A theory of interpretive architectures: some notes on DEL design and a Fortran case study

An interpretive architecture is a program representation that peculiarly suits a particular high level language or class of languages. The architecture is a program representation which we call a directly executed language (DEL). In a companion paper we have explored the theory involved in the creation of ideal DEL forms and have analyzed how some traditional instruction sets compare to this measure. This paper is an attempt to develop a reasonably comprehensive theory of DEL synthesis. By assuming a flexible interpretation oriented host machine, synthesis involves three particular areas: (1) sequencing; both between image machine instructions and within the host interpreter, (2) action rules including both format for transformation and operation invoked, and finally, (3) the name space which includes both name structure and name environment. A complete implementation of a simple version of FORTRAN is described in the appendix of the paper. This DEL for FORTRAN called DELtran comes close to achieving the ideal program measures.