functionp doc improvement

* doc/lispref/eval.texi, doc/lispref/functions.texi, src/eval.c:
Document functionp a bit more carefully.  It can return t
on non-functions.

1 files changed, 5 insertions, 3 deletions

diff --git a/src/eval.c b/src/eval.c
index 950338bf799..29c122e2fb2 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -2805,9 +2805,11 @@ apply1 (Lisp_Object fn, Lisp_Object arg)
 DEFUN ("functionp", Ffunctionp, Sfunctionp, 1, 1, 0,
        doc: /* Return t if OBJECT is a function.
 
-An object is a function if it is callable via `funcall';
-this includes primitive functions, byte-code functions, closures, and
-symbols with function bindings.  */)
+An object is a function if it is callable via `funcall'; this includes
+symbols with function bindings, but excludes macros and special forms.
+
+Ordinarily return nil if OBJECT is not a function, although t might be
+returned in rare cases.  */)
      (Lisp_Object object)
 {
   if (FUNCTIONP (object))