On 5/15/2014 2:41 PM, Timon Gehr wrote:
On 05/15/2014 11:33 PM, Walter Bright wrote:
On 5/15/2014 9:07 AM, Timon Gehr wrote:
Why? A memoizable function is still memoizable if it is changed
internally to
memoize values in global memory, for example.
I doubt a compiler could prove it was pure.
Yes, that was actually my point. Memoizable is actually a non-trivial property.
(But note that while a compiler cannot in general discover a proof, it could
just _check_ a supplied proof.)
If the compiler cannot mechanically verify purity, the notion of purity is
rather useless, since as this thread shows it is incredibly easy for humans to
be mistaken about it.
