ABCL is an implementation of Common Lisp (CL) running in the JVM: it can run in the same JVM as your Java code, allowing full mixture of Lisp and Java code.
Being a full CL implementation, it runs many existing libraries and applications, such as Maxima, a computer algebra system.
With support for JSR-223, you easily extend any JSR-223 compatible application with Lisp as a macro language. This includes integration with the Ant build system using its script-tag.
ABCL features both an interpreter and a compiler which compiles into jvm byte code.