If I hear data structure lisp code is not on my mind, so it's rather an API or a drawing library?
What am I manipulating exactly?
; context start
(with-snek (snk)
Do you plan to write an API documentation?
Most Lisps, especially Common Lisp which inconvergent is using, have plenty of data structures: http://www.lispworks.com/documentation/lw70/CLHS/Front/Conte...
Common Lisp doesn't have a nice literal structure for hash tables/maps/dicts but that is easily mended with a macro.
"(with-snek (snk) ..." is a macro which abstracts away lower level tedious boilerplate. It hands you "snk" on a platter so you can manipulate it.
Common Lisp itself also comes with some of these macros: http://www.lispworks.com/documentation/lw70/CLHS/Front/X_Alp...
"with-open-file" (skip to the examples) is a nice one since it takes care of opening and closing the file for you so you can write your block of code inside of it and be sure the file gets opened and closed properly:
(with-open-file (f "/path/to/file" :direction :output :if-exists :supersede)
... your code writing to "f" comes here ...
)snk is an instance of snek, so it contains a realisation of the structure and its current state.