Thanks for the pointers. I'm also about halfway through "Higher Order Perl" which seems to give a few nuggets as well (although the first chapters are a pretty long rehash of recursion). It's become clear that part of my struggle is figuring out the Perl syntax around lists and subroutines (e.g. used in closures). I'm good with hierarchical anonymous structures, but clearly some of my lack of precise syntactical knowledge is holding me back. Anyway, thanks for all the pointers!