Re: Is strong typing worth the cost?

["Marin David Condic" <dont.bother.mcondic.auntie.spam@[acm.org>]

This is a legitimate question to ask. There are lots of theories and
reasoning about theories that tend to give one cause to believe that strong
typing (and other aspects of Ada) lead to lower costs and higher
reliability. However, that's different than some emperical evidence that in
the real world you actually *do* get the benefit claimed by the theories.
There can be lots of factors in the real world that tend to mess up the
theories.

Example: Automotive research indicates that antilock breaking systems ought
to reduce accidents. Yet there have been some recent studies of accident
statistics that would seem to indicate that cars equipped with ABS actually
end up in *more* accidents than other cars. Why is that? The engineers will
have to puzzle over it for a while to see if they can explain the
phenomenon.

The bad news is that there is a real dearth of any empirical evidence to
support most of the claims made by theoreticians and practitioners in
software engineering. There is a lot of anecdotal evidence - but that gets
weak. (Think of the last time some politician parades some pathetic,
suffering family out in front of the news cameras to justify why he wants to
pass some bill & spend some truckload of (our) money "to help these poor,
suffering people..." Does finding one single case where a program might be
of benefit justify the whole program?) There have been some studies here and
there, but not necessarily in the areas of interest and certainly not
consistently enough to really make the conclusions "scientific".

There have even been some economic studies at Harvard that indicate that
computerization does not benefit a company. Dollars in to purchase PC's,
etc., for a company do not necessarily translate into dollars out in
profits.

The good news is that Ada seems to have more empirical evidence of
productivity/error improvements than most other languages. Maybe we Ada fans
are just more "scientific" than most? :-) I had in-house data indicating Ada
improved things over other languages and there are other studies that seem
to support that conclusion out there on the net. (McCormick & Rational being
the two most frequently referenced.) But those are at a gross level of "Ada
vs Something Else" so you can't really claim it proves that strong typing
itself is a good thing.

My study looked at error rates and found a huge decrease there. Review of
the errors indicated that a large percentage of them were due to numerical
scaling errors and such that went away with Ada's support for representation
of numbers & strong typing. (The representation of fixed point numbers and
the use of well defined floating point numbers and the ability of the
compiler to do the conversion work for you were all major factors in
eliminating errors.) A reduction of errors translates into increased
productivity as well since you aren't spending time patching things.

The problem is that this was just in one domain where the numeric problems
are a really big deal & wouldn't necessarily reflect the rest of the world.
(That, and the study was completely internal so I can't give you references
you can cite. :-) It would be interesting to see if any of the academic
types out there with an interest in Ada could come up with some experiments
or studies that could provide some solid evidence for Ada's claims to doing
it "better".

MDC
--
Marin David Condic
Senior Software Engineer
Pace Micro Technology Americas    www.pacemicro.com
Enabling the digital revolution
e-Mail:    marin.condic@pacemicro.com


"dmjones" <derek@NOSPAMknosof.co.uk> wrote in message
news:Xns9200929868B11derekknosofcouk@62.253.162.107...
>
> Why am I asking for this evidence?  I am working on a detailed
> analysis of C that includes material on coding guidelines.
> I have set myself the target of basis these guidelines on
> empirical evidence.  I am a fan of strong typing.  However,
> unless I can find any evidence to the contrary, the most I
> can say at the moment is "some people think ...".
>