[MLton] WideChar?

[Henry Cejtin]

Did you mean to use the case of the U/u in \U and \u to distinguish between
the 4 and 8 nibble case?  I guess I feel like these escapes should be
sufficiently rare that always using 8 would be ok, but I don't care much.
I always felt that it was a bit silly that I could not have a tab character
in ML strings literally, but had to use \t.  Often that is what I would use
any way, but not always and the restriction seems silly.