lispdoc - results for function-lambda-expression

(function-lambda-expression fun)
Function: Return (VALUES DEFINING-LAMBDA-EXPRESSION CLOSURE-P NAME), where DEFINING-LAMBDA-EXPRESSION is NIL if unknown, or a suitable argument to COMPILE otherwise, CLOSURE-P is non-NIL if the function's definition might have been enclosed in some non-null lexical environment, and NAME is some name (for debugging only) or NIL if there is no name.
Example:
(defun ajax-function-name (fn)
  (or (sb-kernel:%fun-name fn)
      (string
       (nth-value 2
                  (function-lambda-expression
                   fn)))))
Mentioned in:
CLtL2 - 25.1. The Compiler
HyperSpec - Function FUNCTION-LAMBDA-EXPRESSION