I've sometimes found "map" leading me into stacking functions 'till they look like a Schwartzian Transform gone wrong, but I never have found Perl leading me towards writing at the density of a mathematical proof. Regular expressions certainly get dense and obtuse without the "/x" modifier, but they stay in their own restircted string context. Nothing's ever come close to the APL experience for leading me down the path of unintentional obscurity.