[plt-scheme] lazy query lang

looking for pointers towards downloadable implementations of lazy query
language libraries for ml, ocaml, haskell, or scheme

kleisli / cpl seem to be what i'm looking for, but they are commercial.
i don't need anything very robust, just something that allows you to
define   datasources (files or possibly tables) and express queries in
a comprehension-ish format. then incrementally run the queries. 

might just roll my own if i have to.