Small readln problem

[Bradley]

Im having some starting trouble, using the code from the srd.stdio spec :
/*BEGIN CODE*/
import std.stdio;

int main()
{
    char[] buf;
    while ((buf = readln(stdin)) != null)
	writef("%s", buf);
    return 0;
}
/*END CODE*/

Im getting the following errors

>>dmd test
test.d(6): Error: undefined identifier readln
test.d(6): Error: function expected before (), not readln of type int
test.d(6): Error: cannot implicitly convert expression (readln((& _iob))) of type int to char[]

Im running a Windows 64bit machine if that helps.