4. A method in a computer system for generating executable code for a computer program, the method comprising the steps of: receiving an intentional program tree having nodes, each node representing a high-level computational construct of the computer program; for each node representing a high-level computational construct, transforming the node into an implementation of the high-level computational construct, the implementation represented by one or more nodes representing low-level computational constructs; and for each node representing a low-level computational construct, generating executable code that implements the low-level computational construct including the step of before the step of transforming, preprocessing nodes to store indications to control the transforming to identify errors.
5. The method of claim 4 wherein the indications include flags to indicate a low-level computational construct that corresponds to an overloaded high-level computational construct.