[Haskell-cafe] elementary Maybe Monad problem .. sigh

[Brent Yorgey]

2008/5/1 Galchin, Vasili <vigalchin at gmail.com>:

> Sorry .. my example was bad.  I want to use "x" .. in  then  branch where
> it occur ...
>
> e.g.
>       bonzo :: Maybe Bozo -> IO ()
>       bonzo  maybe_bozo = do
>           case maybe_bozo of
>               Just (Bozo x) -> x ........
>               _                    -> .........
>
> ??
>

Sure, after pattern-matching on the x (using a case, or a top-level pattern
match), you are free to use x in the resulting branch.  For example:

bonzo (Just (Bozo x)) = print (show x) >> return x  -- or whatever
bonzo Nothing = return ()

-Brent
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