import std.string;
import std.stdio;

enum Foo { foo, bar }

void main()
{
    Foo foo;
    writefln("%s", foo);
    writeln(format("%s", foo));
}

Prints:
foo
0

I really think these two should be in sync with each other. It's hard to switch from writef debugging to log-based debugging when writef does one thing and format() does another.