The most beautiful I'm aware of is Robert Strandh's SICL (https://github.com/robert-strandh/SICL https://github.com/robert-strandh/SICL). CL-PPCRE (https://gith

The most beautiful I'm aware of is Robert Strandh's SICL (https://github.com/robert-strandh/SICL https://github.com/robert-strandh/SICL). CL-PPCRE (https://github.com/edicl/cl-ppcre https://github.com/edicl/cl-ppcre) is very nice as well, imo. What makes them beautiful? They're very straight forward and clearly communicate what they're doing, and how. And the parentheses in their language of choice softens the visual display of the code -- while the semantics of the language cause the shape of the code to communicate quite a bit about how the machine will go about executing it. There are no surprises. In terms of conceptual beauty, it'd be hard to beat Screamer (https://github.com/nikodemus/screamer https://github.com/nikodemus/screamer). What makes this beautiful? The way it makes a hairy problem seem simple and straight-forward.