6th February 1970
Dear WG2.3 Member,
A copy of EWD249 "Notes on Structured Programming" has been mailed to you under separate cover, as underlying material for the Copenhagen meeting of WG2.3. I beg you to read it as carefully as you think it deserves to be read, as I am very anxious to get whatever comments you feel tempted to make.
I am presently engaged in an investigation of what is implied by (and what benefits could be derived from) the design of a highly layered, tree-structured programming system. One of my goals is to arrange matters in such a fashion that "adding another layer to the system" at top side is very much like "feeding in a user program"; another goal is to arrange matters in such a fashion that at bottom side a number of the lower layers could (at least conceptually) be absorbed by the hardware. In its present stage, this project is hardly fit for discussion, I am just tentatively playing with vague concepts, trying to shape them so that they nicely fit together, I am still looking for the good words, the helpful metaphors.
But this work will be heavily influenced by my past thinking as reflected in EWD249 and therefore I solicit your comments most eagerly. An additional reason to ask for the benefits of your varied experience is the fact that my personal professional experience, although gathered over a considerable period of time, is very one-sided, so one-sided in fact, that I may have overlooked major implications of the programmer's task.
That is why I am grateful for the opportunity to throw EWD249 before the wolves. May the wolves enjoy it!
Looking forward to meeting you in Copenhagen,
yours ever
Edsger W.Dijkstra