicating a location of the data element value in said function cache; function evaluator means, coupled to said signature generator means and said function cache, for recursively evaluating uncomputed dam elements in a depth-first manner, and for retrieving a previously computed dam element value associated with said uncomputed data element from said function cache when a signature of said previously computed data element value is identical to a signature of said uncomputed data element value; and functional executor means, coupled to said function evaluator means, for executing the generating functional process when said previously computed data element value associated with said data element does not exist in said function cache.