Website message overhaul

[Brad Anderson]

On Mon, Nov 14, 2011 at 1:29 PM, Timon Gehr <timon.gehr at gmx.ch> wrote:

> On 11/14/2011 08:47 PM, Andrei Alexandrescu wrote:
>
>> On 11/14/11 1:15 AM, Timon Gehr wrote:
>>
>>> Looks good, I think this is the right direction.
>>>
>>> Nitpicks:
>>>
>>> 1.
>>>
>>> // Type deduction works for function results. This is important for
>>> generic
>>> // functions, such as min below, which works correctly for all comparable
>>> // types.
>>> auto min(T1, T2)(T1 lhs, T2 rhs) {
>>> return rhs < lhs ? rhs : lhs;
>>> }
>>>
>>> It does not. The two types need to have a common type as well.
>>>
>>
>> It's difficult to be concise and complete simultaneously. The underlying
>> assumption is that if two types are comparable, they also have a common
>> type.
>>
>
> hm, maybe call the them 'compatible comparable types'?
>
>
>
>>  2.
>>>
>>> The scope statement example should actually show transactional code.
>>> Otherwise the poor reader feels fooled into clicking "See example".
>>> Using scope(exit) to write something at function exit is useful for
>>> debugging, but scope(failure) is the real thing that is important to
>>> show.
>>>
>>
>> Good point.
>>
>>  3.
>>>
>>> If contract inheritance is to be promoted on the front page (and it is
>>> certainly something that may attract developers), it should actually
>>> work.
>>>
>>
>> Absolutely.
>>
>
> There has been disagreement on whether or not my bug report on the matter
> was valid.
>
> What it means for your example:
>
> // Interfaces and classe
> interface Printable {
>    void print(uint level)
>    in { assert(level > 0); } // contract is part of the interface
> }
>
> // Interface implementation
> class Widget : Printable {
>    void print(uint level) { ... }
> }
>
> void main(){
>    Widget w = new Widget();
>    w.print(0); // passes through, but should not
> }
>
> Can you state in the issue tracker that the bug report is valid?
> http://d.puremagic.com/issues/**show_bug.cgi?id=6856<http://d.puremagic.com/issues/show_bug.cgi?id=6856>
>
>
>
>
>>  4.
>>>
>>> If we can find a less buzzy word than 'Multi-paradigm power' to describe
>>> D's multi-paradigm power, that would be nice, but I am also fine with
>>> the current state of affairs.
>>>
>>> 5.
>>>
>>> The most important language features are not displayed at all. Where are
>>> Metaprogramming, CTFE and code generation? It sure is hard to come up
>>> with a short but convincing example, but I think we should try to.
>>>
>>
>> Those would be under the multi-paradigm thingie.
>>
>>
> Ok. Maybe there could be a few LOC demonstrating the 'recurrence' function
> generating a few fibonacci numbers. I think it is a nice showcase, although
> I have never needed that particular function in real code :o). It has also
> the potential of showing Phobos' lazy functional style features. But
> unfortunately, most functional programmers will shriek for a moment when
> they see the argument order of 'take'.
>
>
>
I think that's a good idea.  While learning D I became impressed with it
when I solved Project Euler problem 2 ("By considering the terms in the
Fibonacci sequence whose values do not exceed four million, find the sum of
the even-valued terms.") with:

auto answer = reduce!"a + b"(filter!"a % 2 == 0"(until!"a >
4_000_000"(recurrence!"a[n-1] + a[n-2]"(1, 1))));

It'd look better with UFCS but it's still rather neat I think.
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