Well, yes; then, that means that "an arbitrary element" is also false: you can't just take an arbitrary element and hope that works well.
Then the original question must be reformulated: - Are there any functors for which there exists at least one non-bottom value of type 'f a' for some a, but there does not exist a function point :: a -> f a such that (a != _|_) => (point a != _|_). 2009/3/13 Brent Yorgey <byor...@seas.upenn.edu>: > On Fri, Mar 13, 2009 at 05:35:31PM +0300, Eugene Kirpichov wrote: >> 'An arbitrary element' means 'undefined will suffice' >> >> point x = fmap (const x) undefined > > This is false. > > Prelude> fmap (const 1) [()] > [1] > Prelude> fmap (const 1) undefined > *** Exception: Prelude.undefined > > -Brent > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > -- Eugene Kirpichov Web IR developer, market.yandex.ru _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe