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

[Galchin, Vasili]

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 ........
              _                    -> .........

??

Thanks, V.


On Thu, May 1, 2008 at 7:50 PM, Luke Palmer <lrpalmer at gmail.com> wrote:

> 2008/5/2 Galchin, Vasili <vigalchin at gmail.com>:
> >
> > data Bozo =
> >     Bozo {
> >       id :: Int
> >     }
> >
> > bonzo :: Maybe Bozo -> IO ()
> > bonzo   maybe_bozo = do
> >    if maybe_bozo == (Just (Bozo  x))
> >       then
> >          return ()
> >       else
> >          return ()
>
> bonzo maybe_bozo =
>    case maybe_bozo of
>        Just (Bozo x) -> return ()
>        _             -> return ()
>
> Or equivalently:
>
> bonzo (Just (Bozo x)) = return ()
> bonzo _               = return ()
>
> You should watch out for your use of id as a field name, since id is a
> builtin function and you will get ambiguity errors.
>
> Luke
>
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