optimization of list comprehensions

[Ulf Wiger (AL/EAB)]

I've seen many examples of how people use
list comprehensions as a form of beautified
lists:foreach() - that is, they don't care
about the return value of the comprehension.

I hesitate to say that it's bad practice,
even though one will build a potentially
large list unnecessarily, since it's 
actually looks a lot nicer than using 
lists:foreach().

Question: would it be in some way hideous
to introduce an optimization where such
list comprehensions do everything except
actually build the list? Then they could
execute in constant space.

/Ulf W