Re: container for different types, avoiding boiler plate

After taking a look at Data.Dynamic I came up with:

data Gender = Masc | Fem | Neutr deriving (Typeable, Show) data Number = First | Second | Third deriving (Typeable, Show)

type Attrs = [Dynamic]

attrs = [toDyn Masc, toDyn Second]

gattr :: (Typeable a) => Attrs -> Maybe a gattr [] = Nothing gattr (x:xs) = case fromDynamic x of Nothing -> gattr xs Just x -> Just x

type GetAttr a = Attrs -> Maybe a ggender = gattr :: GetAttr Gender gnumber = gattr :: GetAttr Number

which already is much more readable. But I'm sure problems are just around the corner ... Thank you. Markus