Ceylon language

[Andrei Alexandrescu]

On 4/13/11 3:03 PM, Nick Sabalausky wrote:
> "bearophile"<bearophileHUGS at lycos.com>  wrote in message
> news:io458e$elr$1 at digitalmars.com...
>>
>> Ceylon does not support method overloading (or any other kind of
>> overloading).
>>
>
> Eewww. Haxe is like that and it's nothing but a royal pain in the ass.
>
>>
>> If a value of type T can be null, it must be declared as type Optional<T>,
>> which may be abbreviated to T?
>>
>> String? name = process.args.first;
>> if (exists name) {
>>     writeLine("Hello " name "!");
>> }
>> else {
>>     writeLine("Hello World!");
>> }
>>
>> Use of an optional value must be guarded by the if (exists ... )
>> construct. Therefore, NullPointerExceptions are impossible.
>>
>> This is exactly what I suggested for D in a enhancement request.
>> It seems this kind of stuff is becoming a standard in new languages.
>>
>
> Yes, I'd *love* to see that in D, too.

I think you'd be hasty. As Kagamin mentioned, this ad-hoc guarding works 
straight against modularity. Also, without more details I can't really 
say, but if the type of the checked variable doesn't automagically 
change from T? to T inside the guarded code, a lot of subsequent uses 
(pass down to functions etc.) would have to repeat the check. Also, if 
the variable is reassigned it would have to change back the type from T 
to T?, which makes program understanding by both human and compiler 
(e.g. "do I need a test here?") a bitch.

I'm highly skeptical of this feature in particular. I'm even more so 
because it's the kind of ad-hoc feature with many fuzzy corners that 
needs solid real-world validation, which... ("You can’t write code in 
the language just yet!") doesn't exist.


Andrei