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

1 May 2008

      2008/5/2 Galchin, Vasili :
...
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

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

Luke Palmer