Open vs. Closed Lists
lTwo list models are
described in the text:
lOpen lists:
lElements and sublists can be
shared
lMutation of lists is
discouraged
lMathematically
elegant
lClosed lists:
lSharing generally not
done
lMutation of lists is ok,
because they are encapsulated
lMathematically less
attractive
lClosed lists can be built by
wrapping open lists