lispdoc - results for warn

(warn datum &rest arguments)
Function: Warn about a situation by signalling a condition formed by DATUM and ARGUMENTS. While the condition is being signaled, a MUFFLE-WARNING restart exists that causes WARN to immediately return NIL.
(defun test-unknown-word (word)
  "Print a warning message if this is an unknown word."
      (or (gethash word *words*) (numberp word))
    (warn "~&Unknown word: ~a" word)))
Mentioned in:
CLtL2 - 24.1. General Error-Signaling Functions
CLtL2 - 25.1.1. Compiler Diagnostics
CLtL2 - 27.5. Compiling Format Control Strings
CLtL2 - 29.3.18. Printing Conditions
CLtL2 - 29.4.1. Signaling Conditions
CLtL2 - 29.4.10. Restart Functions
CLtL2 - 29.4.7. Establishing Restarts
CLtL2 - 29.4.9. Warnings
CLtL2 - 29.5. Predefined Condition Types
HyperSpec - Function WARN
PCL - other uses for conditions