define-extension-compiler (symbol (&rest lambda-list) &body body)

symbol -- The name of the extension, a symbol
lambda-list -- A destructuring lambda list, optionaly augmented using &environment
body -- Lisp forms, an implicit progn

Defines symbol as a name to be used in Xuriella's sexp representation for XSLT.

It used when XSLT in sexp syntax includes a list of the form:

 (symbol ...arguments...)  

The list arguments is then destructured using the specified lambda list, and body is invoked during compilation time as an implicit progn.

body should return a function of one argument, which will be called at run time with a context object as an argument.