Automatic data structure choice in a language of very high level

SETL is a set-theoretically oriented language of very high level whose repertoire of semantic objects includes finite sets, ordered n-tuples, and sets of ordered n-tuples usable as mappings. This paper describes the structure of an optimizer for this language. Among other methods of interest, the optimizer uses techniques which allow relations of inclusion and membership to be established, the domains and ranges of (tabulated) mappings to be estimated from above and below, and the single-valuedness of (tabulated) mappings to be proved. Once facts of this kind have been established, automatic choice of data structures becomes possible. The methods employed are based upon, and extend, known techniques of data flow analysis.