forcing compile time function execution

[Joshua Reusch]

Am 27.12.2011 20:51, schrieb Vladimir Panteleev:
> On Tuesday, 27 December 2011 at 19:46:31 UTC, Joshua Reusch wrote:
>> Am 27.12.2011 20:35, Vladimir Panteleev wrote:
>>> Halting problem?
>>
>> Makes an not-stopping pure function really sense?
>
> No, but you don't know if the user is expecting the function to take a
> long time to run, or it's stuck due to a bug.
>

If the function gets evaluated at compile-time, also the loop/recursion 
conditions are known.

>> If you evaluate a function creating an infinite loop at compile-time,
>> you get for sure in this state. Then, the compiler could stop the
>> evaluation after some time and print an error/warning or creates
>> runtime code.
>
> The problem is with "after some time". It's not possible to know when
> the compiler should stop. For all it knows, the user is doing some
> compile-time raytracing.

ok, "after some time" is really not the right approach. But as I wrote 
above, the compiler knows the conditions for loops. The function also is 
pure, so it should have the same behaviour with the same arguments. With 
a function calling stack it should be possible to detect infinite 
recursive calls.