Pure functions in D

[BCS]

Reply to Jason,

> You're missing the subtleties in what Walter said:
> "If memory allocation failure is a non-recoverable exception,
> then pure functions can allocate memory."
> That means that if an out of memory exception occurs, the pure
> function (possibly even the whole program) can not catch the out of
> memory exception.  Either a pure function will operate normally and
> predictably, or it has a non-recoverable error.  This has to be
> handled differently than recoverable errors/exceptions which are
> predictable/repeatable.
> 


Ditto. To argue the point by taking it to the ridiculous: *Any* function 
can fail for any number of reasons that aren't related the to arguments; 
stack overflows, un-handled external signals (SIGKILL), loss of power to 
the the CPU, arbitrary hardware failure. The line has to be drawn somewhere, 
the question is only where.