- COLLECTING - LOOP has a COLLECT clause which is nice and handy
- collectors - collectors is a common lisp library that aims to ease accumulating values (similar to loop/iter's collecting / appending clauses)
- General accumulator - General-purpose, extensible value accumulator library
- group-by - Group-by is a Common Lisp library to help group data into trees (of various formats) based on common/shared values
- track-best - There are several libraries that support collecting things generated in loops (e.g
Accumulators are libraries that help aggregate values by building lists, strings, or other data structures out of the pieces.