John David Stone writes:
R6RS provides libraries for hash tables and bitwise operators — very good! Its (rnrs lists) library standardizes the names and interfaces of some very important higher-order procedures — for-all, exists, filter, fold-left, fold-right — while the proposed R7RS doesn't support any of these. Of course, we teachers can always write our own libraries to support them, as apparently we're going to have to continue to do for random-number generation. My guess is that the implementers will do at least as good a job.