[Haskell-cafe] Set of reals...?
Benjamin.Rudiak-Gould at cl.cam.ac.uk
Wed Oct 27 05:50:24 EDT 2004
One idea that might not occur to a newcomer is to represent each set by
a function with a type like (Double -> Bool), implementing the set
membership operation. This makes set-theoretic operations easy: the
complement of s is not.s (though watch out for NaNs!), the union of s
and t is (\x -> s x || t x), and so on. Open, closed, and half-open
intervals are easy too. The big limitation of this representation is
that there's no way to inspect a set except by testing particular values
for membership, but depending on your application this may not be a problem.
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