durendal

"Count Roland smites upon the marble stone;
  I cannot tell you how he hewed it and smote;
  Yet the blade breaks not nor splinters, though it groans;
  Upward to heaven it rebounds from the blow."

–From The Song of Roland
(Translated by Dorothy Sayers, Viking Penguin, NY, NY, 1957)

Durendal is a bucket of tricks for Clojure that are too
implementation-specific to go in Slime proper but too fancy to go
in clojure-mode itself.