Here is a simpler case of what I want to do ..
1) To function1 pass in (Maybe Int).
2) If "Nothing" then pass nullPtr to C function.
3) If "Just 1", then pass a pointer to a "1" to teh same C function.
Thanks, Vasili
On Thu, May 1, 2008 at 8:18 PM, Galchin, Vasili <[EMAIL PROTECTED]> wrote:
> 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 <[EMAIL PROTECTED]> wrote:
>
> > 2008/5/2 Galchin, Vasili <[EMAIL PROTECTED]>:
> > >
> > > 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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