can list comprehensions replace map?

[David Isaac]

Newbie question:

I have been generally open to the proposal that list comprehensions
should replace 'map', but I ran into a need for something like
map(None,x,y)
when len(x)>len(y).  I cannot it seems use 'zip' because I'll lose
info from x.  How do I do this as a list comprehension? (Or,
more generally, what is the best way to do this without 'map'?)

Thanks,
Alan Isaac