Some syntactic methods for specifying extendible programming languages

Our model of a programming-language translator system is represented schematically in the block diagram of Figure 1. This diagram divides the translator system into two components. The first component T is a translator program that reads in and translates the valid programs of some programming language L. The output of the translator is a subset T(L) of the intermediate language. The second component is a system M for executing the programs translated into the intermediate language. It will be seen that, in this intermediate language, the operators follow their operands in postfix (reverse polish) form, and they are relatively machine independent. In this paper, we will be mainly concerned with defining the operation of the translator component by specifying the input-output relationships of the translator for a particular programming language. These relationships will be described in a syntactic notation that is independent of the particular translation algorithm used for implementing the translator T.