“Programming languages on the whole are very much more complicated than they used to be: object orientation, inheritance, and other features are still not really being thought through from the point of view of a coherent and scientifically well-based discipline or a theory of correctness. My original postulate, which I have been pursuing as a scientist all my life, is that one uses the criteria of correctness as a means of converging on a decent programming language design—one which doesn’t set traps for its users, and ones in which the different components of the program correspond clearly to different components of its specification, so you can reason compositionally about it. […] The tools, including the compiler, have to be based on some theory of what it means to write a correct program.”

Oral history interview http://hdl.handle.net/11299/107362 by Philip L. Frana, 17 July 2002, Cambridge, England; Charles Babbage Institute, University of Minnesota.