Hi Michael, Let me look tomorrow morning. In any case, many thanks!
Kind regards, Vasili On Tue, Jun 2, 2009 at 11:12 PM, Michael Snoyman <mich...@snoyman.com>wrote: > > remLookupFwd :: (ReVars m t) => SimplRe t -> ReM m t (ReInfo t) > > remLookupFwd re > > = do fwd <- gets resFwdMap > > -- let { Just reinfo = M.lookup fwd re } -- > PROBLEM > > reinfo <- liftMaybe $ M.lookup re fwd -- > PROBLEM > > return reinfo > > > > liftMaybe :: Monad m => Maybe a -> m a > > liftMaybe Nothing = fail "Nothing" > > liftMaybe (Just x) = return x > > I made two changes: > > 1. You had the arguments to M.lookup backwards. > 2. lookup does not return any generalized Monad, just Maybe (I think that > should be changed). I added the simple liftMaybe function to convert the > Maybe result into something that will work with your state monad. > > Michael >
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