in reply to Hash key composition with a comma?

How very-interesting Perl might have been if this construct had been conceived as a shorthand for auto-vivification in multi-level hash data structures.   But I have no idea if the latter concept had been thought of yet.   To me, this is a “what might have been” concept but “it’s much too late to do the right thing now.”   Perl never did have a true multi-dimensional data structure.   But, way back then, what if it had?