D. Tweed wrote:
On Thu, 26 Jul 2001, Frank Atanassow wrote:
My reaction to that is: you are not programming in C. If you restrict yourself to nice subsets of a programming language, then obviously your programs will satisfy better properties.
That's certainly a resaonable position to take. All I'm saying is that in a purely pragmatic sense, if we say that I'm not programming in C, what proportion of the people out there who compile their programs with C compilers aren't programming in C either?
Interesting point. That says something about C.
I still think that, from the purely pragmatic point of view of giving arguments as to why someone using an imperative language (in the way that people actually do use those languages, _rather than in a way that they conceivably could use them_,) would be better off using a functional language it's more convincing to argue about the problems that _actually do affect them_ and can be handled better in a functional language than to talk about the extreme problems that very rarely occur in practice.
I could agree that that follows, but I have no evidence that all or even most C programmers program in the same restricted subset, or any proper subset at all.
I've never written a Haskell program using functional dependencies, or existential classes, ...
I find them indispensible, and I know for a fact that I am not the only one around our office who feels that way. Though, the people around here (Utrecht's software technology group) are not exactly typical programmers... :)
Clearly that would be true, but there's a really extreme clumpiness in the distribution over the state space: virtually all my programs are written in the same sublanguage.
I can believe this holds for your programs, but, uh... your clumps are not necessarily in the same place as other people's clumps. Please don't misinterpret that. :)
So, in the limit you might specialize your `language' differently to every single program you write. By that token, then, all programming languages become equal, and we have reduced this discussion to triviality.
That sounds nice in principle.
<sigh> Everything I say seems to sound nice in principle. Maybe I am just a hopeless idealist... Anyway, the point of my quoted remark above was that I would like to have more concrete boundaries for evaluating languages. I was trying to demonstrate that equating the properties of a language with the properties of any of its subsets is nihilistic. I gather that your claim is that most C programmers use the same subset, or at least one among a family of subsets.
do I face lots of problems and bugs due to all the weird and excessive `cruft' in the C language? I still honestly believe that I don't: most of the problems that I face would be exactly the same in a much simpler imperative language. And I think they're fundamentally due to the imperative assignment has a (simple to state and understand) semantics which simpy cannot be used to reason effectively about programs.
Hallelujah! I understand what you're saying now! You're saying that C is bad, not because of the cruft, but because of assignment. Correct?
I am not denying that you can have a nice imperative language (although I think that `just' a global store is too unstructured to support good metaproperties for reasoning).
Ah, that's strange because I _am_ asserting that. What I'm asserting is that it's the very fundamental concepts like assignment to variables that make effective reasoning very difficult for most of the bugs that actually occur in the code that people write.
OK, I understand. I used to share this view, and I agree except that I don't think assignment is bad, only unrestricted assignment on a global store. What convinced me is this paper, which you should read: @article{ reddy96global, author = "Uday S. Reddy", title = "Global State Considered Unnecessary: An Introduction to Object-Based Semantics", journal = "Lisp and Symbolic Computation", volume = "9", number = "1", pages = "7--76", year = "1996" } You can get it here: ftp://cs.uiuc.edu/pub/faculty/reddy/papers/global.object.ps.Z --- Frank Atanassow, Information & Computing Sciences, Utrecht University Padualaan 14, PO Box 80.089, 3508TB Utrecht, The Netherlands Tel +31 (0)30 253-3261 Fax +31 (0)30 251-3791