[Haskell-cafe] matching constructors

[Koji Nakahara]

How about this approach ?
I think this is a conventional and clear way,
though Flag Verbose has a verbose String.

-----
import Data.List
import Data.Maybe

data Flag = Flag FlagType String
    deriving Show
getFlagType (Flag ft _) = ft

data FlagType = Verbose | Input | Output | Filter 
    deriving (Show, Eq)

findFlag f@(Flag ft _) xs = fromMaybe f (find ((ft ==).getFlagType) xs)

-- instance Eq Flag where
--   Flag ft1 _ == Flag ft2 _ = ft1 == ft2

----

--
Koji Nakahara