String Format for Hexdecimal, custom format not supported?

It seems Island doesn’t support custom String format?

var a: Integer := 1;
writeLn(String.Format(’{0:X}’, a));

The above code doesn’t work under Island platform, throwing out an exception saying “custom string format not support”.

Any workaround?

Yeah, thats a know limitation/not a feature we have implemented in Island’s string formatter (yet?).
You can use the Convert class in Elements RTL to generate hexadecimal strings for integers, eg

writeLn(String.Format("{0}", Convert.ToHexString(a)));

or simply

writeLn($"{Convert.ToHexString(a)}");