GC.malloc is pure - wat

[Steven Schveighoffer via Digitalmars-d]

On 4/24/15 4:42 PM, deadalnix wrote:
> On Friday, 24 April 2015 at 19:41:21 UTC, Steven Schveighoffer wrote:
>> On 4/24/15 3:12 PM, deadalnix wrote:
>>> On Friday, 24 April 2015 at 18:48:43 UTC, Steven Schveighoffer wrote:
>>>> I think you are thinking of @safe-ty. malloc and free can be pure, but
>>>> must be contained properly.
>>>>
>>>> purity when it comes to mutable data is a tricky thing.
>>>
>>> No, it should not be pure because it alter global state in a manner
>>> visible to the program.
>>
>> But so does GC.malloc.
>>
>
> No, that's the whole point of using a GC. You ask it for a chunk of
> memory, it gives you a chunk of memory. This does not affect any other
> part of your program as it is a NEW chunk of memory, so you are not
> messing with your program state.

But I can check memory usage size and see global state has been altered.

> When you free, you potentially alter references anywhere outside your
> "pure" function. It must not be pure.

When you do ANYTHING to mutable data, you potentially alter references 
outside your pure function. This is not a disqualifier. It's accessing 
global sate directly that wasn't passed to you that is a disqualifier.

-Steve