On Mon, Nov 17, 2008 at 9:49 PM, Maurício <span dir="ltr"><<a href="mailto:briqueabraque@yahoo.com">briqueabraque@yahoo.com</a>></span> wrote:<br><div class="gmail_quote"><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
> (...) I don't recall where I found the following example, but copied<div class="Ih2E3d"><br>
> it locally as compelling evidence that the functional solution can be<br>
> much clearer and shorter than the same solution modeled with objects<br>
> and inheritance.<br>
<br></div>
Greg,<br>
<br>
I desagree with you. Bjarne Stroustrup, the original creator of C++, is<br>
a sensible person and I share his peacefull opinion in this matter:<br>
<br>
<a href="http://www.research.att.com/%7Ebs/bs_faq.html#compare" target="_blank">http://www.research.att.com/~bs/bs_faq.html#compare</a><br>
<br>
Even with good intentions, I've never seen such kind of comparison not<br>
to fall into religious fights. (Although I'm not more than just a humble<br>
language user.)<div class="Ih2E3d"></div></blockquote><div><br>Functional languages are much more formalized than OO languages. The basics (i.e. lambda-calculus algebraic data-types, *morphisms) are well known and very composable. OO theory is a mess, classes and objects are different beasts on every OO language and they don't form an easily composable toolkit (e.g. the inheritance vs. composition debate, where to place methods, binary method choices). There are many (which by sheer amount of variance isn't a good sign) formalizations of OO but none that were well received by the most popular OOPLs (in contrast with FP theory and it's pervasiveness in FPLs).<br>
<br>In this case it isn't a religious fight.<br> </div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><div class="Ih2E3d"><br>
> -- Arithmetic expression forms data Expr = Num Int | Add Expr Expr<br>
><br>
> -- Evaluate expressions<br>
> eval :: Expr -> Int<br></div>
> (...)<div class="Ih2E3d"><br>
<br>
> public abstract class Expr {<br>
> public abstract int eval ();<br>
> public abstract void modn(int v);<br>
<br></div>
Although I'm not good enough to judge anyone's Haskell code, the Haskell<br>
version seems nice. I don't know how someone who understands well<br>
object-oriented code would do that. But I did C++ until around 1998,<br>
when the first standard was set, and I can tell you for sure that, even<br>
at that time, no one who knows at least the basics of C++ would ever<br>
write that problem like this.<br>
</blockquote><div> <br>Well, any OO programmer familiar with algebraic and coalgebraic datatypes would do that, it's the best way to model this problem (unless you mix it with extensible types but then we would fall in the expression problem territory and this isn't an easy problem to solve in any mainstream languages).<br>
<br></div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Best,<br>
Maurício</blockquote></div><br>Best regards,<br>Daniel Yokomizo<br>