tokenizeMeaning exit status?

[Matthew Fluet]

> The success or failure of tokenizeMeaning is communicated in the exit status
> of the command?  Or am I missing something?

fun die s
  = (Out.output(Out.error, s) ;
     OS.Process.exit OS.Process.failure)

I run die if two elements of the meaning do not match.  I also handle
exceptions in the apply function (which would correspond to IO failure, as
in the reference meaning was shorter than the checked meaning and we read
past the end of the input.  Ooh, how does that work with the meaning
coming in on stdIn?  I'm using In.inputChar.)  Otherwise, we terminate
normally, which presumably returns success.