1. A structured data processing system, comprising: a processor; system memory; an inferring component that infers an operation from a plurality of available operations to be performed on a data structure from contextual information about the data structure, wherein the plurality of operations use different portions of data during execution of the data depending on which operation is performed, and wherein the contextual information includes one or more previous runs and execution behavior; an analyzer component that analyzes the inferred operation to determine which portion of data the inferred operation is to use and is to be materialized into memory; a constructor component that constructs a data representation that is separate from and external to the data that is to be materialized, according to the analyzer component's determination of which data is to be materialized into memory, wherein the data representation describes computations of the data structures that are to be materialized rather than comprising the structures in their original format or in another format, such that a declarable set of data structures is identifiable and accessible using the data representation; an evaluation component that evaluates the declarable set of data structures represented by the data representation in accordance with the operation to produce a result; and a materializing component that materializes the data structures based on the data representation that describes the data structures, wherein the materializing component identifies an optimal amount of data to materialize based on current processing resource use for the system such that determined current need for the data is balanced against processing resource use, deferring materializing of an optimal portion of the data structures into memory until after the inferred operation is determined and the data portion is indicated as being needed when balanced with the current processing resource use.