How does one tell if something is a function?

>But in your example, who typed in $f?  If it goes
>through the same reading process as on line %i1,
>then it should be the same symbol, no?
>
>RJF

Apparently, so. The following seems to work

(defun $mfboundp (f)
  (if (mfboundp f) t nil))

(%i1) load("mfboundp.lisp");
(%o1) c:/maxima/maxmin/mfboundp.lisp
(%i2) f(x) := x$
(%i3) mfboundp(f);
(%o3) true
(%i4) mfboundp(g);
(%o4) false
(%i5)

Thanks,

 Barton