Proposal: Relax rules for 'pure'

[Don]

Steven Schveighoffer wrote:
> On Thu, 23 Sep 2010 08:47:36 -0400, Robert Jacques <sandford at jhu.edu> 
> wrote:
> 
>> On Thu, 23 Sep 2010 02:51:28 -0400, Don <nospam at nospam.com> wrote:
>>
>>> Jesse Phillips wrote:
>>>> Steven Schveighoffer Wrote:
>>>>> If we can define weakly pure functions this way, they most likely 
>>>>> will be  way more common than unpure functions.  I know I avoid 
>>>>> accessing global  variables in most of my functions.  Think about a 
>>>>> range, almost all the  methods in a range can be weakly pure.  So 
>>>>> that means you need to mark  every function as pure.
>>>
>>> I think that's true. I/O is impure, but most other things are not.
>>
>> The GC also impure :)
> 
> The GC must be assumed to be pure even though it's not.  Otherwise, pure 
> functions can't do any heap allocation, and that makes them pretty 
> useless in a garbage collected languages.
> 
> In functional languages, allocating memory is usually considered pure.

In the D spec, it already says that 'new' is considered pure.