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The Description of Programming Languages

Programming languages must be described syntactically and semantically. Here is the distinction. The syntactic description includes:

1. A description of the morphology, namely what symbolic expressions represent grammatical programs.

2. The rules for the analysis of a program into parts and its synthesis from the parts. Thus we must be able to recognize a term representing a sum and to extract from it the terms representing the summands.

The semantic description of the language must tell what the programs mean. The meaning of a program is its effect on the state vector in the case of a machine independent language, and its effect on the contents of memory in the case of a machine language program.

John McCarthy
Tue May 14 13:32:03 PDT 1996