[Haskell-cafe] Re: what does @ mean?.....
barsoap at web.de
Fri Dec 28 11:58:46 EST 2007
Achim Schneider <barsoap at web.de> wrote:
> zeroIf :: MonadPlus m => (a -> Bool) -> m a -> m a
> zeroIf f m = m >>= (\nz -> if f nz then mzero else m)
> zeroZero :: (MonadPlus m, Num a) => m a -> m a
> zeroZero = zeroIf (==0)
> makes it interesting again as you can't construct a Just value with
d'oh. return nz.
/me hides under a monad.
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