[Haskell-beginners] general comments requested

[Stephen Tetley]

Hi Michael

It looks fine - with one big exception.

Tracking down /undefined/ can be quite tedious, there is no indication
at run time which particular undefined signalled the exit - I'd
recommend you always throw an error with an identifiable string.

Also, I wonder if the the MusicXML library on Hackage was
auto-generated at least in part?

It would be nicer to work with if it used constructors and
field-labels more, rather than long tuples; though there isn't much
you can do about that.

Best wishes

Stephen