Couldn't some of the more esoteric aspects of Icon (suspend/resume, coexpressions) be expressed as the state changes of an SECD machine, or an extension to it, or something similar? For an example of what I mean, consult (for example) Burge's book on functional programming, especially the discussions of extensions to the lambda calculus to handle a variety of messy real-life programming constructs in Algol-like languages.
