Function calls

[bearophile]

I have written the following closure, to generate numbers in 1-7 from numbers in 1-5, as alternative implementation of this:
http://rosettacode.org/wiki/Seven-dice_from_Five-dice#D

auto dice7Gen(alias d5)() {
    int rem = 0;
    int max = 1;

    int gen7() {
        while (rem / 7 == max / 7) {
            while (max < 7) {
                int rand5 = d5() - 1;
                max *= 5;
                rem = 5 * rem + rand5;
            }

            int groups = max / 7;
            if (rem >=  7 * groups) {
                rem -= 7 * groups;
                max -= 7 * groups;
            }
        }

        int result = rem % 7;
        rem /= 7;
        max /= 7;
        return result + 1;
    }

    return gen7;
}

Can you spot the bug? It returns an integer instead of a closure :-)
The correct last line has to be:
    return &gen7;

But I think the real "bug" here is in the D2 design. In D2 calling callables without () has to be disallowed:
- & to take their reference/address
- () to call them
Otherwise syntax error at compile-time.

Only properties marked with @property are allowed to be called without (). (If you really want it, then even free functions may be allowed to be marked with @property. This probably will not cause many bugs).

This can avoid bugs and tidy the language a little more.

Bye,
bearophile