Char literals

[Eldar Insafutdinov]

I've just written a simple replicate function (the one from std.range does not work in CTFE):
T[] replicate(T)(int n, T value)
{
    T[] ret;
    if (n > 0)
    {
        for(int i = 0; i < n; i++)
            ret ~= value;
    }
    return ret;
}
it's not the best implementation, but that's not the thing I want to say today. When I call it

string str = replicate(5, 'a');

I get

moc.d(370): Error: cannot implicitly convert expression (replicate(5,',')) of type char[] to string

That means that char literals are "char", but not "immutable(char)". I remember the whole conversation about array literals, but char literals are closer to those of the string. What's the reasoning behind leaving them as mutable char?