See my updated post above with 2 cites from perldoc -f sort. They explain why you had to remeove the prototype and had to add an aditional variable $s.
s$$([},&%#}/&/]+}%&{})*;#$&&s&&$^X.($'^"%]=\&(|?*{%
+.+=%;.#_}\&"^"-+%*).}%:##%}={~=~:.")&e&&s""`$''`"e

In reply to Re^2: Choosing the sort routine on the fly by Skeeve
in thread Choosing the sort routine on the fly by grinder

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