12 Feb
2009
12 Feb
'09
1:24 p.m.
On Thu, 2009-02-12 at 19:04 +0100, Lennart Augustsson wrote:
They are not unsafe in the way unsafePerformIO is,
I beg permission to demur: newtype Unsafe alpha = Unsafe { unUnsafe :: alpha } instance Typeable (Unsafe alpha) where typeOf _ = typeOf () pseudoSafeCoerce :: alpha -> Maybe beta pseudoSafeCoerce = fmap unUnsafe . cast . Unsafe Note that pseudoSafeCoerce = Just . unsafeCoerce
but I regard them as a last resort in certain situations. Still, in those situations they are very useful.
But I would agree with both of these. As long as you *derive* Typeable. jcc