Question

I know D already has while loop, but because of its advanced features I would like to see what it would look like if while loop was implemented in code.

motivation: the accepted answer to this question on SO.

Answer 1

Using lazy function parameters:

void whileLoop(lazy bool cond, void delegate() loopBody) {
Begin:
    if(!cond) return;
    loopBody();
    goto Begin;
}

// Test it out.
void main() {
    import std.stdio;

    int i;
    whileLoop(i < 10, {
        writeln(i);
        i++;
    });
}