functional

[grauzone]

Andrei Alexandrescu wrote:
> On 03/10/2010 06:06 PM, grauzone wrote:
>> Andrei Alexandrescu wrote:
>>> On 03/10/2010 05:01 PM, grauzone wrote:
>>>> Andrei Alexandrescu wrote:
>>>>> There's one final nail in the coffin. In wake of concurrency, de jure
>>>>> immutability becomes a necessity, not a useful and desirable de facto
>>>>> convention. Adopting the window dressing but not the essence of FP by
>>>>> a concurrent language evokes to me a scene in the Marx Brothers: an
>>>>> otherwise impeccably-dressed gentleman who forgot to put his pants on.
>>>>
>>>> Language support is not strictly necessary to get the same effects as
>>>> immutable types, as far as multithreading is concerned: small data can
>>>> be copied, and large data can be made read-only by OS syscalls. This
>>>> just had to be in the message passing library. (As a bonus, it isn't
>>>> possible to subvert these mechanisms just by casting.)
>>>
>>> That'll never work. The OS granularity is 4KB increments.
>>
>> Data this small you would simply copy. Because it's so small, copying
>> won't have negative performance impact. The OS approach can be used for
>> large data (at least in the order of hundreds of KB) and immutable parts
>> of the data segment.
> 
> Trust me, that will never work anywhere close to satisfactory. It's even 
> useless to talk about it.

Just saying "it won't work" is a bit empty. Do you happen to have any 
arguments?

> Andrei