6H. function values
-------------------
With v3, you can also have functions as values, and pass these
freely around. they're different from quoted expression, since
they're called just like normal PROCs. example:

fun:={myproc}			-> get PROC ptr

...

fun(1,2,3)			-> apply to args, just like normal PROC

notes:
- you have to be sure that the PROC you have a ptr to and the
  number of args are the same. the compiler can't check this for you.
- even worse: you have to be sure the ptr is a PROC at all.
  there is a compiler warning that may help you with this.