Re: using <subprogram>'address for callback

[4526P@NAVPGS.BITNET ("LT Scott A. Norton, USN")]

( Please excuse me if I have a Pascal accent; I still can't write
Ada without the book open in my lap. )

The disscussion on X-windows, particularly callbacks, has
reawakend my interest in one of the design decisions from
Steelman.  The particular feature of Ada that caught my eye, when
I first was learning the language, was that a procedure could not
have a function or another procedure as a formal parameter.  I
don't think that "integrate( f, a, b )" is poor software
engineering, but you can't do that directly in Ada.  The Ada
solution I saw in one text for integrating a function involved
generics, but that seem kludgy to me.  So, I'm asking:

 1. Why does Ada not permit functions as formal parameters?

 2. Is there some other clean way to model functionals ( functions of
    functions ) besides instantionating a generic for each pair of
    functional and its argument function?

I realize that sometimes, a programming model that works well in
one context produces serious inconsistancies in another.  And so,
we don't see Algol-60 call by name anymore.

LT Scott A. Norton, USN
Naval Postgraduate School
Monterey, CA 93943-5018
4526P@NavPGS.BITNET