Why is GC.collect `pure`

[Nick Treleaven]

On Wednesday, 2 August 2023 at 17:55:12 UTC, Nick Treleaven wrote:
> On Wednesday, 2 August 2023 at 17:52:00 UTC, Nick Treleaven 
> wrote:
>> Now I'm wondering why those functions are marked `pure` - they 
>> must affect the GC's bookkeeping state.

I guess it was because the GC's internal state is not supposed to 
be observable outside internal GC functions. I find it harder to 
accept some of those than `GC.malloc` being pure, because 
GC.disable and GC.enable will affect how long future allocations 
will take. That latency can be significant and observed by the 
program. Also conceptually they are changing GC state.