Postscript: You might well ask why not just use "=" only, and assume that all definitions are potentially self-referencing? That's a non-starter because I fin

Postscript: You might well ask why not just use "=" only, and assume that all definitions are potentially self-referencing? That's a non-starter because I find that redefinition is the more common intent: \x=4 \x=(* x 5) \x=(+ y x) In those cases I don't want x defined in terms of itself, but rather in terms of the previous definition of x. That is why I would insist on a special token such as "==" to express the intention of self-reference.