It is, therefore, possible to extend a partially specified interpretation to a complete interpretation, without loss of verifiability, [...] This fac… - Robert W. Floyd

To the designer of programming languages, I say: unless you can support the paradigms I use when I program, or at least support my extending your language into one that does support my programming methods, I don't need your shiny new languages. [...] To persuade me of the merit of your language, you must show me how to construct programs in it.

The establishment of formal standards for proofs about programs [...] and the proposal that the semantics of a programming language may be defined independently of all processors for that language, by establishing standards of rigor for proofs about programs in the language, appears to be novel.

If there is ever a science of programming language design, it will probably consist largely of matching languages to the design methods they support.