Temporarily disable all purity for debug prints

[bearophile]

Adam D. Ruppe:

> Yes. In fact, I view it as better than always seeing it twenty
> times because it reflects what's actually going on.

To avoid some possible troubles I suggest to keep puts pure only in debug builds:

debug
    extern(C) pure void puts(const char*);
else
    extern(C) void puts(const char*);

pure void hello() {
    debug puts("hello world from pure land\n");
}
void main() {
    hello();
}

Bye,
bearophile