Re: [patch, fortran] Handling of .and. and .or. expressions

[Janne Blomqvist <blomqvist dot janne at gmail dot com>]

On Wed, Jun 27, 2018 at 8:26 PM, N.M. Maclaren <nmm1@cam.ac.uk> wrote:

> On Jun 27 2018, Janus Weil wrote:
>
>> What is so complicated about putting a statement into the Fortran
>> standard that says: "Ok, if this function has side effects, we
>> definitely must evaluate it, otherwise we lose the side effects. They
>> might be important."  ???
>>
>
> Because that would mean a complete redesign of Fortran's semantic model
> of execution.


If the semantic model is unclear on whether a function with potential
side-effects might or might not be evaluated, then IMNSHO the semantic
model is shit, and should be fixed or replaced.


> It would also NOT be what a lot of people want.


Huh? Who wants that? And why??


>   Inter
> alia, you would have to define what a side-effect is - and my point
> about IEEE 754 is very relevant here.
>

AFAIU most languages that take purity seriously, including in particular
Haskell, explicitly consider the IEEE exceptions outside the purity model.
Similarly, evaluating a pure expression might cause you to run out of
memory and the program is killed, which is most definitely a side-effect
but not one that is taken into account in the Haskell concept of purity.

I could certainly live with such compromises on purity, and I don't think
those examples are a good excuse to do nothing.


-- 
Janne Blomqvist