Hi Jürgen, When James A. Brown wrote APL2, he based his arrays on Trenchard More's "Array Theory", an attempt to give nested rectangular arrays an axiomatic foundation equivalent to that of set theory. The major implementation of this idea is in the language NIAL, of which Q'NIAL is a popular incarnation.
I haven't read More's paper, but I would assume that for array theory to be consistent, enclose of a non-simple scalar can't be a no-op, because disclose of a non-simple scalar isn't a no-op, and enclose and disclose need to be inverses of each other. Regards, Mike
