On Feb 6, 2008 1:49 PM, Lutz Donnerhacke <[EMAIL PROTECTED]> wrote:
>  inv m = if m == mzero then return () else mzero `asTypeOf` m

Interesting!

> :t inv
inv :: (MonadPlus m, Eq (m ())) => m () -> m ()

The 'Eq' constraint on 'm ()' is a bit problemetic I think in case 'm'
is a function like a 'State'.

Thanks,

Bas
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