Super-dee-duper D features

[Andrei Alexandrescu (See Website For Email)]

Kevin Bealer wrote:
> X Bunny wrote:
>> Kevin Bealer wrote:
>>> X Bunny wrote:
>>>> Kevin Bealer wrote:
>>>>>
>>>>> 2. The syntax doesn't provide visual hints that let you read a 
>>>>> program.
>>> What I mean, is this (from the Computer Language Shootout):
>>>
>>> (defun ack (x y)
>>>   (declare (fixnum x y))
>>>   (the fixnum
>>>     (if (zerop x)
>>>     (1+ y)
>>>       (if (zerop y)
>>>       (ack (1- x) 1)
>>>     (ack (1- x) (ack x (1- y)))))))
>>>
>>> as compared to this:
>>>
>>> int Ack(int x, int y)
>>> {
>>>     if (x == 0) {
>>>         return y + 1;
>>>     } else if (y == 0) {
>>>         return Ack(x-1, 1);
>>>     } else {
>>>         return Ack(x-1, Ack(x, y-1));
>>>     }
>>> }
>>>
>>> These two things do the same thing in the same way, but the structure 
>>> and syntax make the C example much more readable.  If I want to know 
>>> input and output types, I can find them.  When I see the top of the 
>>> if/elseif/else structure, I can find each part.  It's layed out like 
>>> a table, rather than like a ball of yarn.
>>
>> If the C was indented like this would it be as unreadable as the Lisp?
>>
>> int ack(int x, int y)
>> {
>>     if(x == 0)
>>     { return y + 1; }
>>         else if(y == 0)
>>         { return ack(x-1, 1); }
>>             else {
>>                 return ack(x-1, ack(x, y-1));
>>             }
>> }
> 
> Yes - indenting badly makes it less readable in either case; I'm not 
> sure if I was indenting the LISP example in a reasonable way. (I took it 
> from someone else's page.)
> 
>> (I cant even match up all the brackets with that one!)
>>        My editor indents the Lisp like this:
>>
>> (defun ack (x y)
>>   (declare (fixnum x y))
>>   (the fixnum
>>     (if (zerop x)
>>     (1+ y)
>>       (if (zerop y)
>>       (ack (1- x) 1)
>>     (ack (1- x) (ack x (1- y)))))))
>>
>> The structure is no less obvious to me then the C. I can see the input 
>> and output types are clearly fixnums. The branches of the ifs are 
>> obvious.
> 
> Maybe one day it will be for me if I keep trying to do things in LISP, 
> but I can't shake the feeling that I'm learning to shoe horses -- a 
> skill that had its place and time.

Probably it's better comparable to harnessing a teleporting machine :o).

Andrei