Dynamic, continuable, and abortable collecting.
JSON library using algebraic data types.
LETREC in Common Lisp.
Random things written in Scheme
CFFI bindings to the MPFR (http://www.mpfr.org/) library for multiple-precision floating point numbers.
Set-like data structure using maps.
A library of algebraic data types using CL-ALGEBRAIC-DATA-TYPE.
Abstractions for working with generator-like objects.
On Various Topics
Implementation of Dancing Links, Donald Knuth's efficient implementation of Algorithm X for solving the exact cover problem